Method for producing grease by directly utilizing starch-rich plant source traditional Chinese medicine residues

Abstract

The invention is applicable to the technical field of biorefinery of oleaginous yeast, and provides a method for producing grease by efficiently utilizing starch-rich plant-derived traditional Chinese medicine residues, which comprises the following steps: sterilizing selected plant-derived wet traditional Chinese medicine residues, preparing into a culture medium taking the traditional Chinese medicine residues as a unique component, and inoculating lipomyces starkeyi for fermentation without or with an extremely small amount of cellulase; in the fermentation process, amylase produced by yeast and additional cellulase jointly act on the traditional Chinese medicine residues, and the traditional Chinese medicine residues are rapidly degraded into fermentable sugar which is efficiently used for rapid production of grease. According to the method, the traditional Chinese medicine residues do not need to be subjected to any pretreatment, amylase production, enzyme hydrolysis and fermentation are highly integrated, the number of equipment is greatly reduced, the technological process is simplified, the production cost of the microbial oil is remarkably reduced, and a novel low-cost method is provided for solving the problems of treatment and recycling of large-block traditional Chinese medicine residues. The fatty acid composition of the produced microbial oil is similar to that of vegetable oil, and the microbial oil can be used as a substitute raw material of biodiesel.

Description

Technical Field

[0001] The invention belongs to the technical field of starch biomass biorefining, and in particular relates to a method for directly utilizing starch-rich plant-source Chinese medicine residues to produce oil. Background Art

[0003] There are some oil-producing microorganisms in nature. Under certain conditions, they can use various cheap carbohydrates as carbon sources to synthesize and store a large amount of oil in their bodies. Yeast that can accumulate oil in their cells and exceed 20% of the cell dry weight (w / w, where w / w means mass ratio, the same below) is called oil-producing yeast. The oil accumulated in some oil-producing yeast cells even exceeds 70% of their cell dry weight. The oil produced by oil-producing yeast is mainly composed of triglycerides, and the fatty acid composition is similar to that of animal and plant oils, with C 16 -C 18 Mainly long-chain fatty acids. Compared with animal and plant oils, microbial oils have the following characteristics: first, the production cycle is short, the land occupation is small, and it is not affected by seasonal climate change; second, it can use agricultural, forestry and domestic waste, and will not compete with people for food; third, the production stability is good, and the oil quality is easy to control, which is a new generation of oil resources with great potential. Microbial oils are also very versatile. They can not only be used as a substitute for cocoa butter, provide polyunsaturated fatty acids, and be used for medicinal adjuvants and dietary supplements, but also as an alternative lipid raw material for biodiesel production.

[0004] In recent years, Chinese herbal medicines have gained significant popularity not only in Asian countries but also around the world. As a result, the annual production of Chinese herbal medicine residues has increased exponentially, reaching more than 35 million tons in China alone. These residues are rich in cellulose, starch, lignin, and other substances, and are mainly solid residues left after the decoction of Chinese herbal medicines. They have a high water content and are prone to rot. Traditional disposal methods, such as landfill, incineration, and stacking, not only cause environmental pollution but also lead to waste of resources. To address this problem, researchers have explored various resource utilization methods. Among them, the bioconversion of Chinese herbal medicine residues to produce value-added bioproducts, such as microbial oils, ethanol, and lactic acid, has attracted great attention in recent years and has been widely studied.

[0005] Traditional Chinese medicine residues contain a large amount of carbohydrates such as cellulose, hemicellulose, starch, etc., as well as nitrogen substances such as proteins and amino acids, and various inorganic salts such as nitrogen, phosphorus, potassium, etc. required for microbial growth. They are rich in nutrients and meet almost all the needs of microbial growth. They can be said to be natural culture media. However, due to the presence of lignocellulose, a natural resistance component, the utilization of traditional Chinese medicine residues often needs to start with pretreatment. Common pretreatment methods include acid pretreatment, alkali pretreatment, etc. Because traditional Chinese medicine residues have been repeatedly boiled before formation, they are easier to degrade than the lignocellulose contained in stubborn corn stalks, wheat stalks, etc. Usually, the pretreated traditional Chinese medicine residues need to be hydrolyzed by enzymes to release most of the sugars contained therein. Such a process not only has complicated process flow, large number of equipment, and large floor space, but also the pretreatment process is often accompanied by a large amount of energy consumption. Coupled with the high enzyme cost, the utilization of traditional Chinese medicine residues is seriously hindered.

