Complex microbial inoculant containing brachybacterium and application of complex microbial inoculant

Abstract

The invention relates to the field of microbial engineering, and discloses a complex microbial inoculant containing brachybacterium and application of the complex microbial inoculant. The invention relates to a composite bacterial agent, which contains paracoccus (Paracoccus), Prostecobacter (Prostecobacter) and Ideonella (Ideonella). The complex microbial inoculant has high utilization rate of organic acid (especially valeric acid), and can rapidly adapt to mixed organic acid dominated by valeric acid for PHA synthesis, so that the raw material source of PHA is widened, and large-scale production of PHA is facilitated.

Description

Technical Field

[0001] The invention relates to the field of microbial engineering, and in particular to a composite bacterial agent containing Bacillus subtilis and uses thereof. Background Art

[0002] Petroleum-based traditional plastics have long been an indispensable material in the production and life of human beings around the world. From 1950 to 2015, a total of 8.3 billion virgin plastics have been produced worldwide. There is a lack of effective treatment methods for the large amount of plastic waste produced. From 1950 to 2015, about 4.6 billion tons of plastic waste were discarded or landfilled in natural systems. Due to the non-degradability of petroleum-based plastics, plastic waste in the natural environment seriously threatens the survival of wildlife and is enriched in the food chain in the form of "microplastics", which directly threatens human health. In order to reduce the plastic pollution caused by the use of petroleum-based plastics, the development of biodegradable "biodegradable plastics" is an important research direction. Among them, polyhydroxyalkanoic acid (PHA) is regarded as the most promising substitute for petroleum-based plastics due to its good biodegradability, biocompatibility and complete biosynthesis. At present, PHA is mainly synthesized by pure bacterial fermentation, but due to the need for refined substrates and strict sterilization environment, PHA still cannot be expanded for production and application. In order to reduce costs, various organic wastes (straw, kitchen waste, etc.) will be used as low-cost alternative substrates. In actual application, organic wastes are first converted into various short-chain organic acids (acetic acid, propionic acid, butyric acid, valeric acid and lactic acid, etc.) through anaerobic fermentation, and then supplied to various PHA-synthesizing microorganisms for PHA synthesis.

[0003] At present, the bacteria commonly used for PHA biosynthesis mainly come from Azoarcus, Paracoccus, Pseudofulvimonas, Amaricoccus, etc. In the actual anaerobic fermentation process, if the sugar content in the organic waste is high, the acid composition of the organic acid produced is often acetic acid and propionic acid as the main organic acid components. It is difficult for current PHA synthesizing microorganisms to efficiently utilize acetic acid and propionic acid while also utilizing other organic acids (n-butyric acid, n-valeric acid and lactic acid). Therefore, it is of great significance to develop a bacterial agent that can efficiently utilize organic acids (especially mixed organic acids dominated by acetic acid and propionic acid) for PHA synthesis. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that it is difficult to efficiently utilize organic acids in the prior art, and to provide a composite bacterial agent containing Bacillus thuringiensis and its use.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides a composite bacterial agent containing Prosthecobacter, wherein the composite bacterial agent contains Paracoccus, Prosthecobacter and Ideonella.

[0006] The second aspect of the present invention provides a method for preparing polyhydroxyalkanoate, which comprises: inoculating the above-mentioned composite bacterial agent into a fermentation medium for fermentation to obtain a fermentation product containing polyhydroxyalkanoate.

[0007] The third aspect of the present invention provides the use of bacteria or composite bacterial agents in synthesizing polyhydroxyalkanoates using organic acids.

[0008] Through the above technical scheme, the composite bacterial agent of the present invention has a high utilization rate of organic acids (especially valeric acid), and can quickly adapt to the synthesis of PHA with mixed organic acids dominated by valeric acid, thereby broadening the raw material source of PHA and being more conducive to the large-scale production of PHA. DETAILED DESCRIPTION

[0009] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0010] The composite bacterial agent provided by the present invention contains Paracoccus, Bacillus and Aideon. As long as the different microorganisms as described above are combined, the utilization rate of organic acids (especially valeric acid) can be effectively improved, and there is no special requirement for the ratio of each microorganism, but preferably, the ratio of the cell dry weight of Paracoccus and Aideon in the composite bacterial agent is 10-40:1, more preferably 15-30:1.

