Method for dehydrating microbial cellulose

Abstract

The present invention relates to a method for dehydrating microbial cellulose, comprising a contact step of bringing a moist microbial cellulose material into contact with a hydrophilic polymer solution; a maintenance step of maintaining contact between the moist microbial cellulose material and the hydrophilic polymer solution for a processing time and removing at least a portion of the water from the moist microbial cellulose material; and a removal step of removing the dehydrated microbial cellulose from the hydrophilic polymer solution. The present invention further relates to a dehydrated microbial cellulose material comprising 25-95% microbial cellulose by dry weight and 5-75% hydrophilic polymer by dry weight.

Description

[Technical Field]

[0001] This invention relates to a method for dehydrating microbial cellulose. More specifically, the method of this invention produces dehydrated microbial cellulose with improved water absorption and water retention capabilities. This invention further relates to dehydrated microbial cellulose materials.

[0002] The present invention further relates to a method for producing a plant growth medium. More specifically, the present invention provides a method for producing a plant growth medium by dehydrating microbial cellulose. The present invention further relates to a plant growth medium. [Background technology]

[0003] The following background art description is intended solely to facilitate understanding of the present invention. This description does not constitute an endorsement that any of the materials referred to were or were part of the common technical knowledge as of the priority date of this application.

[0004] Microbial cellulose, also known as bacterial cellulose, is a natural cellulose synthesized by bacteria. Microbial cellulose is produced as thin fibrils, typically with a diameter of 20-100 nm. These thin fibrils intertwine to form a dense, three-dimensional matrix. Microbial cellulose is highly hydrophilic and has a high surface area-to-mass ratio, resulting in high water retention. The water content of moist microbial cellulose is approximately 99% in its original state. The resulting moist microbial cellulose forms a gelatinous pellicle.

[0005] Untreated microbial cellulose pellicle can be dried by evaporating water from within the fibrous matrix. However, it has been found that drying this material leads to irreversible internal hydrogen bonding. This process is also called "keratinization." While not theoretically bound, it is understood that water crosslinks microbial cellulose fibers with hydrogen bonds, maintaining fiber separation. Dehydration due to water loss by evaporation breaks these crosslinks, causing aggregation and stacking of microbial cellulose fibers. Keratinization of microbial cellulose dramatically reduces its water absorption and retention capacity. Depending on temperature and conditions, dried material cannot be rehydrated with more than 1 to 10 times its weight in water. To maintain the original water retention properties of microbial cellulose, untreated microbial cellulose needs to be kept moist, which complicates the storage and transportation of microbial cellulose materials.

[0006] One useful application of microbial cellulose is as a plant growth medium. This is primarily due to the material's high water absorption and retention capacity. However, since these capacities are lost when dried, it is necessary to maintain the microbial cellulose in a moist state to fully utilize these properties. This increases the cost of transporting and storing the product. Dried microbial cellulose can be rehydrated for use as a plant growth medium, but the drying process reduces the water absorption and retention capacity of the rehydrated material, affecting its performance as a plant growth medium.

[0007] Throughout this specification, unless otherwise specified by context, the word “comprise,” or variations such as “comprises” or “comprising,” is understood to mean that it includes the integer or group of integers described, but does not exclude any other integer or group of integers.

[0008] The inventions described herein may include a range of one or more values ​​(e.g., size, displacement, and electric field strength). A range of values ​​is understood to include all values ​​within the range, including the value that defines the range and the values ​​adjacent to the range that produce the same or substantially the same results as the values ​​immediately adjacent to the value that defines the boundary of the range. [Overview of the initiative]

[0009] According to a first aspect of the present invention, a method for dehydrating microbial cellulose, A contact process in which a moist microbial cellulose material is brought into contact with a hydrophilic polymer solution; A maintenance step to maintain contact between the moist microbial cellulose material and the hydrophilic polymer solution during the processing time and to remove at least a portion of the water from the moist microbial cellulose material; and Extraction process for dehydrated microbial cellulose from hydrophilic polymer solution A method including this is provided.

[0010] The inventors of this invention have confirmed that contact between moist microbial cellulose and a hydrophilic polymer solution removes at least some of the water from the moist microbial cellulose and replaces it with the hydrophilic polymer.

[0011] In one embodiment of the present invention, this method further, The process includes drying dehydrated microbial cellulose to produce dried microbial cellulose material.

[0012] The inventors of this invention have found that dried microbial cellulose material can be produced by removing the remaining water from dehydrated microbial cellulose using a conventional drying method. It was found that removing at least some of the water from the microbial cellulose using a hydrophilic polymer solution improves the water absorption and water retention capacity of the dried microbial cellulose. While not theoretically bound, it is understood that the inclusion of a hydrophilic polymer at least partially preserves the structure of the microbial cellulose throughout the subsequent drying process, thereby improving the water absorption and water retention capacity of the dried material.

[0013] In one embodiment of the present invention, the microbial cellulose material is produced by any suitable bacterial species known in the art, such as Sarcina sp., Agrobacterium sp., Komagataeibacter sp., and Acetobacter sp.

[0014] Throughout this specification, unless otherwise specified by context, the term “moist microbial cellulose” or its variation shall be understood to refer to a microbial cellulose material having a water content of at least 90% by weight. Preferably, the moist microbial cellulose has a water content of at least 95% by weight. More preferably, the moist microbial cellulose is not pre-dried.

[0015] Throughout this specification, unless otherwise specified in the context, the term “dehydrated microbial cellulose” or its variation shall be understood to refer to moist microbial cellulose material from which at least 50% by weight of the initial water content has been removed. Initial water content refers to the water content of the moist microbial cellulose before treatment.

[0016] In the method according to any of the preceding claims, the water content of the dehydrated microbial cellulose is 50% or less of the water content of the wet microbial cellulose.