[0006] Starch-rich Chinese medicine residue refers to Chinese medicine residue that contains a large amount of starch, with a starch content of about 40-80%. In addition, it also contains cellulose, polysaccharides, proteins, amino acids, crude fat, nitrogen, phosphorus and other nutrients, which are sufficient to meet the growth needs of microorganisms. The structure of starch-rich Chinese medicine residue, especially the starch part, has been destroyed and gelatinized during repeated decoction, which is conducive to the direct use of starch-rich Chinese medicine residue with complex structural components by microorganisms.

[0007] Staryi lipogenic yeast is an oil-producing yeast that is often used in scientific research. It can not only quickly accumulate a large amount of microbial oil, but also directly utilize starch by producing amylase. The amylase produced by Staryi lipogenic yeast has strong activity and can quickly degrade starch in the early stage of fermentation to produce a large amount of fermentable sugar, greatly improving the efficiency of oil production.

[0008] There are two ways for oil-producing yeast to produce microbial oils from biomass: step hydrolysis and fermentation (SHF), which is characterized by the production of enzymes, enzymatic hydrolysis of biomass, and fermentation separately; there is also synchronous saccharification and fermentation (SSF), which is characterized by the simultaneous enzymatic hydrolysis and fermentation of biomass; and there is also integrated bioprocessing (CBP), which is characterized by the simultaneous production of enzymes, enzymatic hydrolysis of biomass, and fermentation. The most common way to utilize Chinese medicine residues to produce oils is SHF, but its process flow is complicated, the production cost is high, and the production cycle is long. These shortcomings seriously hinder the resource utilization of Chinese medicine residues. Therefore, it is necessary to adopt a highly integrated process to integrate the production of enzymes, enzymatic hydrolysis of biomass, and fermentation, which will significantly reduce the production cost and production cycle.

[0009] In order to utilize lignocellulose resources more efficiently, it is necessary to find a simpler and more economical method to simplify the process flow through simultaneous saccharification and fermentation, significantly increase oil production and oil yield, and improve the technical and economic efficiency of microbial oils. Summary of the invention

[0010] In view of the above problems, the purpose of the present invention is to provide a method for producing oil by directly utilizing starch-rich plant-based Chinese medicine residues, aiming to solve the current problems of difficulty in treating Chinese medicine residues, environmental pollution, and complex and high-cost processes for producing oil from Chinese medicine residues.

[0011] The method for producing oil by directly utilizing starch-rich plant-based Chinese medicine residues comprises the following steps:

[0012] Step S1: selecting Chinese medicinal residue raw materials, selecting plant-based wet Chinese medicinal residues with relatively high starch content;

[0013] Step S2: adding wet Chinese medicinal residues without any pretreatment after decoction into the reactor, adding an appropriate amount of deionized water, adjusting to a suitable solid-liquid ratio, adjusting the pH, and then performing a sterilization operation to obtain a Chinese medicinal residue culture medium;

[0014] Step S3: culturing the star yeast in a seed culture medium to obtain an oil-producing microbial seed liquid;

[0015] Step S4: inoculating the oil-producing microbial seed liquid obtained in step S3 into the traditional Chinese medicine residue culture medium obtained in step S2, adding no or a small amount of cellulase, and aerobically fermenting at an appropriate temperature for a period of time. When the traditional Chinese medicine residue solids in the culture medium are degraded and the reducing sugar concentration in the fermentation liquid is lower than 5g / L, the fermentation is terminated.

[0016] Step S5: separating the fermentation liquid into solid and liquid, collecting the solid phase where the oil-producing yeast is located, and then extracting microbial oil from the collected solid phase.

[0017] Specifically, in step S1, the Chinese medicine residue refers to starch-rich plant-source Chinese medicine residue, which contains various nutrients such as starch, cellulose, polysaccharides, protein, amino acids, crude fat, nitrogen, phosphorus, etc., wherein the starch content is 40%-80%, such as Chinese medicine residue containing components such as isatis root, white peony root, kudzu root, ginkgo, turmeric, peony bark, Poria, and astragalus, and their mixtures.