[0011] Preferably, the ratio of the dry cell weight of Bacillus subtilis and Ideonella in the composite bacterial agent is 0.2-2:1, more preferably 0.5-1.5:1.

[0012] The specific strain of the Paracoccus in the present invention may be a common strain in the art. Preferably, the Paracoccus is at least one of Paracoccus aurantiacus, Paracoccus sanguinis and Paracoccus mangrovi.

[0013] More preferably, the Paracoccus is Paracoccus aureus, Paracoccus sanguineus and Paracoccus marienii.

[0014] Further preferably, the ratio of the dry cell weight of Paracoccus aureus to Paracoccus martensii is 5-20:1, more preferably 7-18:1.

[0015] Further preferably, the ratio of the dry cell weight of Paracoccus sanguinis to Paracoccus martensii is 1-5:1, more preferably 1.5-4:1.

[0016] In the present invention, the specific strain of Paracoccus aureus may be a common strain in the art. Preferably, the Paracoccus aureus is Paracoccus aureus CGMCC 1.13898 (PA for short, from the General Microbiology Center of China National Microbiological Culture Collection Committee (CGMCC)).

[0017] In the present invention, the specific strain of the Paracoccus sanguinis may be a common strain in the art. Preferably, the Paracoccus sanguinis is Paracoccus sanguinis DSM 29303 (PS for short, from the German Collection of Microorganisms).

[0018] In the present invention, the specific strain of Paracoccus martensii may be a common strain in the art. Preferably, the Paracoccus martensii is Paracoccus martensii BCRC 80920 (PM for short, Taiwan Biological Resources Collection, Taiwan, China).

[0019] In the present invention, the specific strain of Prosthecobacter can be a common strain in the art. Preferably, the Prosthecobacter is Prosthecobacter vanneervenii. More preferably, the Prosthecobacter vanneervenii is Prosthecobacter vanneervenii ATCC 700199 (abbreviated as PV, from the American Type Culture Collection).

[0020] In the present invention, the specific strain of Ideonella can be a common strain in the art. Preferably, the Bacillus livida is Ideonella livida, and more preferably, the Ideonella livida is Ideonella livida BCRC 81199 (abbreviated as IL, from Taiwan Biological Resources Collection, Taiwan, China).

[0021] The composite bacterial agent of the present invention can efficiently utilize organic acid to synthesize PHA. Therefore, the method for preparing PHA provided by the present invention comprises: inoculating the composite bacterial agent as described above into a fermentation medium for fermentation to obtain a fermentation product containing PHA.

[0022] According to the present invention, the carbon source and inorganic salt in the fermentation medium can be substances commonly used in the art that can provide C and inorganic salt (trace elements), respectively.

[0023] According to a preferred embodiment of the present invention, the carbon source in the fermentation medium is an organic acid, which can be an organic acid commonly used in the art for fermentation to produce PHA, more preferably a monoacid with a carbon number of 1-5 (such as 1, 2, 3, 4, 5) (such as at least one (or all) of acetic acid, propionic acid, n-butyric acid, n-valeric acid and lactic acid), further preferably a monoacid with a carbon number of 4-6, and most preferably valeric acid. The organic acid can be provided by a mixed organic acid containing a plurality of organic acids (acetic acid, propionic acid, n-butyric acid, n-valeric acid and lactic acid), such as an anaerobic fermentation product of organic waste (various crop straws, kitchen waste and / or mixtures thereof), thereby further broadening the raw material source of PHA and reducing the synthesis cost of PHA. According to a preferred embodiment of the present invention, in the fermentation medium, the contents of acetic acid, propionic acid, butyric acid, valeric acid and lactic acid are each independently in the range of 0.2-5 g / L, preferably 0.7-4.5 g / L.

[0024] The anaerobic fermentation process of organic waste (various crop straws, food waste and / or mixtures thereof, etc.) can be carried out in a common manner in the art, and the anaerobic fermentation method can be medium temperature (37°C) / high temperature (55°C) continuous anaerobic fermentation.

[0025] According to a preferred embodiment of the present invention, the content of carbon source in the fermentation medium is 2-25 g / L.

