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CN-121975874-A - Method for directionally producing odd-carbon medium-chain fatty acid by using brewing wastewater

CN121975874ACN 121975874 ACN121975874 ACN 121975874ACN-121975874-A

Abstract

The invention discloses a method for directionally producing odd-carbon medium-chain fatty acid by utilizing brewing wastewater, belonging to the field of biotechnology and waste recycling. The method comprises the steps of supplementing nutritional components into brewing wastewater to prepare a fermentation substrate, inoculating domesticated functional flora, and fermenting under anaerobic conditions, wherein the pH value of a system is maintained to be 5.5-5.8 by adding propionic acid. Propionic acid is used as a pH regulator and a supplementary substrate to cooperatively promote metabolism, so that a carbon source in the wastewater is efficiently and directionally converted into odd-carbon medium-chain fatty acid mainly comprising valeric acid and heptanoic acid. The method realizes the recycling and high-value utilization of the brewing wastewater and has the advantages of green process, simple and convenient operation and strong product directionality.

Inventors

  • WANG HAN
  • ZHAO DONG
  • LIU LI
  • CHEN SHIJIANG
  • YUAN CHUNFANG
  • GOU ZIXI
  • LI QIJUN
  • LIU YAO
  • SU JIAN
  • ZHENG JIA

Assignees

  • 宜宾五粮液股份有限公司

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. A method for directionally producing odd-carbon medium-chain fatty acid by using brewing wastewater, which is characterized by comprising the following steps: S1, preparing a fermentation substrate, namely adding a trace element concentrated solution, a vitamin concentrated solution and an L-cysteine solution into brewing wastewater, and uniformly mixing to prepare the fermentation substrate; Wherein the fermentation substrate contains 26-89 g/L of lactic acid, 5-25 g/L, L-0.25 g/L of glucose and effective amounts of trace elements and vitamins; s2, directional anaerobic fermentation, namely inoculating functional flora capable of synthesizing odd-carbon medium-chain fatty acid by using a fermentation matrix by taking the fermentation matrix as a substrate, and fermenting under anaerobic conditions; And adding propionic acid into a fermentation system in the fermentation process, maintaining the pH of the system at 5.5-5.8, controlling the residence time of materials in the system at 6-12 d and the fermentation temperature at 30-35 ℃ to obtain fermentation liquor containing odd-carbon medium-chain fatty acid.
  2. 2. The method for directionally producing odd-numbered medium-chain fatty acids by utilizing brewing wastewater according to claim 1, wherein in the step S1, the brewing wastewater contains 26-89 g/L of lactic acid and 5-25 g/L of glucose.
  3. 3. The method for directionally producing odd-numbered carbon medium-chain fatty acids by utilizing brewing wastewater according to claim 1, wherein in the step S1, the adding amount of the trace element concentrated solution is 50-100 mL/L of the brewing wastewater; each liter of the trace element concentrated solution contains ：NaCl 11.7g、NH 4 Cl 2.37g、CaCl 2 ·2H 2 O 0.65g、MgCl 2 ·6H 2 O 0.25g、MnCl 2 ·4H 2 O 0.31g、ZnCl 2 ·H 2 O 0.12g、CoCl 2 ·6H 2 O 0.048g, parts of water.
  4. 4. The method for directionally producing odd-numbered medium-chain fatty acids by utilizing brewing wastewater according to claim 1, wherein in the step S1, the addition amount of the vitamin concentrate is 3-5 mL/L of the brewing wastewater; The vitamin concentrate contains 20mg of pyridoxine hydrochloride, 10mg of thiamine, 10mg of riboflavin, 10mg of calcium pantothenate, 10mg of lipoic acid, 10mg of para-aminobenzoic acid, 10mg of nicotinic acid, 12 mg of vitamin B, 20mg of biotin, 4mg of folic acid, 4mg of sodium 2-mercaptoethane sulfonate and the balance of water per liter.
  5. 5. The method for directionally producing odd-numbered medium-chain fatty acids by utilizing brewing wastewater according to claim 1, wherein in the step S2, the inoculation amount of the functional flora is 2-10% (v/v) of the fermentation substrate; The functional flora includes at least one of microorganisms of the genus Caproicibacterium, caproicibacter, thermocaproicibacter, and Caproiciproducens.
  6. 6. The method for the directional production of odd-numbered medium-chain fatty acids by means of brewery wastewater according to claim 1, wherein in step S2, said functional flora is obtained by the following domestication method: a. taking pit mud as a bacterial source, and mixing 1-5 g pit mud with 10-50 mL sterile oxygen-free water to prepare bacterial suspension; b. Preparing a liquid culture medium, and introducing nitrogen into the liquid culture medium to perform aeration for 12-20 min to obtain an anaerobic culture medium for later use; c. Inoculating the bacterial suspension into an anaerobic culture medium according to an inoculum size of 2% (v/v), culturing for 5-7 d under anaerobic conditions with a pH value of 4.0-7.0 and a temperature of 20-50 ℃, and performing multiple rounds of passage domestication and enrichment culture to obtain functional bacterial groups capable of synthesizing medium-chain fatty acid by utilizing brewing wastewater.
  7. 7. The method for directionally producing odd-numbered medium-chain fatty acids by utilizing brewing wastewater according to claim 6, wherein in the step b, the liquid culture medium consists of 126-425 ml of brewing wastewater, 0.1-0.25 g of L-cysteine, 50-100 ml of microelement concentrate, 3-5 ml of vitamin concentrate and the balance of distilled water; wherein the brewing wastewater contains 26-89 g/L of lactic acid and 5-25 g/L of glucose; each liter of the trace element concentrated solution contains ：NaCl 11.7g、NH 4 Cl 2.37g、CaCl 2 ·2H 2 O 0.65g、MgCl 2 ·6H 2 O 0.25g、MnCl 2 ·4H 2 O 0.31g、ZnCl 2 ·H 2 O 0.12g、CoCl 2 ·6H 2 O 0.048g, parts of distilled water; the vitamin concentrate contains 20mg of pyridoxine hydrochloride, 10mg of thiamine, 10mg of riboflavin, 10mg of calcium pantothenate, 10mg of lipoic acid, 10mg of para-aminobenzoic acid, 10mg of nicotinic acid, 12 mg of vitamin B, 20mg of biotin, 4mg of folic acid, 4mg of sodium 2-mercaptoethane sulfonate and the balance of distilled water per liter.
  8. 8. The method for the directional production of odd-numbered medium-chain fatty acids by using brewing wastewater according to claim 1, wherein in step S2, the anaerobic fermentation is performed in a membrane filtration anaerobic bioreactor.
  9. 9. The method for directionally producing odd-numbered medium-chain fatty acids by utilizing brewing wastewater according to claim 1, wherein in the step S2, inorganic acid is used for adjusting the pH value of a system to 5.5-5.8 in a fermentation starting stage, after the system is stable in operation, propionic acid is added to maintain the pH value range, and the concentration of the propionic acid is 0.05-0.1 mol/L.
  10. 10. The method for the directional production of odd-numbered medium-chain fatty acids by using brewing wastewater according to claim 1, wherein in the step S2, the odd-numbered medium-chain fatty acids comprise at least one of valeric acid and heptanoic acid.