[0018] Specifically, in step S2, the Chinese medicinal residue without any pretreatment is directly added to the reactor, which is a large block of wet Chinese medicinal residue containing a large amount of water without any treatment after decoction. The solid-liquid ratio is adjusted so that the concentration of dry matter is in the range of 50-200 g / L and the pH range in the reactor is 5-6.5.

[0019] Specifically, in step S4, the volume of the oil-producing microbial seed liquid accounts for 2%-20% of the volume of the starch-rich plant-derived Chinese medicinal residue culture medium, the added amount of the cellulase is 0-1 FPU / g of Chinese medicinal residue, and the culture temperature is controlled at 25°C-35°C.

[0020] Specifically, in step S5, the oil obtained by extraction is an oil containing one or more long-chain fatty acids and their derivatives, which is suitable as an alternative raw material for biodiesel.

[0021] The beneficial effects of the present invention are:

[0022] 1. In the present invention, by directly utilizing the starch-rich plant-source Chinese medicine residues to produce oil, highly integrated processing of Chinese medicine residues (high integration of amylase production, enzyme hydrolysis of starch to prepare fermentable sugars, and oil fermentation by oleaginous yeast) is achieved. Compared with the conventional Chinese medicine residue resource utilization method (Chinese medicine residue crushing treatment, acid-base high-temperature pretreatment, enzyme hydrolysis, fermentation), the process flow is significantly reduced, and the equipment cost and time cost are reduced;

[0023] 2. In the present invention, by directly utilizing the starch-rich plant-source Chinese medicine residues to produce oil, the wet medicine residues that have not been processed after decoction are directly utilized. Compared with the conventional method that requires crushing and high-temperature acid-base pretreatment, the present invention greatly reduces energy consumption and environmental pollution, and has a strong application prospect;

[0024] 3. The Starch yeast used in the present invention can directly utilize starch without the need to add amylase and saccharifying enzyme. In the early stage of fermentation, the Starch yeast produces amylase that can quickly hydrolyze starch, produce more fermentable sugars for the use of oil-producing yeast, and improve the oil fermentation efficiency in the early stage of fermentation. At the same time, by adding a small amount of cellulase, the cellulose part in the traditional Chinese medicine residue that is not conducive to amylase hydrolysis can be removed, thereby expanding the utilization of the Starch yeast for the starch-rich plant-source traditional Chinese medicine residue and accelerating the accumulation efficiency of oil;

[0025] 4. In the present invention, by directly utilizing the starch-rich plant-source Chinese medicine residues to produce oil, there is no need to add amylase, and no or only a very small amount of cellulase is needed to efficiently degrade the Chinese medicine residues. Compared with the conventional Chinese medicine residue resource utilization method, the present invention greatly reduces the enzyme cost.

[0026] 5. In the present invention, the selected raw material Chinese medicine residue has rich nutrients, including starch, cellulose, polysaccharides, proteins, amino acids, crude fat, nitrogen, phosphorus, etc., which can meet all the requirements of the growth of oil-producing yeast. Therefore, a large amount of oil can be efficiently accumulated without adding any other nutrients, which not only reduces the cost of raw materials, but also simplifies the process operation, making the production easy to implement;

[0027] The method adopted by the present invention is simple and efficient, and significantly reduces the process flow, reduces the production cost, improves the production efficiency, oil output and oil yield of oil, and improves the technical and economic feasibility of producing microbial oil using traditional Chinese medicine residues. It has good application prospects. The oil obtained by the present invention is an oil of one or more long-chain fatty acids and their derivatives, which can be used for preparing biodiesel, as a cocoa butter substitute, medicinal diet, lubricating oil and other purposes, and has a broad application market. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of the method provided by the present invention for directly utilizing starch-rich plant-source Chinese medicine residues to produce oil through integrated bioprocessing. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] The present invention provides a method for producing oil by directly utilizing starch-rich plant-based Chinese medicine residues, which specifically comprises the following steps:

[0031] Step S1: Selection of Chinese medicinal residue raw materials, selecting plant-based wet Chinese medicinal residue with relatively high starch content.

[0032] In this step, the Chinese medicine residue refers to starch-rich plant-source Chinese medicine residue, which contains starch, cellulose, polysaccharides, protein, amino acids, crude fat, nitrogen, phosphorus and other nutrients, wherein the starch content is 40%-80%, such as Chinese medicine residue containing components such as isatis root, white peony root, kudzu root, ginkgo, turmeric, peony bark, Poria, astragalus and the like and their mixtures.