[0017] In one embodiment of the present invention, the wet microbial cellulose is provided as a microbial cellulose pellicle or a segment thereof. Throughout this specification, unless otherwise required by context, the term "microbial cellulose pellicle" or variations thereof is understood to refer to a microbial cellulose material produced by static fermentation. Those skilled in the art will recognize that microbial cellulose by static fermentation is produced by bacteria as a three-dimensional matrix of microbial cellulose fibrils. This matrix is formed as a high-density pellicle having a gelatinous membrane-like form. The term "microbial cellulose pellicle" is understood to exclude microbial cellulose materials produced by agitated fermentation. Preferably, the microbial cellulose material is not subjected to homogenization or pulping treatment before being processed using the method of the present invention.

[0018] In one embodiment of the present invention, the wet microbial cellulose pellicle is cut into segments before being processed using the method of the present invention. Preferably, the wet microbial cellulose pellicle segments have a minimum size of 1 cm 3 .

[0019] In one embodiment of the present invention, the microbial cellulose content of the wet microbial cellulose material is less than 5% by weight. Preferably, the microbial cellulose content of the wet microbial cellulose material is 0.5 to 1.0% by weight.

[0020] Preferably, the hydrophilic polymer solution contains one or more polysaccharides. More preferably, the polysaccharide is selected from one or more of guar gum, acacia gum, ι-carrageenan, carboxymethyl cellulose (CMC), and alginate. Even more preferably, the hydrophilic polymer solution is a CMC solution. The carboxymethyl cellulose used is preferably an alkali metal salt of carboxymethyl cellulose. For example, the sodium salt, potassium salt, or ammonium salt of CMC. Unless otherwise specified, CMC referred to in this specification refers to the sodium salt of CMC.

[0021] Preferably, the concentration of the hydrophilic polymer solution is less than 20%. More preferably, the concentration of the hydrophilic polymer solution is less than 10%. In one embodiment of the present invention, the concentration of the hydrophilic polymer solution is 2 - 10%. In another embodiment of the present invention, the concentration of the hydrophilic polymer solution is 2 - 6%. In another embodiment of the present invention, the concentration of the hydrophilic polymer solution is 1 - 3%.

[0022] In one embodiment of the present invention, the ratio of the hydrophilic polymer solution to the wet microbial cellulose is at least 0.5:1. In one embodiment of the present invention, the ratio of the hydrophilic polymer solution to the wet microbial cellulose is at least 1:1. In one embodiment of the present invention, the ratio of the hydrophilic polymer solution to the wet microbial cellulose is at least 2:1.

[0023] Preferably, the wet microbial cellulose material is immersed in the hydrophilic polymer solution.

[0024] In one embodiment of the present invention, the treatment time is at least 6 hours. Preferably, the treatment time is at least 12 hours. More preferably, the treatment time is at least 24 hours. Even more preferably, the treatment time is at least 48 hours.

[0025] In one embodiment of the present invention, the contact between the wet microbial cellulose material and the hydrophilic polymer solution is carried out at ambient temperature.

[0026] In another embodiment of the present invention, the contact between the wet microbial cellulose material and the hydrophilic polymer solution is carried out at a high temperature. In one embodiment of the present invention, the temperature is 50 - 100°C. In another embodiment of the present invention, the temperature is 50 - 70°C. In one embodiment of the present invention, the high temperature is maintained during the treatment time. In another embodiment of the present invention, the high temperature is maintained for a part of the treatment time.

[0027] In one embodiment of the present invention, the weight of the dehydrated microbial cellulose is less than 40% of the weight of the wet microbial cellulose material. Preferably, the weight of the dehydrated microbial cellulose is 5 - 20% of the weight of the wet microbial cellulose material.

[0028] In one embodiment of the present invention, dehydrated microbial cellulose is further brought into contact with a hydrophilic polymer solution to remove additional water.

[0029] In one embodiment of the present invention, the drying of dehydrated microbial cellulose is carried out at ambient temperature. In another embodiment of the present invention, the drying of dehydrated microbial cellulose is carried out at high temperature.

[0030] In one embodiment of the present invention, dried microbial cellulose is subjected to a size reduction treatment.

[0031] According to a second aspect of the present invention, a dehydrated microbial cellulose material produced by the method of the first aspect of the present invention is provided.

[0032] According to a third aspect of the present invention, Microbial cellulose making up 25-95% by dry weight; and Hydrophilic polymers, 5-75% by dry weight A dehydrated microbial cellulose material is provided, which includes [the specified element].

[0033] Preferably, the hydrophilic polymer comprises one or more polysaccharides. More preferably, the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate. Even more preferably, the hydrophilic polymer is CMC.

[0034] Preferably, the hydrophilic polymer content is 5-60% by dry weight.

[0035] According to a fourth aspect of the present invention, a method for drying microbial cellulose, A contact process in which a moist microbial cellulose material is brought into contact with a hydrophilic polymer solution; A maintenance step to maintain contact between the moist microbial cellulose material and the hydrophilic polymer solution during the processing time and to remove at least a portion of the water from the moist microbial cellulose material; A extraction step for separating dehydrated microbial cellulose from a hydrophilic polymer solution; and Drying process to produce dried microbial cellulose material by drying dehydrated microbial cellulose A method including this is provided.

[0036] According to a fifth aspect of the present invention, a dried microbial cellulose material produced by the method of the fourth aspect of the present invention is provided.

[0037] According to a sixth aspect of the present invention, a method for producing a plant growth medium, A contact process in which a moist microbial cellulose material is brought into contact with a hydrophilic polymer solution; A maintenance step to maintain contact between the microbial cellulose material and the hydrophilic polymer solution during the processing time and to remove at least a portion of the water from the wet microbial cellulose material; and Extraction process to obtain a plant growth medium by extracting dehydrated microbial cellulose from a hydrophilic polymer solution. A method is provided that includes this.

[0038] Throughout this specification, unless otherwise specified by context, the term “plant growing medium” or its variation shall be understood to refer to a growing medium that can be used as a substitute for soil as a support for plant growth. Such a medium provides a substance on which seeds can germinate and provides a support for the plant's root system. It will be understood that the prepared plant growing medium requires the addition of water to enable plant growth.

