Bacterial system for synthesizing PHA (polyhydroxyalkanoate) by efficiently utilizing mixed acid mainly containing butyric acid and application of bacterial system

Abstract

The invention relates to the technical field of microbial fermentation, in particular to a bacterial system for synthesizing PHA by efficiently utilizing mixed acid mainly containing butyric acid and application of the bacterial system. According to the present invention, the fermentation strain composition comprises Aromatobacterium Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC (China General Microbiological Culture Collection Center) 1.13898, Pseudofulvimonas gallinae DSM 21944 and Hydrophagocystis lecticum KCTC 32195, and the PHA can be efficiently synthesized by using the mixed organic acid mainly comprising butyric acid through the fermentation strain composition provided by the invention;

Description

Technical Field

[0001] The present invention relates to the technical field of microbial fermentation, and particularly relates to a bacterial strain for efficiently synthesizing PHA by using mixed acids mainly composed of butyric acid and its application. Background Art

[0002] The production and use of petroleum-based traditional plastics have led to the generation of a large amount of plastic waste. Due to the lack of effective treatment methods, most of these plastic wastes are discarded or landfilled. However, due to the non-degradability of petroleum-based plastics, plastic wastes in the natural environment seriously threaten the survival of wild animals and accumulate in the food chain in the form of "microplastics", thus directly threatening human health. Therefore, the development of biodegradable plastics is of great significance for reducing the production and use of petroleum-based plastics. Polyhydroxyalkanoates (PHA) have the characteristics of good biodegradability, biocompatibility and complete biosynthesis, and are regarded as the most potential substitutes for petroleum-based plastics. At present, PHA is mainly synthesized by pure bacteria fermentation. However, due to the need for refined substrates and a strictly sterile environment, PHA still cannot be produced and applied on a large scale. To reduce the production cost of PHA, various organic wastes (such as straw, food waste, etc.) will be used as low-cost alternative substrates. The organic wastes are first anaerobically fermented into various short-chain organic acids (acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, etc.) and then supplied to various PHA-synthesizing microorganisms for PHA synthesis. The bacteria commonly used for PHA biosynthesis mainly come from the genera Azoarcus, Paracoccus, Pseudofulvimonas, Amaricoccus, etc.

[0003] In the actual anaerobic fermentation process of organic wastes, under certain conditions, the organic acids produced are mixed organic acids mainly composed of butyric acid. However, it is difficult for a single bacterial strain to efficiently utilize butyric acid while also utilizing other organic acids (acetic acid, propionic acid, valeric acid and lactic acid). Therefore, it is necessary to develop a mixed bacterial strain that can efficiently utilize mixed organic acids mainly dominated by butyric acid for PHA synthesis. Summary of the Invention

[0004] The present invention provides a bacterial strain for efficiently synthesizing PHA by using mixed acids mainly composed of butyric acid and its application.

[0005] For the development of mixed fermentation strains for PHA synthesis, the prior art mostly enriches PHA-producing mixed flora through activated sludge. However, the mixed flora obtained by enriching activated sludge contains various known and unknown microorganisms. When using a mixed acid dominated by butyric acid, the activity is inhibited and the PHA synthesis efficiency is low. The present invention develops an artificial bacterial system with a clear and simple composition for PHA production for mixed organic acid substrates dominated by butyric acid. During the research and development process, it was unexpectedly found that combining Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 can efficiently utilize a mixed organic acid dominated by butyric acid and containing lactic acid, acetic acid, propionic acid, and valeric acid to synthesize PHA. The rate of utilization of butyric acid by this mixed strain is significantly higher than that of other organic acids, and it can also utilize lactic acid, acetic acid, propionic acid, and valeric acid at the same time, and is particularly suitable for fermenting and producing PHA using a mixed organic acid dominated by butyric acid as a substrate.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] The present invention provides a fermentation strain composition, which comprises Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195.