[0026] According to a preferred embodiment of the present invention, the fermentation medium may also contain organic amines to inhibit denitrification, but the total content of nitrogen in the fermentation medium is less than 20 mg / L. The content of the organic amines may be 50-170 mg / L, and the organic amines may be selected from ethylenediaminetetraacetic acid and / or thiourea. More preferably, each liter of the fermentation medium contains 0.05-0.15 g of ethylenediaminetetraacetic acid. More preferably, each liter of the fermentation medium contains 5-15 mg of thiourea. Further preferably, the fermentation medium also contains ethylenediaminetetraacetic acid and thiourea. According to a preferred embodiment of the present invention, the fermentation medium does not contain common nitrogen sources used for bacterial culture (such as corn steep liquor, peptone, yeast powder, urea, ammonium sulfate, ammonia, nitrates, etc.).

[0027] According to the present invention, the inorganic salt in the fermentation medium can mainly provide trace elements, and can be various water-soluble inorganic salts commonly used in the art. In a preferred embodiment of the present invention, the inorganic salt in the fermentation medium includes at least one of magnesium salts, calcium salts, potassium salts, iron salts, copper salts, manganese salts, sodium salts, zinc salts, and cobalt salts, and more preferably includes at least one of magnesium sulfate, calcium chloride, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, thiourea, ferric chloride, copper sulfate, potassium iodide, manganese chloride, sodium molybdate, zinc sulfate, and cobalt chloride.

[0028] According to a preferred embodiment of the present invention, the content of inorganic salts in the fermentation medium is 0.2-3 g / L.

[0029] More preferably, the fermentation medium contains 0.2-0.7 g of magnesium sulfate per liter.

[0030] More preferably, the fermentation medium contains 0.03-0.2 g of calcium chloride per liter.

[0031] More preferably, the fermentation medium contains 0.01-0.2 g of dipotassium hydrogen phosphate per liter.

[0032] More preferably, the fermentation medium contains 0.01-0.1 g of potassium dihydrogen phosphate per liter.

[0033] More preferably, the fermentation medium contains 0.7-3 mg of ferric chloride per liter.

[0034] More preferably, each liter of the fermentation medium contains 0.02-0.1 mg of copper sulfate.

[0035] More preferably, each liter of the fermentation medium contains 0.02-0.1 mg potassium iodide.

[0036] More preferably, the fermentation medium contains 0.05-0.3 mg manganese chloride per liter.

[0037] More preferably, each liter of the fermentation medium contains 0.04-0.2 mg of sodium molybdate.

[0038] More preferably, the fermentation medium contains 0.06-0.4 mg zinc sulfate per liter.

[0039] More preferably, the fermentation medium contains 0.06-0.5 mg of cobalt chloride per liter.

[0040] According to a preferred embodiment of the present invention, the fermentation medium further contains boric acid, and more preferably, each liter of the fermentation medium contains 0.06-0.5 mg of boric acid.

[0041] According to a particularly preferred embodiment of the present invention, each liter of fermentation medium contains 2-25 g of organic acid, 0.2-0.7 g of magnesium sulfate, 0.05-0.15 g of ethylenediaminetetraacetic acid, 0.03-0.2 g of calcium chloride, 0.01-0.2 g of dipotassium hydrogen phosphate, 0.01-0.1 g of potassium dihydrogen phosphate, 5-15 mg of thiourea, 0.7-3 mg of ferric chloride, 0.06-0.5 mg of boric acid, 0.02-0.1 mg of copper sulfate, 0.02-0.1 mg of potassium iodide, 0.05-0.3 mg of manganese chloride; 0.04-0.2 mg of sodium molybdate, 0.06-0.4 mg of zinc sulfate, and 0.06-0.5 mg of cobalt chloride.

[0042] According to the present invention, the initial pH value of the fermentation medium may be 6-8, preferably 7±0.1.

[0043] According to the present invention, the fermentation can be carried out under conditions that are conducive to the synthesis of PHA by the microorganisms in the composite bacterial agent. Preferably, the fermentation conditions include: a temperature of 20-35°C and a time of 2-10 hours. The fermentation is preferably carried out under aerobic conditions, preferably, the oxygen content is ≥4 mg / L, more preferably 6-8 mg / L.

[0044] According to the present invention, the inoculation amount of the composite bacterial agent can be 4000-10000 mg of dry cell weight per liter of fermentation medium.