[0039] Microbial cellulose is known to be useful as a plant growth medium due to its high water absorption and retention capacity. However, drying microbial cellulose using conventional evaporation drying techniques significantly reduces its water absorption and retention capacity. The dehydration method of the present invention has been found to produce dehydrated microbial cellulose material with improved water absorption and retention capacity. This improvement in water absorption and retention capacity increases the amount of water available to plants, making it beneficial for use as a plant growth medium.

[0040] In one embodiment of the present invention, this method further, Drying process to obtain a dry plant growth medium by drying dehydrated microbial cellulose. Includes.

[0041] The inventors have found that by removing at least a portion of the water from moist microbial cellulose using a hydrophilic polymer solution, the remaining water can be removed from dehydrated microbial cellulose using a conventional drying method, thereby producing a dried material with improved water absorption and retention capabilities.

[0042] In one embodiment of the present invention, the plant growth medium is subjected to a size reduction treatment. In one embodiment of the present invention, the dried plant growth medium is subjected to a size reduction treatment. Seed germination is possible on untreated moist microbial cellulose, but the inventors determined that after germination, the roots cannot penetrate the dense fibril network structure. Therefore, the roots cannot fully utilize the water retained within the microbial cellulose structure. The inventors discovered that by reducing the particle size of microbial cellulose, it is possible to allow plant root penetration while maintaining the water retention necessary for suitability as a plant growth medium. Advantageously, unlike the dense network structure of untreated microbial cellulose, the roots of plant seeds can penetrate the reduced-size material and obtain structural support for a properly developing root system. Furthermore, it was found that reducing the particle size also increases the water absorption rate. In one embodiment of the present invention, the particle size of the dried plant growth medium is reduced to D90, which is less than 1000 μm, by the size reduction treatment. In one embodiment of the present invention, the particle size of the dried plant growth medium is reduced to D50, which is less than 500 μm, by a size reduction treatment. In another embodiment of the present invention, the particle size of the dried plant growth medium is reduced to D10, which is greater than 50 μm, by a size reduction treatment.

[0043] Preferably, the size reduction process is a mechanical size reduction process.

[0044] In one embodiment of the present invention, the method further comprises bringing a plant growth medium into contact with water. Preferably, the mixture of the plant growth medium and water is stirred.

[0045] According to a seventh aspect of the present invention, a plant growth medium produced by the method of the fourth aspect of the present invention is provided.

[0046] According to the eighth aspect of the present invention, Microbial cellulose making up 25-75% by dry weight; and Hydrophilic polymers, 25-75% by dry weight A plant growth medium containing the following is provided.

[0047] Preferably, the hydrophilic polymer content is 30-60% by dry weight.

[0048] Preferably, the hydrophilic polymer is selected from one or more polysaccharides. More preferably, the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate. Even more preferably, the hydrophilic polymer is CMC. [Brief explanation of the drawing]

[0049] Further features of the present invention are described more fully in the following description of some non-limiting embodiments. This description is included solely for illustrative purposes of the invention and should not be understood as a limitation to the broad summary, disclosure, or description of the invention above. The following description is made with reference to the accompanying drawings. [Figure 1] Figure 1 is a graph showing the decrease in pellicle thickness during contact with a hydrophilic polymer solution. [Figure 2] Figure 2 is a graph showing the water retention capacity of dry materials with various particle sizes. [Modes for carrying out the invention]

[0050] This invention relates to a method for dehydrating microbial cellulose. The method of this invention includes contacting moist microbial cellulose with a hydrophilic polymer solution to reduce the water content of the moist microbial cellulose. Next, the dehydrated microbial cellulose is removed from the hydrophilic polymer solution. It has been found that the water absorption and water retention capacity of the dehydrated product is improved by the method of this invention compared to conventional drying methods. It has also been found that the energy required to remove water from the moist microbial cellulose material is reduced by the method of this invention. In certain embodiments, the dehydrated material can be subjected to a drying step to remove the remaining water and produce a dried microbial cellulose material.

[0051] Microbial cellulose The method of the present invention is intended to remove water from moist microbial cellulose. Throughout this specification, unless otherwise specified in the context, the term "microbial cellulose" means cellulose produced by bacteria.

[0052] Microbial cellulose for use in the method of the present invention can be produced by various means well known in the art.

[0053] In a preferred embodiment of the present invention, microbial cellulose is microbial cellulose produced by bacteria of the genus Acetobacter. Acetobacter bacteria can be readily identified by those skilled in the art by the growth of colonies on a medium containing about 7% ethanol and enough calcium carbonate to partially opaque the medium. As the Acetobacter colonies form sufficient acetic acid from the ethanol, the calcium carbonate around the colonies dissolves, forming a very distinct transparent zone.

[0054] In the static fermentation process, microbial cellulose forms as a sheet-like pellicle on the surface of the culture medium. As growth continues, the thickness of the untreated microbial cellulose pellicle increases. Once the desired thickness is reached, the moist microbial cellulose material is recovered. Recovery of the moist microbial cellulose material involves removing the microbial cellulose pellicle from the culture medium. In one embodiment, the thickness of the microbial cellulose is 0.5 to 5 cm. In one embodiment, the thickness of the microbial cellulose is 0.5 to 4 cm. In one embodiment, the thickness of the microbial cellulose is 0.5 to 3 cm. In one embodiment, the thickness of the microbial cellulose is 0.5 to 2 cm. In one embodiment, the thickness of the microbial cellulose is 0.5 to 1 cm.

[0055] In certain embodiments, the moist microbial cellulose is washed before contact with the hydrophilic polymer solution. Washing preferably involves heating the moist microbial cellulose in water at a temperature of 60°C to 100°C. The moist microbial cellulose may be washed several times.

[0056] In certain embodiments, the moist microbial cellulose is subjected to a purification step before contact with a hydrophilic polymer solution. The purification step preferably includes contacting the moist microbial cellulose with a detergent.

[0057] Moist microbial cellulose should not be dried before contact with hydrophilic polymer solutions.