[0008] In the above strain composition, Aromatoleum Toluvorans DSM 15124 is an aerobic bacterium isolated from humus soil and is mainly used as a denitrifying bacterium for degrading aromatic compounds; Paracoccus sanguinis DSM 29303 is a Gram-negative, non-motile, rod-shaped bacterium isolated from clinical samples; Paracoccus aurantiacus CGMCC 1.13898 is a strain isolated from seawater in a shallow hydrothermal system near Guishan Island; Pseudofulvimonas gallinarii DSM 21944 is a Gram-negative, rod-shaped, oxidase-positive, non-spore-forming bacterium isolated from the air in livestock and poultry farms; Hydrogenophaga electricum KCTC 32195 is a bacterium isolated from the anodic biofilm of an acetate-filled microbial fuel cell. None of the above strains are known to be used for PHA synthesis or production. However, the present invention unexpectedly finds that their combined use can efficiently utilize a mixed organic acid dominated by butyric acid for fermentative production of PHA.

[0009] Preferably, in the fermentation strain composition, the dry cell weight ratios of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 45-55%, 40-50%, 1-5%, 1-5%, and 1-3%, respectively.

[0010] More preferably, in the fermentation strain composition, the dry cell weight ratios of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 45-49%, 43-48%, 2-3%, 2.5-3.5%, and 1.5-2.5%, respectively.

[0011] Inoculate for fermentation within the above-mentioned cell dry weight ratio range. Each of the above-mentioned strains can not only grow rapidly, but also cooperate more effectively, improve the efficiency of synthesizing PHA using organic acids such as butyric acid, and especially ensure the efficient utilization of butyric acid to synthesize PHA, so that the mixed organic acid substrate dominated by butyric acid can be effectively utilized.

[0012] The fermentation strain composition described in the present invention is preferably a fermentation strain composition for PHA synthesis. More preferably, it is a fermentation strain composition for synthesizing PHA using a mixed organic acid mainly composed of butyric acid.

[0013] In the present invention, the fermentation strain composition can be prepared into a liquid bacterial agent (such as a bacterial solution) or a solid bacterial agent (such as freeze-dried bacterial powder).

[0014] The present invention provides the application of the above-mentioned fermentation strain composition in PHA production.

[0015] In the above application, the fermentation strain composition serves as the fermentation strain for PHA production.

[0016] Preferably, the carbon source for PHA production contains organic acids.

[0017] Preferably, the organic acid is a mixed organic acid containing butyric acid.

[0018] Preferably, in the mixed organic acid, the content of butyric acid is higher than that of other organic acids.

[0019] Further preferably, the mixed organic acid contains butyric acid and one or more selected from lactic acid, acetic acid, propionic acid, and valeric acid.

[0020] In some embodiments of the present invention, the mixed organic acid contains butyric acid, lactic acid, acetic acid, propionic acid, and valeric acid.

[0021] In the above application, the fermentation substrate for PHA production can be the anaerobic fermentation broth of organic waste (such as straw, food waste, etc.), which contains butyric acid, lactic acid, acetic acid, propionic acid, and valeric acid, and the content of butyric acid is higher than that of lactic acid, acetic acid, propionic acid, and valeric acid.

[0022] The present invention provides the application of the above-mentioned fermentation strain composition in preparing a fermentation strain for PHA production.

[0023] The fermentation strain composition provided by the present invention can be used alone as the fermentation strain for PHA production or in combination with other PHA fermentation strains.

[0024] The present invention provides a method for fermentatively producing PHA, which includes the step of culturing the above-mentioned fermentation strain composition to obtain a culture containing PHA.

[0025] Preferably, the cultivation includes fermentation cultivation, and the carbon source for the fermentation cultivation contains organic acids.

[0026] Preferably, the organic acid is a mixed organic acid containing butyric acid, and in the mixed organic acid, the content of butyric acid is higher than that of other organic acids.