[0033] Step S2: directly adding the Chinese medicinal residues without any pretreatment into the reactor, adding an appropriate amount of deionized water, adjusting the pH, and then performing a sterilization operation to obtain a Chinese medicinal residue culture medium.

[0034] In this step, since the Chinese medicine residue itself is rich in nutrients, in the process of preparing the Chinese medicine residue culture medium, it is not necessary to add any other nutrients except the Chinese medicine residue itself.

[0035] In this step, the Chinese medicinal residue without any pretreatment is directly added to the reactor, which is a large block of wet medicinal residue containing a large amount of water without any treatment after decoction. The solid-liquid ratio is adjusted so that the concentration of the dry matter is in the range of 50-200g / L and the pH range in the reactor is 5-6.5.

[0036] Step S3: inoculating the star yeast into a seed culture medium for cultivation to obtain an oil-producing microbial seed solution.

[0037] In a sterile operating environment, Staryi's oil yeast is inoculated into a nutrient-rich liquid seed culture medium and cultured with aeration at 25°C-35°C for 24-48 hours to obtain an oil-producing yeast seed liquid, wherein the liquid seed culture medium uses glucose or starch as the main carbon source and energy source, and then an appropriate amount of other nutrients such as yeast powder, peptone, corn steep liquor, etc. are added.

[0038] The Starch yeast used in this step can be directly purchased from strain collection institutions such as China General Microbiological Culture Collection (CGMCC), China Industrial Microbiological Culture Collection (CICC), American Type Culture Collection (ATCC), Agricultural Research Culture Collection (NRRL), UK National Strain Collection (UKNCC), Netherlands Microbiological Culture Collection (CBS), or German Microbiological Culture Collection (DSMZ), or separated from nature, and artificial or natural mutant strains with different properties from the original strain can also be used.

[0039] Step S4: inoculating the oil-producing microbial seed liquid obtained in step S3 into the Chinese medicine residue culture medium obtained in step S2, without adding or adding a small amount of cellulase, aerobically fermenting for a period of time at a suitable temperature, and terminating the fermentation when the Chinese medicine residue solids in the culture medium are degraded and the reducing sugar concentration in the fermentation liquid is lower than 5g / L. The solid phase containing the oil-producing yeast is collected by solid-liquid separation, and the solid-liquid separation can be carried out by centrifugation or filtration.

[0040] In this step, the volume of the oil-producing microbial seed liquid accounts for 2%-20% of the volume of the mixed culture medium, the added amount of the cellulase is 0-1 FPU / g of traditional Chinese medicine residue, and the culture temperature is controlled between 25°C and 35°C.

[0041] Step S5: separating the fermentation liquid into solid and liquid, collecting the solid phase where the oil-producing yeast is located, and then extracting microbial oil from the collected solid phase.

[0042] The solid phase obtained in the above steps is a mixture of microbial cells and Chinese medicine residues, from which oil is extracted, and the cell oil yield is calculated. The microbial oil is mainly glyceride of long-chain fatty acids and their derivatives, which can be made into biodiesel after transesterification, such as transesterification under acid catalysis to prepare biodiesel (this process is a conventional preparation process and will not be repeated here). In addition, the unsaturated fatty acids contained in the microbial oil can also be used to prepare other high value-added products.

[0043] The present invention is described below by means of specific examples. The following examples select typical examples of culturing typical oil-producing microorganisms using typical Chinese medicine residues as raw materials, which is helpful for understanding the present invention, but does not limit the application of the present invention to other materials or oil-producing strains in any form.

[0044] Embodiment 1:

[0045] 1. The water content of the ginkgo wet residue was 72.1%, and the mass of the ginkgo wet residue corresponding to 200 g / L of ginkgo residue dry matter was calculated;

[0046] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of ginkgo wet residue culture medium;

[0047] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0048] The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of ginkgo wet residue culture medium obtained in step 2, the inoculation amount is 10% (v / v), the amount of cellulase added is 1 FPU / g ginkgo residue, and the fermentation is terminated after aeration culture at 30°C for 96 hours. The solid phase containing the oil-producing yeast is collected by solid-liquid separation to obtain 47.5 g / L of dry bacteria and residual ginkgo residue. The conventional method is used to extract oil, and the oil yield obtained is 31.2 g / L.