[0058] Contact with hydrophilic polymer solution Moist microbial cellulose is brought into contact with a hydrophilic polymer solution, and this contact is maintained throughout the processing time. Contact between the microbial cellulose and the hydrophilic polymer solution removes some of the water from the moist microbial cellulose. While not theoretically bound, it is presumed that water is drawn out from within the moist microbial cellulose because the hydrophilic polymer has greater hydrophilicity than the microbial cellulose. Contact between the microbial cellulose and the hydrophilic polymer solution also allows the hydrophilic polymer to penetrate into the structure of the microbial cellulose. This reduces the degree of keratinization within the structure when residual water is removed, resulting in a dry material with excellent water absorption and retention capabilities.

[0059] Preferably, the moist microbial cellulose material is provided as a pellicle or its segments. It should be understood that the microbial cellulose pellicle treated according to the present invention may be divided into smaller segments before contact with the hydrophilic polymer solution. The structure of the microbial cellulose should otherwise remain unchanged. The moist microbial cellulose to be contacted with the hydrophilic polymer solution should not be subjected to prior homogenization or similar pulping treatments. As will be understood by those skilled in the art, homogenization of untreated microbial cellulose breaks down the dense network of fibrils, forming a pulp of crushed microbial cellulose. The inventors of the present invention have found that when such pulp is contacted with the hydrophilic polymer solution, the dehydrated microbial cellulose cannot be easily separated from the aqueous phase. Furthermore, the moist microbial cellulose to be contacted with the hydrophilic polymer solution should not be produced by a stirring fermentation treatment. Microbial cellulose produced by stirring fermentation has a pulp-like consistency and faces similar separation problems.

[0060] Preferably, the moist microbial cellulose is immersed in a hydrophilic polymer solution.

[0061] Preferably, the hydrophilic polymer solution contains one or more polysaccharides. More preferably, the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate. Even more preferably, the hydrophilic polymer solution is a CMC solution.

[0062] Preferably, the concentration of the hydrophilic polymer solution is less than 20%. More preferably, the concentration of the hydrophilic polymer solution is less than 10%.

[0063] The inventors have discovered that the maximum concentration of a hydrophilic polymer solution depends on its viscosity. If the viscosity is too high, the polymer solution becomes a thick gel, reducing its efficiency and making it difficult to handle. As will be understood by those skilled in the art, the viscosity of a hydrophilic polymer solution depends on the type of polymer, the concentration of the polymer, and the solution temperature. Polymers with a high average molecular weight exhibit higher viscosity in solution than polymers with a low molecular weight. Therefore, the maximum concentration of a hydrophilic polymer depends on the average molecular weight of the hydrophilic polymer solution.

[0064] As will be understood by those skilled in the art, polymer compositions contain polymer chains comprising repeating monomer units. The degree of polymerization (DP) is the number of monomer units in a polymer molecule. The molecular weight of a particular polymer molecule is the product of the degree of polymerization and the molecular weight of the repeating units. Polymer compositions consist of many polymer molecules having various chain lengths and molecular weights. This results in polymers having a molecular weight distribution. The average molecular weight of a polymer can be described by many parameters. For the purposes of this application, the average molecular weight of a polymer is defined as the weight-average molecular weight (M w The weight-average molecular weight of a polymer is clearly defined in the literature and can be determined by analytical methods such as gel permeation chromatography.

[0065] M of hydrophilic polymers w In embodiments where the value is less than 150,000, the concentration of the hydrophilic polymer solution is preferably 2 to 10%.

[0066] M of the hydrophilic polymer w In an embodiment where M is 150,000 to 500,000, the concentration of the hydrophilic polymer solution is preferably 2 to 6%.

[0067] M of the hydrophilic polymer solution w In an embodiment where M is greater than 500,000, the concentration of the hydrophilic polymer solution is preferably 1 to 3%.

[0068] The inventors have discovered that the average molecular weight of the hydrophilic polymer solution also affects the degree of water removal from wet microbial cellulose and the water absorption capacity of the resulting dry material. When the average molecular weight of the hydrophilic polymer solution is decreased, the amount of water removed from wet microbial cellulose decreases, but the polymer content of the resulting dry material increases. When the average molecular weight of the hydrophilic polymer is increased, the amount of water removed from wet microbial cellulose increases, but the polymer content in the resulting dry material decreases. Therefore, the hydrophilic polymer may be selected to prioritize increased water removal, improved swelling retention, or a combination thereof.

[0069] In one embodiment of the present invention, the hydrophilic polymer solution contains a mixture of a low average molecular weight (LM W ) hydrophilic polymer and a high average molecular weight (HM W ) hydrophilic polymer. The inventors have discovered that by including hydrophilic polymers having different average molecular weights, the overall water removal and polymer content of the dry product can be improved. Without being bound by theory, because the molecular size of the LM W hydrophilic polymer is small, it can penetrate more efficiently into the microbial cellulose matrix, and as a result, while its dehydration effect decreases, the opposite phenomenon occurs in the HM W hydrophilic polymer with a large molecular size.

[0070] In one embodiment, the hydrophilic polymer solution contains 1 to 2% of the HM W hydrophilic polymer and 0.5 to 4% of the LM WIt contains a hydrophilic polymer. In one embodiment, the hydrophilic polymer solution contains 1-2% HM W Hydrophilic polymer and 2-4% LM W Contains hydrophilic polymers.

[0071] In embodiments where the hydrophilic polymer solution contains two or more hydrophilic polymers with known average molecular weights, the overall average molecular weight of the hydrophilic polymers can be determined using the weighted average of each hydrophilic polymer. Similarly, the total concentration of the hydrophilic polymer solution is the total weight percent of each hydrophilic polymer.