[0027] More preferably, the mixed organic acid contains butyric acid and one or more selected from lactic acid, acetic acid, propionic acid, and valeric acid.

[0028] In some embodiments of the present invention, the mixed organic acid contains butyric acid, lactic acid, acetic acid, propionic acid, and valeric acid.

[0029] In the above method, the fermentation substrate for PHA production can be the anaerobic fermentation broth of organic waste (such as straw, food waste, etc.), which contains butyric acid, lactic acid, acetic acid, propionic acid, and valeric acid, and the content of butyric acid is higher than that of lactic acid, acetic acid, propionic acid, and valeric acid.

[0030] Preferably, the temperature of the fermentation cultivation is 25 - 28 °C, the pH is 6.8 - 7.2, and the dissolved oxygen is 3 - 8 mg / L.

[0031] More preferably, the temperature of the fermentation cultivation is 25 - 27 °C, the pH is 6.9 - 7.1, and the dissolved oxygen is 4 - 7 mg / L.

[0032] Preferably, the inoculation amount of the fermentation cultivation is 4000 - 6000 mg cell dry weight / L.

[0033] The above cultivation may further include the steps of activating and pre - culturing the fermentation strains. Preferably, Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are separately activated and pre - cultured, and then mixed and inoculated into the fermentation medium according to a ratio.

[0034] In some embodiments of the present invention, the fermentation medium contains inorganic salts in addition to the mixed organic acids, or contains inorganic salts, EDTA and thiourea. Preferably, the fermentation medium contains mixed organic acids and MgSO4, EDTA, CaCl2, K2HPO4, KH2PO4, thiourea, FeCl3, H3BO3, CuSO4, KI, MnCl2, Ma2MoO, ZnSO4 and CoCl2.

[0035] In some embodiments of the present invention, the fermentation medium contains: acetic acid 200 - 300 mg / L, propionic acid 200 - 300 mg / L, lactic acid 200 - 300 mg / L, valeric acid 200 - 300 mg / L, butyric acid 3000 - 5000 mg / L, and MgSO4·7H2O 0.5 - 0.8 g / L, EDTA 0.1 - 0.15 g / L, CaCl2·2H2O 0.05 - 0.15 g / L, K2HPO4 0.04 - 0.08 g / L, KH2PO4 0.03 - 0.05 g / L, thiourea 5 - 15 mg / L, FeCl3·6H2O 1 - 2 mg / L, H3BO3 0.1 - 0.2 mg / L, CuSO4·5H2O 0.02 - 0.04 mg / L, KI 0.02 - 0.04 mg / L, MnCl2·4H2O 0.1 - 0.2 mg / L, Ma2MoO·2H2O 0.05 - 0.07 mg / L, ZnSO4·7H2O 0.1 - 0.2 mg / L, CoCl2·6H2O 0.1 - 0.2 mg / L.

[0036] The beneficial effects of the present invention at least include: the fermentation strain composition provided by the present invention can efficiently utilize mixed organic acids dominated by butyric acid to synthesize PHA, and has a high PHA yield and conversion rate. The fermentation strain composition is suitable for fermenting and producing PHA with mixed organic acids dominated by butyric acid generated by anaerobic fermentation of organic waste as the substrate, which is beneficial to improving the utilization rate of organic acids and the production efficiency of PHA, reducing the production cost of PHA and simplifying its fermentation process, and has a good application prospect. Detailed implementation manners

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0038] The medium formulations used in the following examples are as follows:

[0039] Medium1 (1L): 10 g of tryptone, 5 g of yeast extract, 10 g of sodium chloride, pH 7.4.

[0040] Medium2 (1L): 0.67 g of MgSO4·7H2O; 0.11 g of EDTA; 0.08 g of CaCl2·2H2O; 0.048 g of K2HPO4; 0.038 g of KH2PO4; thiourea (10 mg); 1 mL of Medium3.

