Method for synthesizing caproic acid by catalyzing lactic acid through microorganisms

A technology for catalyzing lactic acid and microorganisms, applied in microorganism-based methods, biochemical equipment and methods, microorganisms, etc., can solve the problems of hydrogen safety, low solubility, unfavorable caproic acid synthesis, increased extraction costs, and complex bacterial fermentation products. The effect of avoiding competition for organic substrates, increasing substrate selectivity, and improving substrate utilization

Active Publication Date: 2015-02-18
CHENGDU INST OF BIOLOGY CHINESE ACAD OF S
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Problems solved by technology

Hydrogen can also be used as an electron donor in theory, but due to the safety and low solubility of hydrogen are not conducive to the synthesis of caproic acid, and the price of hydrogen itself is relatively high, so there are few such studies; although there are a few bacteria, such as Megasphaera elsdenii T81 and Clostridium sp.BS-1 can synthesize hexanoic acid through the fermentation of glucose or galactitol, but due to the complexity of bacterial fermentation products and unknown metabolic pathways, it does not have the prospect of industrial application (Weimer P.J.&Moen G.N.Quantitative analysis of growth and volatile fatty acid production by the anaerobic ruminal bacterium Megasphaera elsdenii T81.Appl Microbiol Biotechnol.2013,97:4075–4081; Byoung Seung Jeon&Byung-Chun Kim&Youngsoon Um&Byoung-In Sang Production of hexanoic acid from D-galactitol by a newly isolated Applated BS Clost Microbiol Biotechnol.2010,88:1161–1167)
[0006] 2. The inhibitory effect of the final product makes it difficult to increase the concentration of hexanoic acid
Due to the inhibitory effect of hexanoic acid, it is difficult to continue to increase the concentration of hexanoic acid when the concentration of hexanoic acid reaches a certain level (the highest concentration reported is 12.6g / L) during the synthesis process.
This increases the extraction cost in the later stage, which is not conducive to the industrial application of microbial catalytic synthesis of hexanoic acid technology
[0007] 3. Anaerobic methanogenesis will cause substrate shunting and reduce hydrogen partial pressure, which will reduce the efficiency of caproic acid production
However, there are no relevant literature and patent reports utilizing lactic acid to synthesize hexanoic acid

Method used

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  • Method for synthesizing caproic acid by catalyzing lactic acid through microorganisms

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Experimental program
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Embodiment 1

[0035] The cultivation of embodiment 1 hexanoic acid functional flora

[0036] After the culture medium was boiled, it was divided into 250ml anaerobic bottles. Nitrogen gas was introduced until the color of the culture medium changed from blue to light red until it became colorless. It was sterilized at 121°C for 15 minutes and cooled. Inoculate caproic acid flora at a ratio of 5%. Anaerobic culture at 25-35°C for 3-5 days, the bacterial cell density OD600 reaches 3-5 bacterial suspension, and set aside.

[0037] The medium components are as follows: 1.0g lactic acid, 1g casein peptone, 0.5g yeast powder, 0.5g NH 4 Cl, 0.4g NaHCO 3 , 0.1g cysteine, 0.045g K 2 HPO 4 ,0.045g KH 2 PO 4 ,0.09g NaCl,0.009g MgSO 4 7H 2 O, 0.009g CaCl 2 , 0.1mg resazurin, 1mg hemin, 1mg biotin, 1mg vitamin B12, 3mg p-aminobenzoic acid, 5mg folic acid and 15mg vitamin B6, 100ml distilled water.

[0038] Caproic acid functional flora included Clostridium sporosphaeroides with an abundance of...

Embodiment 2

[0039] Example 2 Microbial Batch Fermentation of Lactic Acid to Produce Caproic Acid

[0040] Put the culture solution containing 50g / L lactic acid into the fermenter, sterilize at 121°C for 20 minutes, pass nitrogen gas after cooling to reduce the redox potential of the medium to below -50mV, insert 5-8% seed bacterial liquid, and pass nitrogen gas again Reduce the oxidation-reduction potential of the medium to below -50mV, control the temperature at 25-35°C, pH 5.5-5.8., stir and cultivate at 100 rpm for 10-12 days, and the hexanoic acid concentration is above 20g / L. The caproic acid fermented liquid is subjected to conventional extraction processes such as distillation and rectification to obtain high-purity food-grade caproic acid.

Embodiment 3

[0041] Example 3 Microbial continuous fermentation of lactic acid or lactic acid-containing wastewater to produce hexanoic acid and its on-line separation and purification

[0042] 1. Immobilization of microorganisms

[0043] The seed solution was transferred to an upflow anaerobic reactor containing lactic acid culture solution (attached figure 1 ), feed nitrogen / carbon dioxide (9:1) mixed gas, keep the reactor temperature at 25-35°C, make the bacteria adsorb to the immobilized film filler, until the concentration of the bacterial suspension in the reactor no longer drops;

[0044] 2. Production of caproic acid by continuous fermentation of lactic acid wastewater

[0045] (1) Pump 10g / L lactic acid (or lactic acid-containing wastewater) into the reactor, control HRT: 5d, anaerobic culture at 25-35°C, pH: 5.5-5.8, maintain the influent load of 2g lactic acid / L.d, run 10d;

[0046] (2) Control HRT: 2.5d, other conditions remain unchanged, the influent load is 4g lactic acid / ...

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Abstract

The invention relates to a method for synthesizing caproic acid by catalyzing lactic acid through microorganisms. According to the method, specific functional florae are adopted to biologically synthesize caproic acid from lactic acid in a culture liquid or wastewater. By adopting the method that lactic acid is adopted as the electron donor for producing caproic acid, the efficiency is increased by more than 20% when being compared with that of a conventional method that ethanol is adopted as an electron donor for producing caproic acid, the toxicity resistance concentration of the caproic acid functional bacterium to metabolites (caproic acid) is increased by more than 2 times when being compared with that of reported caproic acid bacteria, and the caproic acid functional bacterium has the characteristics of high conversion rate and high stress resistance. When the lactic acid as a non-fuel substance which is easy to obtain is converted into caproic acid, the conversion efficiency is high, and the high industrial practicability is achieved.

Description

technical field [0001] The invention relates to the field of environmental bioengineering and fermentation technology, in particular to a method for producing caproic acid, in particular to a method for synthesizing caproic acid by catalyzing lactic acid with microorganisms. technical background [0002] Caproic acid (n-caproate) is a medium-chain fatty acid containing six carbon atoms (C 5 h 11 COOH), with strong hydrophobicity and high energy density, is an important chemical raw material that can be directly used in the production of animal feed, green antibacterial agents and corrosion inhibitors. Its ester products are widely used in food spices, resin, rubber, pharmaceutical and other industries. In addition, caproic acid is a synthetic precursor for biofuels and can be indirectly converted to biodiesel or jet fuel through organic chemical methods. [0003] The production methods of caproic acid can be divided into chemical synthesis, extraction of natural products ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12P7/40C12R1/145
CPCC12P7/40
Inventor 陶勇朱晓宇何晓红李大平
Owner CHENGDU INST OF BIOLOGY CHINESE ACAD OF S
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