[0049] Embodiment 2:

[0050] 1. The water content of the Pueraria root wet residue was 69.6%, and the mass of the Pueraria root wet residue corresponding to 200 g / L Pueraria root dry matter was calculated;

[0051] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of Pueraria lobata wet drug residue culture medium;

[0052] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0053] 4. The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of Pueraria lobata wet medicinal residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v) and an addition amount of cellulase of 1 FPU / g Pueraria lobata medicinal residue. The fermentation is terminated after aeration culture at 30°C for 96 hours, and the solid phase containing the oil-producing yeast is collected by solid-liquid separation to obtain a total of 46 g / L of dry bacteria and residual Pueraria lobata medicinal residue. The conventional method is used to extract oil, and the obtained oil yield is 26.8 g / L.

[0054] Embodiment 3:

[0055] 1. The water content of white peony root wet residue was 71.3%, and the mass of white peony root wet residue corresponding to 200 g / L white peony root dry matter was calculated;

[0056] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of white peony wet residue culture medium;

[0057] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0058] 4. The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of white peony wet residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v), and the amount of cellulase added is 1 FPU / g white peony residue. The fermentation is terminated after aeration culture at 30°C for 96 hours, and the solid phase containing the oil-producing yeast is collected by solid-liquid separation to obtain a total of 44.8 g / L of dry bacteria and residual white peony residue. The conventional method is used to extract oil, and the obtained oil yield is 21.1 g / L.

[0059] Embodiment 4:

[0060] 1. The water content of the Radix Isatidis wet residue is 72.5%, and the mass of the Radix Isatidis wet residue corresponding to 200 g / L of the Radix Isatidis dry matter is calculated;

[0061] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of Radix Isatidis wet residue culture medium;

[0062] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0063] 5. Inoculate the oil-producing microbial seed liquid obtained in step 3 into the large block of Isatis Radix wet residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v) and an added amount of cellulase of 1 FPU / g Isatis Radix residue. After aeration culture at 30°C for 96 hours, terminate the fermentation, collect the solid phase containing the oil-producing yeast by solid-liquid separation, and obtain 47.4 g / L of dry bacteria and residual Isatis Radix residue. Use conventional methods to extract oil, and the obtained oil yield is 17 g / L.

[0064] Embodiment 5:

[0065] 1. The water content of the turmeric wet residue is 73.2%, and the mass of the turmeric wet residue corresponding to 200 g / L of the dry matter of the turmeric residue is calculated;

[0066] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of turmeric wet residue culture medium;

[0067] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0068] 4. The oil-producing microbial seed liquid obtained in step 3 was inoculated into the large block of turmeric wet medicinal residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v), and the amount of cellulase added was 1 FPU / g turmeric medicinal residue. The fermentation was terminated after aeration culture at 30° C. for 96 h, and the solid phase containing the oil-producing yeast was collected by solid-liquid separation. The oil was extracted by conventional methods, and the yield of the obtained oil was 16.5 g / L.

[0069] Embodiment 6:

[0070] 1. The water content of the wet residue of Paeonia suffruticosa was 68.2%, and the mass of the wet residue of Paeonia suffruticosa corresponding to 200 g / L of the dry matter of the residue was calculated;

[0071] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of Paeonia suffruticosa wet residue culture medium;

[0072] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0073] 4. The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of peony bark wet residue culture medium obtained in step 2, the inoculation amount is 10% (v / v), the amount of cellulase added is 1 FPU / g peony bark residue, and the fermentation is terminated after aeration culture at 30°C for 96 hours. The solid phase containing the oil-producing yeast is collected by solid-liquid separation, and the oil is extracted by conventional methods. The resulting oil yield is 13.3 g / L.

[0074] Embodiment 7:

[0075] 1. The water content of the wet Poria residue was 69.9%, and the mass of the wet Poria residue corresponding to 200 g / L of dry matter of the Poria residue was calculated;

[0076] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of Poria cocos wet residue culture medium;

[0077] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0078] 4. The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of wet Poria cocos residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v) and an added amount of cellulase of 1 FPU / g Poria cocos residue. The fermentation is terminated after aeration culture at 30°C for 96 hours, and the solid phase containing the oil-producing yeast is collected by solid-liquid separation. The oil is extracted by conventional methods, and the oil yield is 14.2 g / L.