[0041] Medium3 (1L): 1.5 g of FeCl3·6H2O; 0.15 g of H3BO3; 0.03 of CuSO4·5H2O; 0.03 g of KI; 0.12 g of MnCl2·4H2O; 0.06 g of Ma2MoO·2H2O; 0.12 g of ZnSO4·7H2O; 0.15 g of CoCl2·6H2O.

[0042] Example 1: Activation and pre-cultivation of strains

[0043] Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC32195 were respectively activated aerobically on the solid medium of Medium1 at 37°C for 24 h, and then inoculated into the liquid medium of Medium1 respectively, and pre-cultured for 24 h under aerobic conditions at 26°C. The pre-cultured bacterial solution was centrifuged at 8000×g for 2 min to collect the bacterial cells for subsequent preparation of the fermentation strain composition.

[0044] Example 2: Detection of the fermentation strain composition and its organic acid utilization efficiency

[0045] This embodiment provides a fermentation bacterial strain composition, which comprises Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195. Among them, the proportion of the dry cell weight of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 49.0%, 43%, 3.0%, 3.0%, and 2.0% respectively.

[0046] The above fermentation bacterial strain composition can be obtained by mixing the bacterial cells pre-cultured from each bacterial strain in Example 1 according to the proportion.

[0047] To prove that the above fermentation bacterial strain composition can specifically utilize butyric acid, and can also utilize lactic acid, acetic acid, propionic acid, and valeric acid, the above fermentation bacterial strain composition is used for aerobic fermentation in a 400 mL fermenter with a mixed organic acid (acetic acid, propionic acid, butyric acid, valeric acid, and lactic acid) as the carbon source. The fermentation medium is: adding the corresponding organic acid to Medium 2 and adjusting the pH to 7.0 ± 0.1. The proportion of different organic acids in the mixed organic acid is shown in Table 1. The inoculation amount of the fermentation bacterial strain composition is 5000 mg dry cell weight / L. The fermentation temperature is 26 °C, the pH is 7, and the dissolved oxygen is 5 - 7 mg / L.

[0048] Table 1 Composition of the mixed organic acid

[0049]

[0050]

[0051] The fermentation adopts 3 h batch fermentation, and samples are taken during the fermentation process to measure the organic acid concentration and the proportion of PHA in the cells.

[0052] The results are shown in Table 2.

[0053] Table 2 Experimental Results of Batch Fermentation of Mixed Organic Acids

[0054]

[0055] The results showed that whether in the starting stage of the first 0.5 h of fermentation or the entire fermentation process of 3 h, the consumption rate of butyric acid was relatively fast compared with other organic acids. After 3 h of fermentation, the PHA content in the cells increased from 2.54% of the cell dry weight to 49.9% of the cell dry weight, and the contribution rate of butyric acid to the PHA increment was up to 34% at most. The above results indicate that this fermentation strain composition can preferentially utilize butyric acid in the mixed organic acids for PHA synthesis, and can also utilize acetic acid, propionic acid, valeric acid and lactic acid to synthesize PHA.

[0056] Example 3 Fermentation Strain Composition and Detection of Its Utilization Efficiency of Organic Acids

[0057] This example provides a fermentation strain composition, which includes Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944 and Hydrogenophaga electricum KCTC 32195. Among them, the proportion of the cell dry weight of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944 and Hydrogenophaga electricum KCTC 32195 is 45%, 48%, 2%, 3% and 2% respectively in turn.

[0058] The above fermentation strain composition can be obtained by mixing the thalli pre-cultured from each strain in Example 1 according to the proportion.