[0045] According to the present invention, before fermentation, the method may further include: the steps of activating and amplifying the composite bacterial agent (pre-culture), wherein the activation can restore the dormant microorganisms to a normal living state, usually on a solid culture medium. The amplification can increase the total amount and concentration of the microorganisms so as to meet the fermentation requirements, usually in a liquid culture medium. The activation and amplification can be performed in a manner commonly used in the art, for example, LB culture medium can be used.

[0046] According to the method of the present invention, organic acids are used to synthesize PHA, and the utilization rate of organic acids is relatively high, especially valeric acid. When mixed organic acids containing valeric acid are fermented, the consumption rate of valeric acid is greater than 330 mg / L / h.

[0047] The inventors of the present invention first discovered that Paracoccus, Bacillus and Ideon (or the composite bacterial agent) can metabolize organic acids as carbon sources to produce PHA. Therefore, the present invention also provides the use of bacteria or composite bacterial agents in synthesizing PHA using organic acids, characterized in that the bacteria are selected from at least one of Paracoccus, Bacillus and Ideon as described above, and the composite bacterial agent is the composite bacterial agent as described above. The specific types of the organic acid are as described above and will not be repeated here.

[0048] The present invention will be described in detail below through examples. In the following embodiments, the method for determining the cell dry weight is a drying weighing method (10 ml of fermentation broth is centrifuged at 10,000 rpm, the supernatant is removed, and the biomass is then placed at 105° C. for drying for 12 h); the method for detecting the organic acid content in the fermentation broth is a high performance liquid chromatography detection method; the method for detecting the proportion of PHA in the cell is a gas chromatography-mass spectrometry detection method (based on trihydroxybutyric acid monomer and trihydroxyvaleric acid monomer): the fermentation broth is taken, centrifuged at 10,000 rpm, the supernatant is removed, the biomass is frozen at -80° C., and then freeze-dried to remove moisture; the dried biomass is placed in a glass digestion tube, 2 ml of acidified methanol (5% sulfuric acid) and 2 ml of chloroform are added; hydrolyzed at 105° C. for 6 hours; 1 mL of water is then added to the hydrolyzate, fully shaken, and after standing and stratification, 1 μL of the lower chloroform phase is taken; it is placed on a GCMS for detection; the standard curve is constructed using trihydroxybutyric acid monomer and trihydroxyvaleric acid monomer standards purchased from Sigma by the above method.

[0049]

[0050]

[0051] Example 1

[0052] (1) Culture medium

[0053] Culture medium 1 (1 L): 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, pH = 7.4.

[0054] Medium 2 (1 L): MgSO 4 7H 2 O, 0.67g; EDTA, 0.11g; CaCl 2 ·2H 2 O, 0.08g; K 2 HPO 4 , 0.048g; KH 2 PO 4 , 0.038g; thiourea, 10mg; culture medium 3, 1mL.

[0055] Medium 3 (1 L): FeCl 3 6H 2 O, 1.5 g; H 3 BO 3 , 0.15g; CuSO 4 ·5H 2 O, 0.03 g; KI, 0.03 g; MnCl 2 ·4H 2 O, 0.12g; Na 2 MoO 4·2H 2 O, 0.06g; ZnSO 4 7H 2 O, 0.12 g; CoCl 2 6H 2 O, 0.15g.

[0056] (2) Strain activation and pre-culture

[0057] PA, PS, PV, IL and PM strains were inoculated on the solid medium of medium 1 (agar addition amount was 18 g / L) and activated at 37°C for 24 hours, and then inoculated into medium 1 (liquid medium) for 24 hours of pre-culture at 26°C. The pre-cultured bacterial solution was centrifuged at 8000g for 2 minutes, the bacteria were collected, and the composite bacterial agent was prepared according to the following cell dry weight ratio: PA (72%), PS (14%), PV (4%), IL (4%), PM (6%).