[0072] In one embodiment, the ratio of the hydrophilic polymer solution to the moist microbial cellulose is at least 0.5:1. In another embodiment, the ratio of the hydrophilic polymer solution to the moist microbial cellulose is at least 1:1. In yet another embodiment, the ratio of the hydrophilic polymer solution to the moist microbial cellulose is at least 2:1. The hydrophilic polymer solution is diluted by removing water from the moist microbial cellulose into the hydrophilic polymer solution. As described above, in order to ensure sufficient water is removed from the moist microbial cellulose, the concentration of the hydrophilic polymer solution should be maintained above a certain concentration. The ratio of the hydrophilic polymer solution should be controlled so that the concentration of the hydrophilic polymer solution is not diluted below a minimum concentration. This ratio is influenced by the initial concentration of the hydrophilic polymer solution.

[0073] In one embodiment of the present invention, the processing time is at least 6 hours. In one embodiment, the processing time is at least 12 hours. In one embodiment, the processing time is at least 24 hours. In one embodiment, the processing time is at least 48 hours. Contact between the moist microbial cellulose and the hydrophilic polymer solution must be maintained for a sufficient time to reduce the water content of the microbial cellulose and for the hydrophilic polymer to diffuse into the microbial cellulose structure. The inventors understand that while water removal is a relatively rapid process, CMC penetration occurs relatively slowly. The inventors have found that the concentration of the hydrophilic polymer in the dehydrated material affects the water absorption and water retention capacity of the dried product. The processing time should be controlled to achieve the required hydrophilic polymer concentration. The thickness of the moist microbial cellulose material has been found to affect the required processing time. The inventors have found that for moist microbial cellulose material with a thickness of 0.5 to 1 cm, the optimal hydrophilic polymer concentration is achieved with a processing time of 24 to 72 hours. For thicker moist microbial cellulose material, an extended processing time of 72 to 96 hours may be required to achieve the optimal hydrophilic polymer concentration.

[0074] In one embodiment of the present invention, contact between the moist microbial cellulose material and the hydrophilic polymer solution is carried out at ambient temperature. In an alternative embodiment, the hydrophilic polymer solution is heated to over 50°C before contact. The heated hydrophilic polymer solution may be cooled before contact with the moist microbial cellulose material.

[0075] In alternative embodiments of the present invention, contact between the moist microbial cellulose material and the hydrophilic polymer solution is carried out at a high temperature. In one embodiment, the temperature is 50-100°C. In another embodiment, the temperature is 50-70°C. In one embodiment of the present invention, the high temperature is maintained throughout the processing time. In alternative embodiments of the present invention, the high temperature is maintained for part of the processing time. The inventors have found that contact between the moist microbial cellulose material and the hydrophilic polymer solution at a high temperature can increase the rate at which the hydrophilic polymer penetrates into the microbial cellulose material. This can shorten the required processing time.

[0076] A further advantage of contacting moist microbial cellulose material with a hydrophilic polymer solution at high temperatures is that it prevents the growth of bacteria and fungi.

[0077] dehydration products After the processing time is complete, remove the dehydrated microbial cellulose material from the hydrophilic polymer solution and remove any excess solution by lightly wiping or rubbing the surface. The remaining hydrophilic polymer solution can be used for further processing of the moistened microbial cellulose.

[0078] Removing water from microbial cellulose yields a much thinner material. In one embodiment of the present invention, the weight of the dehydrated microbial cellulose is less than 20% of the weight of the wet microbial cellulose material. Preferably, the weight of the dehydrated microbial cellulose is 5-20% of the weight of the wet microbial cellulose material. The weight of the dehydrated microbial cellulose can be used to determine whether sufficient water has been removed by the hydrophilic polymer solution. If sufficient water has not been removed, the dehydrated microbial cellulose can be brought into contact with the hydrophilic polymer solution again to remove further water.

[0079] Dehydrated microbial cellulose materials have a hydrophilic polymer content. The final hydrophilic polymer content is a result of the processing time, contact temperature, thickness of the moist microbial cellulose, concentration of the hydrophilic polymer solution, and type of hydrophilic polymer used. In one embodiment, the dehydrated microbial cellulose material has a hydrophilic polymer content of 5-75% by dry weight. The hydrophilic polymer content has been found to affect the water absorption and water retention capacity of the dehydrated microbial cellulose material. A hydrophilic polymer content of 30-60% by dry weight has been found to improve the water absorption capacity of the dehydrated material. However, even a low polymer content of 5% by dry weight, obtained by more efficient dehydration, can adequately absorb and retain the water required for a particular application while preventing keratinization. A hydrophilic polymer content exceeding 75% by dry weight is detrimental to water absorption and water retention capacity because there is insufficient microbial cellulose in the material during rehydration. The hydrophilic polymer content can be controlled to suit the desired purpose by selecting the polymer used and adjusting the processing time, contact temperature, thickness of the moist microbial cellulose, and concentration of the hydrophilic polymer solution.

[0080] The present invention provides a method for rapidly producing dehydrated microbial cellulose products that can be rehydrated. Removing water from wet microbial cellulose reduces the weight and thickness of the cellulose material, which is considered advantageous for the transport and storage of microbial cellulose materials. The dehydration method of the present invention allows for the removal of water for transport and storage without substantially affecting the rehydration of the dehydrated material. The dehydrated material is also considered useful for introducing additives such as antibiotics and vitamins into microbial cellulose. Such additives can be absorbed by the dehydrated microbial cellulose during rehydration. Dehydrated microbial cellulose is also expected to allow for the use of unstable additives that would otherwise degrade during transport and storage, at the time of use.

[0081] In the dehydration method of the present invention, since all water is not completely removed from the moist microbial cellulose, the resulting dehydrated microbial cellulose is a hydrated material. This dehydrated microbial cellulose material is suitable for applications where a hydrated material is preferred. Such applications are expected to include cosmetic applications such as skincare, and healthcare applications such as wound healing. Furthermore, this hydrated material is also suitable for applications where a flexible material is useful.

[0082] dry In one embodiment of the present invention, dehydrated microbial cellulose is subjected to a drying process to remove residual water from the material. The inventors have found that at least a substantial portion of the residual water in the dehydrated microbial cellulose can be removed to produce a dried material. Advantageously, this dried material has been found to exhibit improved water absorption and retention capabilities compared to dried microbial cellulose produced using conventional drying techniques alone. Removing the remaining water from the dehydrated microbial cellulose material further reduces the weight and thickness of the microbial cellulose, thereby reducing shipping / transportation costs. Furthermore, the method of the present invention eliminates the need to store wet microbial cellulose in a controlled environment to prevent unintended drying. The high water absorption and retention capabilities of the dried material also make it possible to use it as a biodegradable absorbent material.

