Fatty acids and their derivatives have broad application prospects in industrial fields such as energy, chemicals, and materials. Recently, the researcher of the salty desert of the bio-based chemical team of the Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences and others conducted a series of studies on the preparation of fatty acids and derivatives (fatty alcohols, hydroxy fatty acids, etc.) by biological methods. Journals such as Bioresource Technology, Applied Microbiology and Biotechnology.
Researchers focused on the key issues of low yield and poor quality of fatty acids produced by microorganisms, and conducted key technical research on the directed regulation of fatty acid quality through metabolic engineering techniques. First of all, in terms of improving the fatty acid synthesis ability, through overexpression of key enzyme genes ("tesA, ACCase, ME) in the fatty acid synthesis pathway of E. coli, fatty acid synthesis ability is enhanced, and at the same time overexpression of E. coli inner membrane invertase gene (msbA ), Improves the permeability of E. coli cell membranes, allowing free fatty acids to be secreted extracellularly; in terms of fatty acid composition and content regulation, by overexpressing E. coli's own unsaturated fatty acid synthesis genes fabA and fabB and from Arabidopsis thaliana For desaturase ssi2 / fab2, the content of unsaturated fatty acids increased from 49.8% to 69.7%, and the ratio of unsaturated fatty acids to saturated fatty acids increased from 1: 1 to 2.3: 1. Related achievements have been published in 2 SCI articles (Appl. Microbiol. Biotechnol, 2010, 87: 271-280, Protein Expression and Purification, 2010, 69: 209C214), applied for 2 patents (CN101899468A; 201010273824.8).
In order to further increase the content of extracellular fatty acids, according to the information obtained from the above research, through the optimization of fermentation conditions, including the addition of organic nitrogen sources in the culture medium, the selection of secondary temperature-variable fermentation process, combined with online extraction process and other technologies, significantly increased fatty acids Yield and product concentration. The results show that in a 5-liter fermentation system, the total lipid production can reach 10.6 g / L, the total yield is 6.1%, the extracellular fatty acid production in the fermentation broth can reach 5.1 g / L, and the intracellular and extracellular fatty acid ratio can be reduced to 0.7, which is far higher The ratio has been reported. Related research results published 1 SCI paper (Microbial Cell Factories 2012, 11:41).
Hydroxy fatty acid is an important chemical raw material, widely used in chemical, biological, food and green polymer materials and other industries. Based on the preliminary research on fatty acids, the team conducted a study on the biological method of preparing hydroxy fatty acids. Through the combined expression analysis of multiple exogenous genes, a hydroxy fatty acid production strain with glucose as a substrate was selected. The yield of hydroxy fatty acid reached 123.6 mg / L under shake flask fermentation conditions. In addition, an engineering strain for conversion reaction with exogenous fatty acid as substrate was constructed. When this strain used 2.5 mM lauric acid as the substrate, the conversion rate of lauric acid was 96.2%, and the yield of hydroxylauric acid was 529.0 mg / L. Related results were published in (Bioresource Technology, 2012, 114: 561-566). This research provides a solid theoretical basis for the future preparation of hydroxy fatty acids by biological methods.
Fatty alcohol is a basic chemical raw material for the synthesis of surfactants, detergents, plasticizers and other fine chemicals. It is widely used in textile, daily chemical, paper, food, medicine, leather and other fields. The research group has conducted relevant research on the preparation of fatty alcohols by biological methods using metabolic engineering technology. The results prove that: by optimizing the gene expression pattern of key enzymes, C12 / 14 carbon fatty alcohols and C16 / 18 fatty alcohols can be selectively synthesized. The results of the study found that engineering strain Zh072 can obtain 449.2 mg / L C12 / 14 fatty alcohol by fermentation, and its content accounts for 75% of the total fatty alcohol (598.6 mg / L); while engineering Zh054 can obtain 101.5 mg / L C16 / by fermentation 18 fatty alcohol, its content accounts for 89.2% of the total fatty alcohol. Relevant achievements Published 1 SCI paper (Microbial Cell Factories 2012, 11: 65), 1 authorized patent (patent number: ZL 200910090469.8).
The above research provides new scientific clues for the high quality and low cost of fatty acids.
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