[0058] Example 2

[0059] This example is used to illustrate the method of using artificial bacteria to synthesize PHA using mixed organic acids. The specific operation is as follows:

[0060] In order to illustrate that the composite bacterial agent of the present invention can specifically and efficiently utilize acetic acid and propionic acid, the bacterial agent is used in the presence of mixed organic acids (acetic acid, propionic acid, n-butyric acid, n-valeric acid and lactic acid) in a 400mL fermenter (inoculation amount is 5000mg cell dry weight / L) for aerobic fermentation. The fermentation adopts 3h batch fermentation, the fermentation temperature is 26°C, and the oxygen content in the system is controlled to 6-8mg / L; the corresponding organic acid is added to the culture medium 2 and the pH is adjusted to 7±0.1 with sodium hydroxide as the fermentation medium, and the concentration of different organic acids in the fermentation medium is shown in Table 1; during the fermentation process, the organic acid content in the fermentation broth and the proportion of PHA in the cells are sampled and measured, and the results are shown in Table 2.

[0061] Table 1 Composition of mixed organic acids

[0062]

[0063]

[0064] Table 2 Mixed organic acid batch fermentation experimental results

[0065]

[0066] The above experimental results show that the consumption rate of valeric acid is relatively fast, whether in the start-up phase of 0.5h before fermentation or in the overall 3h. After 3h of fermentation, the weight content of PHA in the cells increased from 10.2% of the cell dry weight to 52% of the cell dry weight, and the contribution rate of valeric acid to the increase of PHA was the highest at 44%. Therefore, this strain can preferentially use valeric acid in mixed acid for PHA synthesis.

[0067] Example 3

[0068] This embodiment provides a method for synthesizing PHA using an artificial bacterial community using a mixed acid mainly composed of valeric acid, and the specific operation is as follows:

[0069] In order to detect the maximum accumulation capacity of PHA of the composite bacterial agent of the present invention using a mixed organic acid mainly composed of valeric acid, repeated batch fermentation was carried out in a 400 mL aerobic fermenter using mixed organic acids (inoculation amount was 5000 mg cell dry weight / L), the fermentation temperature was 26 ° C, the oxygen content in the system was controlled to 6-8 mg / L, each batch was 1 hour, and repeated 5 times, the specific operation was as follows:

[0070] First batch: After inoculating the fermenter with the bacterial agent and adding the culture medium, ferment for one hour, let it stand for 30 minutes, let the bacteria sink, and remove 200 mL of the supernatant.

[0071] Second batch: Add 200 mL of new culture medium to the fermenter, ferment for one hour, let stand for 30 minutes, allow the bacteria to sink, and remove 200 mL of supernatant.

[0072] Third batch: Repeat the second batch operation.

[0073] Fourth batch: Repeat the second batch operation.

[0074] The fifth batch: add 200 mL of new culture medium to the fermenter, ferment for one hour, collect the bacteria, and complete the fermentation.

[0075] Among them, the corresponding organic acid was added to the culture medium 2 and the pH was adjusted to 7±0.1 with sodium hydroxide as the fermentation medium. The specific composition of the organic acid in the fermentation medium is shown in Table 3. During the fermentation process, samples were taken to determine the organic acid content in the fermentation broth and the proportion of PHA in the cells.

[0076] Table 3 Composition of mixed organic acids mainly composed of valeric acid

[0077] Organic Acid Mass concentration (mg / L) Acetic acid 250 Propionic acid 250 Butyric acid 250 Valeric acid 4000 lactic acid 250

[0078] The experimental results show that after 5 batches of fermentation, the weight content of PHA in the cells increased from 8.1% of the cell dry weight to 56.1% of the cell dry weight, of which polytrihydroxybutyric acid PHB (calculated as trihydroxybutyric acid monomer) accounted for 5% of the cell dry weight, and polytrihydroxyvaleric acid PHV (calculated as trihydroxyvaleric acid monomer) accounted for 51.1% of the cell dry weight. By calculating the mass ratio of carbon in the PHA increment to the mass ratio of carbon in the consumed organic acid, the bacterial system can convert 74.6% of the carbon in the organic acid in the fermentation system into PHA and store it in the cells. Therefore, the artificial bacterial system can efficiently use mixed acids mainly composed of valeric acid for PHA synthesis.

[0079] The inventors of the present invention also found that after the fermentation was completed, the proportion of each strain in the system was equivalent to that at the time of inoculation, which showed that the various strains worked synergistically to improve the utilization rate of organic acids (especially valeric acid).