[0083] Preferably, evaporative drying is used to dry the dehydrated microbial cellulose material. Throughout this specification, the term “evaporative drying” is understood to include any process that evaporates water from within the dehydrated, moist microbial cellulose material. Suitable evaporative drying processes include air drying, convection drying, contact drying, radiation drying including infrared radiation, dielectric drying including microwaves, high-frequency drying, freeze-drying, and vacuum drying. In one embodiment, drying of the dehydrated microbial cellulose is carried out at ambient temperature. In an alternative embodiment, drying of the dehydrated microbial cellulose is carried out at a high temperature. Preferably, drying is carried out at a temperature of at least 70°C.

[0084] Size reduction The dehydrated material may retain its original shape. Alternatively, the dehydrated material may be subjected to a size reduction treatment. The inventors have discovered that the particle size of the dehydrated material can be freely reduced without significantly affecting its water absorption capacity. In embodiments of this method that include a drying step, the dried material may retain its original shape. Alternatively, the dried material may be subjected to a size reduction treatment. The inventors have discovered that the particle size of the dried material can be freely reduced without significantly affecting its water absorption capacity.

[0085] product The present invention further relates to a dehydrated microbial cellulose product produced using the above-described dehydration treatment.

[0086] In one embodiment, the dehydrated microbial cellulose material is Microbial cellulose making up 25-95% by dry weight; and Hydrophilic polymers, 5-75% by dry weight Includes.

[0087] Preferably, the hydrophilic polymer concentration is 5-60% by dry weight.

[0088] The present invention further relates to a dried microbial cellulose product produced using the above-described drying process.

[0089] In one embodiment, the dried microbial cellulose material is 25-95% microbial cellulose; and 5-75% hydrophilic polymer Includes.

[0090] Preferably, the hydrophilic polymer concentration is 5-60%.

[0091] growing material The present invention further relates to a method for producing a plant growth medium, Contacting a moist microbial cellulose material with a hydrophilic polymer solution; Maintaining contact between the microbial cellulose material and the hydrophilic polymer solution during the processing time; and Dehydrated microbial cellulose is extracted from the solution to obtain a plant growth medium. Regarding methods including

[0092] Microbial cellulose is known to be useful as a plant growth medium due to its high water absorption and retention capacity. However, when microbial cellulose is dried using conventional evaporation drying techniques, its water absorption and retention capacity is significantly reduced. The dehydration method of the present invention has been found to produce dehydrated microbial cellulose material with improved water absorption and retention capacity. This improvement in water absorption and retention capacity is beneficial for the use of the material as a plant growth medium because it increases the amount of water available to plants.

[0093] The plant growth medium of the present invention is intended to be reconstituted with water to make it suitable for plant growth. Advantageously, the inventors have confirmed that the applicability of the method of the present invention allows for the cost-effective dehydration of dehydrated microbial cellulose and its transport from the place of production to the place where it is to be used as a plant growth medium.

[0094] The discussion of the method for dehydrating microbial cellulose according to the first aspect of the present invention is also applicable to dehydration treatments used for producing plant growth media.

[0095] Preferably, the hydrophilic polymer solution contains one or more polysaccharides. More preferably, the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate. Even more preferably, the hydrophilic polymer solution is a CMC solution.

[0096] In one embodiment, this method further A process for producing a dried plant growth medium by drying dehydrated microbial cellulose. Includes.

[0097] In a preferred embodiment, the dried plant growth medium is subjected to a size reduction treatment. The inventors have found that reducing the particle size helps plant roots penetrate the plant growth medium. Furthermore, it has been found that reducing the particle size also improves the water absorption rate.

[0098] In one embodiment, the particle size of the dried plant growth medium is reduced to D90, which is less than 1000 μm, by a size reduction process.

[0099] In one embodiment, the particle size of the dried plant growth medium is reduced to a D50 of less than 500 μm by the size reduction process. Preferably, the particle size of the dried plant growth medium is reduced to a D50 of less than 400 μm by the size reduction process.

[0100] In one embodiment, the particle size of the dried plant growth medium is reduced to D10, which is larger than 50 μm, by a size reduction process.

[0101] As those skilled in the art will understand, particle size distribution is often expressed using D values. The meaning of each D value is as follows: D10: A size where 10% of the particles by volume are smaller than the size of the particles; D50: A size in which 50% of the particles by volume are smaller; and D90: A size where 90% of the particles are smaller by volume.

[0102] For the purposes of this invention, the term "particle size" is defined as the size of a particle determined by sieve size analysis based on sieve testing, which is described in more detail herein. A sample of particles is sieved as described, and the results are recorded. The results of such sieve size analysis adequately define the particle size for the purposes of this invention. The results of sieve analysis can be expressed by two equivalent conventions with respect to the characteristics of the sieve used. One way of expressing particle size is with respect to the size of the sieve opening. For example, as a rule, particles held on a sieve with a 500 μm opening are considered to have a particle size of 500 μm or larger for the purposes of this invention. Particles that pass through a sieve with a 500 μm opening and are held on a sieve with a 100 μm opening are considered to have a particle size of 100 to 500 μm.

[0103] As those skilled in the art will understand, for non-spherical particles, sieving tests may only measure the size of specific particles of a particular dimension. In the case of elongated particles, the shorter dimension of the particle may pass through the mesh opening, and as a result, particles with a larger cross-sectional area may pass through the mesh. For this reason, the test results are generally expressed as the volume percentage of particles that normally pass through a sieve of one size and are retained on a sieve of another size.