Description

Method for directionally producing odd-carbon medium-chain fatty acid by using brewing wastewater Technical Field The invention belongs to the field of biotechnology and waste recycling, relates to a method for producing high-value chemicals by anaerobic fermentation of brewing wastewater, and in particular relates to a method for directionally producing odd-carbon medium-chain fatty acid by utilizing the brewing wastewater. Background The microbial carbon chain extension technology is utilized to convert the waste biomass rich in organic matters into medium-chain fatty acid, which is an important direction for realizing the recycling and high-value utilization of the waste. The energy density and the added value of the medium-chain fatty acid are higher than those of the short-chain fatty acid, and the application prospect in the fields of chemical industry, energy, medicine and the like is wide. However, this technique is highly dependent on precise control of the fermentation microenvironment, such as pH, being one of the most critical parameters affecting microbial growth metabolism, enzyme activity and product selectivity. In order to maintain the optimal reaction environment, the traditional process is mostly regulated by adding strong acid and strong alkali. For example, CN118956982a discloses a method for enhancing medium chain fatty acid biosynthesis by double effect composite electroactive materials, which controls pH by adding high concentration hydrochloric acid or sodium hydroxide during fermentation. This approach, while intuitive, introduces additional cost of chemicals and inorganic salt ions. Accumulation of these exogenous ions can be toxic to the microbial community, interfere with its metabolic functions, and increase the complexity and cost of downstream product separation. In order to improve the continuity and stability of the process, the prior art has also explored more complex regulatory strategies. For example, CN120758576B discloses a continuous synthesis method of medium chain fatty acid, which utilizes acidic or basic substances generated by fermentation reaction itself to dynamically stabilize pH by precisely controlling substrate flow rate and hydraulic retention time. However, the implementation of the scheme depends on a complex multistage reactor and an online monitoring and real-time feedback control system, and the method has the advantages of complex process flow, high equipment investment, high operation stability requirement and difficult large-scale popularization. In addition, in the aspect of raw materials, the components of many wastes (such as kitchen waste and agricultural straw) are complex, the pretreatment cost is high, and relatively clear high-concentration organic wastewater (such as brewing wastewater) has more utilization potential, but the adaptability of specific components to functional microorganisms is particularly required. Furthermore, at the product level, MCFAs products synthesized by the prior art are generally limited in spectrum, mainly concentrated in even-numbered fatty acids such as butyric acid, caproic acid, etc., poor in selectivity to odd-numbered fatty acids, and generally low in yield. Therefore, a method for efficiently utilizing specific waste biomass resources, realizing stable process regulation and control on the premise of avoiding secondary pollution and control cost, and directionally synthesizing high-value medium-chain fatty acid is needed. Disclosure of Invention The invention aims to solve the technical problems that the method for adjusting the pH in the traditional microbial fermentation technology has high technical cost and is easy to destroy microbial ecology. In order to achieve the purposes of the application, the technical scheme adopted by the application is as follows. The invention provides a method for directionally producing odd-numbered carbon medium-chain fatty acid by utilizing brewing wastewater, which comprises the following steps: S1, preparing a fermentation substrate, namely adding a trace element concentrated solution, a vitamin concentrated solution and an L-cysteine solution into brewing wastewater, and uniformly mixing to prepare the fermentation substrate; Wherein the fermentation substrate contains 26-89 g/L of lactic acid, 5-25 g/L, L-0.25 g/L of glucose and effective amounts of trace elements and vitamins; s2, directional anaerobic fermentation, namely inoculating functional flora capable of synthesizing odd-carbon medium-chain fatty acid by using a fermentation matrix by taking the fermentation matrix as a substrate, and fermenting under anaerobic conditions; And adding propionic acid into a fermentation system in the fermentation process, maintaining the pH of the system at 5.5-5.8, controlling the residence time of materials in the system at 6-12 d and the fermentation temperature at 30-35 ℃ to obtain fermentation liquor containing odd-carbon medium-chain fatty acid. In the step S1, the bre