[0080] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A composite bacterial agent containing Bacillus subtilis, It is characterized in that The composite bacterial agent contains Paracoccus, Prosthecobacter and Ideonella.

2. The composite bacterial agent according to claim 1, in, The cell dry weight ratio of Paracoccus, Bacillus subtilis and Aideonella in the composite bacterial agent is 10-40:0.2-2:

1.

3. The composite bacterial agent according to claim 1, in, The cell dry weight ratio of Paracoccus, Bacillus subtilis and Aideonella in the composite bacterial agent is 15-30:0.5-1.5:

1.

4. The composite bacterial agent according to claim 1, in, The paracoccus is at least one of Paracoccus aurantiacus, Paracoccus sanguinis and Paracoccus mangrovi; Preferably, the Paracoccus is Paracoccus aureus, Paracoccus sanguineus and Paracoccus martensii; More preferably, the ratio of the dry cell weights of Paracoccus aureus, Paracoccus sanguineus and Paracoccus martensii is 5-20:1-5:1, more preferably 7-18:1.5-4:1; And / or, the Prosthecobacter is Prosthecobacter vanneervenii; And / or, the Ideonella is Ideonella livida.

5. The composite bacterial agent according to claim 4, in, The Paracoccus aureus is Paracoccus aureus CGMCC:1.13898; And / or, the Paracoccus sanguineus is Paracoccus sanguineus DSM: 29303; And / or, the Paracoccus martensii is Paracoccus martensii BCRC:80920; And / or, the Bacillus vannivi is Bacillus vannivi ATCC: 700199; And / or, the Aedeon bacterium is Aedeon bacterium BCRC:81199.

6. A method for preparing polyhydroxyalkanoate, It is characterized in that The method comprises: inoculating the composite bacterial agent described in any one of claims 1 to 5 into a fermentation medium for fermentation to obtain a fermentation product containing polyhydroxyalkanoate.

7. The method according to claim 6, in, The carbon source in the fermentation medium is an organic acid, preferably a monobasic acid having 1 to 6 carbon atoms, more preferably n-valeric acid; And / or, the content of carbon source in the fermentation medium is 2-25 g / L.

8. The method according to claim 6, in, The fermentation medium further contains an organic amine, preferably, the organic amine is a diamine having a carbon number ≤ 15, more preferably, the organic amine is thiourea and / or ethylenediaminetetraacetic acid; And / or, the content of organic amine in the fermentation medium is 55-180 mg / L.

9. The method according to claim 6, in, The inorganic salt in the fermentation medium includes at least one of magnesium salt, calcium salt, potassium salt, iron salt, copper salt, manganese salt, sodium salt, zinc salt and cobalt salt; And / or, the inorganic salt content in the fermentation medium is 0.2-3 g / L.

10. The method according to claim 6, in, Each liter of fermentation medium contains 2-25g of organic acid, 0.2-0.7g of magnesium sulfate, 0.05-0.15g of ethylenediaminetetraacetic acid, 0.03-0.2g of calcium chloride, 0.01-0.2g of dipotassium hydrogen phosphate, 0.01-0.1g of potassium dihydrogen phosphate, 5-15mg of thiourea, 0.7-3mg of ferric chloride, 0.06-0.5mg of boric acid, 0.02-0.1mg of copper sulfate, 0.02-0.1mg of potassium iodide, 0.05-0.3mg of manganese chloride; 0.04-0.2mg of sodium molybdate, 0.06-0.4mg of zinc sulfate, and 0.06-0.5mg of cobalt chloride; and / or, the initial pH value of the fermentation medium is 6-8; And / or, the fermentation conditions include: temperature of 20-35°C, fermentation time of 2-10h, oxygen content ≥4mg / L.

11. Use of bacteria or composite bacterial agents in the synthesis of polyhydroxyalkanoates using organic acids, It is characterized in that The bacteria are selected from Bacillus subtilis and / or Aideonella in the composite bacterial agent described in any one of claims 1-5, and the composite bacterial agent is the composite bacterial agent described in any one of claims 1-5.

12. The use according to claim 11, in, The bacteria or composite bacterial agent metabolizes the organic acid as a carbon source to produce polyhydroxyalkanoate; And / or, the organic acid is selected from monobasic acids having 1 to 5 carbon atoms, preferably valeric acid.

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