[0079] Embodiment 8:

[0080] 1. The water content of the wet Astragalus residue was 71.7%, and the mass of the wet Astragalus residue corresponding to 200 g / L dry matter of the Astragalus residue was calculated;

[0081] 2. Add it into the reactor and sterilize it at 121°C for 20 minutes to obtain a large block of Astragalus wet residue culture medium;

[0082] 3. Starch yeast AS2.1560 (China General Microbiological Culture Collection Management Center) was cultured in YPD medium (glucose 20 g / L, yeast powder 10 g / L, peptone 10 g / L), and cultured with shaking at 30°C and 200 rpm for 40 h to obtain an oil-producing microbial seed solution;

[0083] 4. The oil-producing microbial seed liquid obtained in step 3 is inoculated into the large block of wet astragalus residue culture medium obtained in step 2, with an inoculation amount of 10% (v / v) and an addition amount of cellulase of 1 FPU / g astragalus residue. The fermentation is terminated after aeration culture at 30°C for 96 hours, and the solid phase containing the oil-producing yeast is collected by solid-liquid separation. The oil is extracted by conventional methods, and the oil yield is 16.2 g / L.

[0084] Comparative Example 1:

[0085] 1. Dry the decocted Danshen wet residue in an oven at 80°C to constant weight, crush it with a grinder, pass it through a 40-mesh sieve, and store it in a glass jar;

[0086] 2. Put 100 g / L of Danshen residue into a blue-capped bottle, add 10 g / L sulfuric acid solution, the solid-liquid ratio is 1:10 (w / v), pretreat at 120°C for 60 min, adjust the pH to 4.8 with solid sodium hydroxide, and then directly perform enzymatic hydrolysis, wherein the addition amount of hemicellulase is 5 mg / g, the addition amount of cellulase is 10 FPU / g, and solid-liquid separation is performed to obtain Danshen culture medium, whose reducing sugar concentration is 34.2 g / L;

[0087] 3. Cultivate Trichosporon oleaginous yeast ATCC 20509 (China General Microbiological Culture Collection Management Center) in a seed culture medium (20 g / L glucose, 10 g / L yeast powder, 10 g / L peptone), shake culture at 30°C and 200 rpm for 24 h to obtain an oleaginous microbial seed solution;

[0088] 4. The oil-producing microbial seed liquid obtained in step 3 was inoculated into the oil-producing microbial culture medium in step 2 at an inoculation amount of 10% (v / v). The fermentation was terminated after aeration culture at 30°C for 144 hours. The solid phase containing the oil-producing yeast was collected by solid-liquid separation. The resulting oil yield was 6.5 g / L.

[0089] Comparative Example 2:

[0090] 1. Dry the decocted Sophora flavescens wet residue in an oven at 80°C to constant weight, crush it with a grinder, pass it through a 40-mesh sieve, and store it in a glass jar;

[0091] 2. Put 100 g / L of Sophora flavescens residue into a blue-capped bottle, add 10 g / L of sodium hydroxide solution, the solid-liquid ratio is 1:10 (w / v), pretreat at 120°C for 60 min, adjust the pH to 4.8 with hydrochloric acid, and then directly perform enzymatic hydrolysis, wherein the amount of starch degrading enzyme added is 150 mg / g, the amount of cellulase added is 10 FPU / g, and solid-liquid separation is performed to obtain Sophora flavescens culture medium, whose reducing sugar concentration is 48.3 g / L;

[0092] 3. Cultivate Trichosporon oleaginous yeast ATCC 20509 (China General Microbiological Culture Collection Management Center) in a seed culture medium (20 g / L glucose, 10 g / L yeast powder, 10 g / L peptone), shake culture at 30°C and 200 rpm for 24 h to obtain an oleaginous microbial seed solution;

[0093] 4. The oil-producing microbial seed liquid obtained in step 3 was inoculated into the oil-producing microbial culture medium in step 2 at an inoculation amount of 10% (v / v). The fermentation was terminated after aeration culture at 30°C for 144 hours. The solid phase containing the oil-producing yeast was collected by solid-liquid separation. The resulting oil yield was 7.2 g / L.