[0059] To prove that the above fermentation strain composition can specifically utilize butyric acid and can also utilize lactic acid, acetic acid, propionic acid, and valeric acid, the above fermentation strain composition was used for aerobic fermentation in a 400 mL fermenter with a mixed organic acid (acetic acid, propionic acid, butyric acid, valeric acid, and lactic acid) as the carbon source. The fermentation medium was as follows: The corresponding organic acids were supplemented to Medium2 and the pH was adjusted to 7.0 ± 0.1. The proportion of different organic acids in the mixed organic acid was as shown in Table 1. The inoculation amount of the fermentation strain composition was 5000 mg cell dry weight / L. The fermentation temperature was 26 °C, the pH was 7, and the dissolved oxygen was 5 - 7 mg / L.

[0060] The fermentation was carried out in a 3-hour batch fermentation, and samples were taken during the fermentation process to measure the concentration of organic acids and the proportion of PHA in the cells.

[0061] The results are shown in Table 3.

[0062] Table 3 Results of batch fermentation experiment with mixed organic acids

[0063]

[0064] Example 4 Synthesis of PHA by fermentation strain composition using mixed organic acids

[0065] This example provides a method for synthesizing PHA using the fermentation strain composition of Example 2 with a mixed organic acid dominated by butyric acid, as follows:

[0066] Fermentation medium: The corresponding organic acids were supplemented to Medium2 and the pH was adjusted to 7.0 ± 0.1. The composition of the mixed organic acid (final concentration in the fermentation medium) was as shown in Table 4.

[0067] Table 4 Composition of mixed organic acid dominated by butyric acid

[0068]

[0069] Inoculation amount of the fermentation strain composition: 5000 mg cell dry weight / L.

[0070] Fermentation conditions: 400 mL aerobic fermenter, fermentation temperature 26 °C, pH 7, dissolved oxygen 5 - 7 mg / L.

[0071] Repeated batch fermentation, 1 hour for each batch, repeated 5 times.

[0072] The results showed that after 5 batches of fermentation, the PHA content in the cells increased from 10.7% of the cell dry weight to 59.62% of the cell dry weight. Among them, poly(3-hydroxybutyrate) (PHB) accounted for 52.78% of the cell dry weight, and poly(3-hydroxyvalerate) (PHV) accounted for 6.84% of the cell dry weight. By calculating the ratio of the mass of carbon in the PHA increment to the mass of carbon in the consumed organic acids, this fermentation strain composition could convert 66.79% of the carbon in the organic acids into PHA and store it in the cells. The above results indicated that this fermentation strain composition could efficiently utilize a mixed organic acid dominated by butyric acid for PHA synthesis.

[0073] Example 5: Synthesis of PHA by a Fermentation Strain Composition Using Mixed Organic Acids

[0074] This example provides a method for synthesizing PHA using the fermentation strain composition of Example 3 with a mixed organic acid dominated by butyric acid, which is as follows:

[0075] Fermentation medium: Add the corresponding organic acids to Medium2 and adjust the pH to 7.0 ± 0.1. The composition of the mixed organic acids (final concentration in the fermentation medium) is shown in Table 5.

[0076] Table 5 Composition of the Mixed Organic Acid Dominated by Butyric Acid

[0077]

[0078]

[0079] Inoculum amount of the fermentation strain composition: 5000 mg cell dry weight / L.

[0080] Fermentation conditions: 400 mL aerobic fermentation tank, fermentation temperature 26 °C, pH 7, dissolved oxygen 5 - 7 mg / L.

[0081] Repeat batch fermentation, 1 hour for each batch, repeat 5 times.

[0082] The results showed that after 5 batches of fermentation, the PHA content in the cells increased from 9.87% of the cell dry weight to 62.53% of the cell dry weight. Among them, poly(3-hydroxybutyrate) (PHB) accounted for 55.34% of the cell dry weight, and poly(3-hydroxyvalerate) (PHV) accounted for 7.19% of the cell dry weight. By calculating the ratio of the mass of carbon in the PHA increment to the mass of carbon in the consumed organic acids, this fermentation strain composition could convert 67.12% of the carbon in the organic acids into PHA and store it in the cells. The above results indicated that this fermentation strain composition could efficiently utilize a mixed organic acid dominated by butyric acid for PHA synthesis.

