Hydrolase BioH knockout in E. coli enables efficient fatty acid methyl ester bioprocessing

• Published in: Journal of industrial microbiology & biotechnology Vol. 44; no. 3; pp. 339 - 351
• Main Authors: Kadisch, Marvin, Schmid, Andreas, Bühler, Bruno
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Oxford University Press 01.03.2017; Springer Berlin Heidelberg
• Subjects: alkanes; biocatalysis; Biocatalysis - Original Paper; Biochemistry; Biodiesel fuels; Biofuels; Bioinformatics; Biomedical and Life Sciences; bioprocessing; Bioreactors; Biotechnology; Biotin; Biotransformation; Catalysis; Chemicals; E coli; Enzymes; Escherichia coli; Escherichia coli - enzymology; Escherichia coli K12; Esters; Esters - metabolism; fatty acid methyl esters; Fatty acids; Fatty Acids - metabolism; feedstocks; free fatty acids; Gene expression; Gene Knockout Techniques; Genetic Engineering; Glucose; Hydrolases - genetics; Hydrolases - metabolism; Hydrolysis; Industrial Microbiology; Inorganic Chemistry; Life Sciences; Metabolic Engineering; Metabolism; Microbiology; Microorganisms; Oxidation; plant fats and oils; Plasmids; Polymers; Fatty acid methyl ester hydrolysis; Metabolic engineering; Industrial biotechnology; Whole-cell biocatalysis; BioH
• ISSN: 1367-5435; 1476-5535; 1476-5535
• DOI: 10.1007/s10295-016-1890-z

Abstract Fatty acid methyl esters (FAMEs) originating from plant oils are most interesting renewable feedstocks for biofuels and bio-based materials. FAMEs can also be produced and/or functionalized by engineered microbes to give access to, e.g., polymer building blocks. Yet, they are often subject to hydrolysis yielding free fatty acids, which typically are degraded by microbes. We identified BioH as the key enzyme responsible for the hydrolysis of medium-chain length FAME derivatives in different E. coli K-12 strains. E. coli ΔbioH strains showed up to 22-fold reduced FAME hydrolysis rates in comparison with respective wild-type strains. Knockout strains showed, beside the expected biotin auxotrophy, unchanged growth behavior and biocatalytic activity. Thus, high specific rates (~80 U gCDW −1) for terminal FAME oxyfunctionalization catalyzed by a recombinant alkane monooxygenase could be combined with reduced hydrolysis. Biotransformations in process-relevant two-liquid phase systems profited from reduced fatty acid accumulation and/or reduced substrate loss via free fatty acid metabolization. The BioH knockout strategy was beneficial in all tested strains, although its effect was found to differ according to specific strain properties, such as FAME hydrolysis and FFA degradation activities. BioH or functional analogs can be found in virtually all microorganisms, making bioH deletion a broadly applicable strategy for efficient microbial bioprocessing involving FAMEs.