[0104] Preferably, the size reduction process is a mechanical size reduction process. As those skilled in the art will understand, a mechanical size reduction process involves breaking the material under stress applied by a mechanical force. The mechanical force may be selected from one or more of tensile stress, bending stress, compressive stress, torsional stress, impact stress, and shear stress. Preferably, the mechanical force is one or more of compressive stress, impact stress, and shear stress.

[0105] The inventors have found that mechanical size reduction using high-speed rotating blades is particularly useful. In such a process, it is understood that the mechanical forces consist mainly of impact forces resulting from collisions between the rotating blades and the microbial cellulose, and shear forces resulting from velocity differences within the medium. As those skilled in the art will understand, any apparatus capable of applying mechanical forces to microbial cellulose is suitable. Preferably, the apparatus is a blender.

[0106] In one embodiment of the present invention, the method further includes bringing a plant growth medium into contact with water. Preferably, the mixture of the plant growth medium and water is stirred.

[0107] Example 1 Molecular weight of hydrophilic polymers (M w A series of tests were conducted to investigate the effects of CMC and hydrophilic polymer concentrations on the dehydration of moist microbial cellulose. Fourteen CMC solutions were prepared using low molecular weight CMC (90,000), medium molecular weight CMC (250,000), and high molecular weight CMC (700,000). The CMC concentrations in the solutions ranged from 0.5% to 10%, depending on the molecular weight of the CMC solution. In each test, approximately 70-80 g of untreated moist microbial cellulose pellicle pieces (unblended) were weighed and immersed in beakers containing 500 g of each CMC solution. The pellicles were kept in the CMC solution and left at room temperature. After 24 hours, the pellicles were removed from the solution and excess CMC solution was scraped off. The resulting material was then dried. The results are shown in Table 1. [Table 1]

[0108] Untreated moist microbial cellulose samples were treated with 500g of water, dried, and weighed to calculate the CMC content, thereby determining the ratio of dry MC weight to wet pellicle weight. Next, using this ratio, the dry weight of the pellicle without CMC was calculated, and this was subtracted from the dry weight to obtain the estimated CMC ratio.

[0109] Dehydration was measured by weighing the wet pellicle before treatment, removing excess CMC solution after 24 hours, and then calculating the percentage of water actually removed, taking into account the weight of the present microbial cellulose and CMC.

[0110] Swelling measurements were performed by immersing approximately 1 g of dry material in 500 ml of water for 72 hours (confirming a constant weight to ensure saturation and removal of CMC from microbial cellulose). The swelling rate was then calculated by dividing the wet weight of the obtained microbial cellulose by the weight of microbial cellulose in the dry material (i.e., the total dry weight minus the weight of CMC in the material).

[0111] Table 1 shows the molecular weight (M w This shows the differences between different CMCs. Low molecular weight CMCs have the lowest dehydration effect but the highest CMC absorption / content in the resulting material. High molecular weight CMCs have the highest dehydration effect but the lowest CMC absorption / content in the resulting material. Medium molecular weight CMCs show a dehydration effect similar to high molecular weight CMCs, but their CMC uptake is high (lower than low molecular weight CMCs). Therefore, the type of CMC can be selected for drying only, swelling retention only, or both swelling retention and drying.

[0112] Example 2 Molecular weight (M w A series of tests were conducted to investigate the effect of different hydrophilic polymer combinations on the dehydration of moist microbial cellulose. Five CMC solutions were prepared by combining various amounts of low and high molecular weight CMCs. In each test, approximately 70–80 g of untreated moist microbial cellulose pellicle (unblended) was weighed and immersed in a beaker containing 500 g of each CMC solution. The pellicle was kept in the CMC solution and left at room temperature. After 24 hours, the pellicle was removed from the solution and excess CMC solution was scraped off. The resulting material was then dried. The results are shown in Table 2. [Table 2]

[0113] Table 2 shows that using a mixture of multiple CMCs may be beneficial for achieving both dehydration and high swelling retention. It is theorized that high molecular weight CMCs contribute to the dehydration effect, while low molecular weight CMCs provide better CMC absorption / swelling retention. These results suggest that other mixtures of hydrophilic polymers with different molecular weights may also be beneficial.

[0114] Example 3 A series of tests were conducted to clarify the effect of the thickness of moist microbial cellulose on the rate of water removal by a high molecular weight CMC solution. Samples of moist microbial cellulose with different initial thicknesses were treated in a 3% CMC solution. Each sample was a circle with a diameter of 10 cm. Figure 1 shows the change in sample thickness over time.

[0115] These results indicate that most of the water is removed after 24 hours, and that a drying time of 48–72 hours is sufficient to remove most of the water. Note that doubling the thickness does not double the drying time.

[0116] Example 4 A series of tests were conducted to clarify the effect of temperature during contact between moist microbial cellulose and a high molecular weight CMC solution on the microbial cellulose after dehydration and drying. The test results are shown in Table 3. [Table 3]

[0117] Oven treatment significantly accelerates the rate at which CMC is incorporated into microbial cellulose. This is presumably partly due to the decrease in viscosity associated with the rise in temperature. Untreated material shows significant swelling loss without a CMC drying process.

[0118] Example 5 A series of experiments were conducted to clarify the effect of CMC concentration in dried microbial cellulose (MC) on seed germination. 0.5 g each of dried microbial cellulose, dried CMC-treated microbial cellulose, and CMC (high molecular weight) samples were treated with 50 ml of water. The samples were placed in seed germination trays (with drainage holes at the bottom) and treated with approximately 50 Brassica juncea seeds, and observed for one week. The results are shown in Table 4. [Table 4]

[0119] Example 6 A series of tests were conducted to clarify the effect of the particle size of dried microbial cellulose on the water retention capacity of the material after rehydration. Dried samples were prepared by contacting moist microbial cellulose with a CMC solution containing 2.3% high molecular weight CMC and 3% low molecular weight CMC for 24 hours. The dehydrated material was removed from the solution and dried at 70°C. The dried material was blended in a NutriBullet Rx blender for 3 minutes. The resulting powder was sieved (according to AS 1289.3.6.1) and fractions of 106 μm, 212 μm, 355 μm, 425 μm, and 500 μm were collected. Coir samples were also included for comparison.