[0083] Comparative Example 1

[0084] This comparative example provides a fermentation bacterial strain composition, which comprises Neomegalonema perideroedes DSM 15528, Azoarcus communis DSM 12120, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195. Among them, the proportions of the dry cell weights of Neomegalonema perideroedes DSM 15528, Azoarcus communis DSM 12120, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 49.0%, 43%, 3.0%, 3.0%, and 2.0% respectively in sequence.

[0085] The above fermentation bacterial strain composition can be obtained by mixing the bacterial cells obtained through pre-cultivation in proportion, and the pre-cultivation method refers to Example 1.

[0086] Using the above fermentation bacterial strain composition, the method of Example 4 is adopted to synthesize PHA using a mixed organic acid dominated by butyric acid. The results show that after 5 batches of fermentation, the PHA content in the cells increases from 9.7% of the dry cell weight to 45.34% of the dry cell weight. Among them, poly-3-hydroxybutyrate (PHB) accounts for 39.67% of the dry cell weight, and poly-3-hydroxyvalerate (PHV) accounts for 5.67% of the dry cell weight. By calculating the ratio of the mass of carbon in the PHA increment to the mass of carbon in the consumed organic acid, this fermentation bacterial strain composition can convert 49.78% of the carbon in the organic acid into PHA and store it in the cells. It can be seen that the efficiency of this fermentation bacterial strain composition in synthesizing PHA using a mixed organic acid dominated by butyric acid is significantly lower than that of the fermentation bacterial strain composition in the example.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fermentation strain composition, characterized in that, The fermentation bacterial strain composition comprises Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM 29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195.

2. The fermentation strain composition according to claim 1, characterized in that, In the fermentation bacterial strain composition, the dry cell weight percentages of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 45 - 55%, 40 - 50%, 1 - 5%, 1 - 5%, and 1 - 3% respectively.

3. The fermentation strain composition according to claim 2, characterized in that, In the fermentation bacterial strain composition, the dry cell weight percentages of Aromatoleum Toluvorans DSM 15124, Paracoccus sanguinis DSM29303, Paracoccus aurantiacus CGMCC 1.13898, Pseudofulvimonas gallinarii DSM 21944, and Hydrogenophaga electricum KCTC 32195 are 45 - 49%, 43 - 48%, 2 - 3%, 2.5 - 3.5%, and 1.5 - 2.5% respectively.

4. Use of the fermentation strain composition according to any one of claims 1 to 3 in the production of PHA.

5. The use according to claim 4, characterized in that, The carbon source for the PHA production comprises organic acids; Preferably, the organic acid is a mixed organic acid containing butyric acid; More preferably, in the mixed organic acid, the content of butyric acid is higher than that of other organic acids.

6. The use according to claim 5, characterized in that, The mixed organic acid comprises butyric acid and one or more selected from lactic acid, acetic acid, propionic acid, and valeric acid.

7. Use of the fermentation strain composition according to any one of claims 1 to 3 in the preparation of a fermentation strain for PHA production.

8. A method for fermentatively producing PHA, characterized in that, The method includes the step of culturing the fermentation bacterial strain composition according to any one of claims 1 to 3 to obtain a culture containing PHA.

9. The method according to claim 8, characterized in that, The culturing includes fermentation culture, and the carbon source for the fermentation culture comprises organic acids; Preferably, the organic acid is a mixed organic acid containing butyric acid, and in the mixed organic acid, the content of butyric acid is higher than that of other organic acids; More preferably, the mixed organic acid comprises butyric acid and one or more selected from lactic acid, acetic acid, propionic acid, and valeric acid.

10. The method according to claim 9, characterized in that, The temperature of the fermentation culture is 25-28°C, the pH is 6.8-7.2, and the dissolved oxygen is 3-8 mg / L.

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