[0094] Comparative Examples 1 and 2 are conventional methods for treating and fermenting Chinese medicine residues. The main process is first crushing, then acid and alkali pretreatment, then preparing sugar solution by enzyme hydrolysis, and finally obtaining microbial oil by fermentation with oil-producing microorganisms. In this process, not only are the steps complicated, the equipment and enzyme costs are high, but also a large amount of acid and alkali are added, causing environmental pollution. Examples 1-8 use the highly integrated process of the present invention. The Starch oil yeast used can produce amylase by itself and quickly degrade starch. The present invention not only removes the process of acid and alkali pretreatment, but also highly integrates amylase production, enzyme hydrolysis of starch to prepare fermentable sugar, and oil-producing yeast oil fermentation. Compared with the comparative example, this reduces production costs and time costs, and provides a new method for the resource utilization of starch-rich plant-based Chinese medicine residues.

[0095] In addition, in the embodiments of the present invention, a small amount of cellulase is added to remove the cellulose part of the Chinese medicine residue that is not conducive to the hydrolysis of starch by amylase, thereby expanding the utilization of starch-rich plant-based Chinese medicine residue by Starch yeast and accelerating the accumulation efficiency of oil.

[0096] The present invention provides a method for producing oil by directly utilizing starch-rich plant-source Chinese medicine residues. The method provides a new idea and method for the treatment of the Chinese medicine residues. The method is simple and efficient to implement, and helps to solve the problems of complex process flow and high production cost in the current process of producing oil from Chinese medicine residues. The method has obvious comprehensive technical advantages.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for directly utilizing starch-rich plant-derived Chinese medicine residues to produce oil, characterized in that: The method comprises the following steps: Step S1: selecting Chinese medicinal residue raw materials, selecting plant-based wet Chinese medicinal residues with relatively high starch content; Step S2: directly adding the Chinese medicine residue without any pretreatment into the reactor, adding an appropriate amount of deionized water, adjusting to a suitable dry matter concentration, adjusting the pH to 5-6.5, and then performing a sterilization operation to obtain a Chinese medicine residue culture medium; Step S3: inoculating the star yeast into a seed culture medium for cultivation to obtain an oil-producing microbial seed solution; Step S4: inoculate the oil-producing microbial seed liquid obtained in step S3 into the Chinese medicinal residue culture medium obtained in step S2, add no or a small amount of cellulase, and aerobically ferment for a period of time at an appropriate temperature. When the Chinese medicinal residue solids in the culture medium are degraded and the reducing sugar concentration in the fermentation liquid is lower than 5 g / L, terminate the fermentation. Step S5: separating the fermentation liquid into solid and liquid, collecting the solid phase where the oil-producing yeast is located, and then extracting microbial oil from the collected solid phase.

2. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S1, the Chinese medicine residue contains various nutrients such as starch, cellulose, polysaccharides, protein, amino acids, crude fat, nitrogen, phosphorus, etc.

3. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S1, the starch-rich plant-based Chinese medicinal residue has a starch content of 40%-80%, such as Chinese medicinal residue containing components such as Radix Isatidis, Radix Paeoniae Alba, Radix Puerariae, Ginkgo, Curcuma Longa, Cortex Moutan, Poria, Radix Astragali and the like, and a mixture thereof.

4. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S2, the Chinese medicinal residue can be untreated large block wet medicinal residue, and the dry matter concentration thereof is in the range of 50-200 g / L.

5. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S2, since the Chinese herbal medicine residue itself is rich in nutrients, no other nutrients need to be added during the preparation of the starch-rich plant-source Chinese herbal medicine residue culture medium. At the same time, some carbon sources, nitrogen sources or inorganic salts can also be added to assist fermentation.

6. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S3, the oil-producing microorganism is the oil-producing yeast Lipomyces staryi and its natural mutants and engineered strains that can directly utilize starch.

7. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S4, the volume of the oil-producing microorganism seed liquid accounts for 2%-20% of the volume of the mixed culture medium, and the culture temperature is controlled between 25°C and 35°C.

8. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S4, cellulase may not be added, or a very small amount of cellulase (0-1 FPU / g) may be added to assist in the hydrolysis of the Chinese medicine residue.

9. The method for producing oil directly from starch-rich plant-derived Chinese medicinal residues as claimed in claim 1, characterized in that: In step S5, the extracted oil is one or more long-chain fatty acids and their derivatives, which are suitable as a substitute raw material for biodiesel.

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