[0120] 0.5 g of dried material from each particle size range was added to 50 ml of water and shaken for 2 minutes until a gel formed and the water was completely absorbed. Coir samples were also included for comparison. The resulting mixture was placed in a weighed tray with drainage holes and drained at room temperature and atmospheric pressure. The mixture was weighed at various intervals to obtain the water retention rate over time. The results are shown in Figure 2.

[0121] The results show that water retention is significantly affected by particle size. Smaller particle sizes result in higher water retention than larger particle sizes. It should also be noted that when using the same weight of coir (0.5g) as the treated microbial cellulose, its water content is completely lost within 24 hours, while the treated microbial cellulose retains more than 25% of its water even after 120 hours.

[0122] Example 7 The dried microbial cellulose of the present invention was compared with other commercially available plant growth media containing coir fibers. The microbial cellulose was treated with a 3% solution of high molecular weight CMC at 70°C for 96 hours, and then dried at 70°C. The pellets were then reduced in size and passed through a 1 mm sieve. Each coir pellet weighed 3.9–4.1 g (average 4 g) when dry, and measured 3 cm in diameter × 1.2 cm in thickness (8.5 cm per pellet). 3 The pellets were unpacked, crushed, and allowed to swell freely. In the test, after rehydration, the pellets were 6 × 6 × 2 cm (L × W × H) or 72 cm. 3 The dry volume of each material required to fill the seed germination tray compartment was measured. The results are shown in Table 5. [Table 5]

[0123] The results demonstrated that dried microbial cellulose required significantly less volume (87% less volume) and weight (90% less weight) to obtain a wet volume equivalent to that of coir material.

[0124] Comparative Example Conventional techniques have used CMC (Cellular Cellulose Mixture) as a means to prevent keratinization during drying of microbial cellulose pulp. Such pulp contains moist microbial cellulose that has been subjected to a grinding process. Tests were conducted to identify the conditions under which contact between microbial cellulose (MC) pulp and a CMC solution results in the removal of water from the pulp. 2% MC pulp was mixed with a 2% high molecular weight CMC solution in a 1:1 ratio and left overnight at room temperature. The mixture of CMC and MC formed a homogeneous gel, and no signs of dehydration were observed. Furthermore, it should be noted that treating MC pulp with a CMC solution produces a material that is more difficult to dehydrate than untreated pulp. This was evident in trials where both CMC-treated and untreated MC pulp were centrifuged through a fine mesh, in which case water was released more easily from the untreated pulp.

[0125] Those skilled in the art will understand that the inventions described herein are readily subject to modifications and alterations beyond those specifically described. The present invention includes all such modifications and alterations. The present invention also includes all of the processes, features, formulations and compounds mentioned or indicated herein, individually or collectively, and any and all combinations or any two or more of the processes or features.

Claims

1. A contact step in which a moist microbial cellulose material is brought into contact with a hydrophilic polymer solution; A maintenance step, which involves maintaining contact between the moist microbial cellulose material and the hydrophilic polymer solution during the processing time and removing at least a portion of the water from the moist microbial cellulose material; and Extraction process for dehydrated microbial cellulose from hydrophilic polymer solution A method for dehydrating microbial cellulose, including [specific components].

2. The method according to claim 1, wherein the moist microbial cellulose is provided as a microbial cellulose pellicle or a segment thereof.

3. The method according to claim 1, wherein the microbial cellulose content of the wet microbial cellulose material is less than 5% by weight.

4. The method according to claim 1, wherein the hydrophilic polymer solution contains one or more polysaccharides.

5. The method according to claim 4, wherein the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate.

6. The method according to claim 1, wherein the hydrophilic polymer solution is a CMC solution.

7. The method according to claim 1, wherein the concentration of the hydrophilic polymer solution is less than 20%.

8. The method according to claim 1, wherein the ratio of the hydrophilic polymer solution to the moist microbial cellulose is at least 0.5:

1.

9. The method according to claim 1, wherein the processing time is at least 6 hours.

10. The method according to claim 1, wherein the contact between the moist microbial cellulose material and the hydrophilic polymer solution is carried out at a high temperature.

11. The method according to claim 1, wherein the weight of the dehydrated microbial cellulose is less than 40% of the weight of the wet microbial cellulose material.

12. The method according to claim 1, further comprising a drying step of drying the dehydrated microbial cellulose to produce a dried microbial cellulose material.

13. Microbial cellulose making up 25-95% by dry weight; and Hydrophilic polymers, 5-75% by dry weight Dehydrated microbial cellulose material containing [the above].

14. The dehydrated microbial cellulose material according to claim 13, wherein the hydrophilic polymer contains one or more polysaccharides.

15. The dehydrated microbial cellulose material according to claim 14, wherein the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate.

16. The dehydrated microbial cellulose material according to claim 13, wherein the hydrophilic polymer is CMC.

17. The dehydrated microbial cellulose material according to claim 13, wherein the content of the hydrophilic polymer is 5 to 60% by dry weight.

18. A method for producing a plant growth medium, comprising the step of subjecting the aforementioned moist microbial cellulose material to the method according to any one of claims 1 to 11 to obtain a plant growth medium.

19. The dehydrated microbial cellulose is dried to obtain a dried plant growth medium; drying process The method according to claim 18, further comprising:

20. The method according to claim 19, wherein the dried plant growth medium is subjected to a size reduction treatment.

21. The method according to claim 20, wherein the particle size of the dried plant growth medium is reduced to a D90 of less than 1000 μm by the size reduction process.

22. Microbial cellulose making up 25-75% by dry weight; and Hydrophilic polymers, 25-75% by dry weight A plant growth medium containing [the specified ingredient].

23. The plant growth medium according to claim 22, wherein the hydrophilic polymer comprises one or more polysaccharides.

24. The plant growth medium according to claim 23, wherein the polysaccharide is selected from one or more of guar gum, acacia gum, iotacarrageenan, carboxymethylcellulose (CMC), and alginate.

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