One-step biosynthesis of ?-ketoisocaproate from L-leucine by an Escherichia coli whole-cell biocatalyst expressing an L-amino acid deaminase from Proteus vulgaris.

ABSTRACT: This work aimed to develop a whole-cell biotransformation process for the production of ?-ketoisocaproate from L-leucine. A recombinant Escherichia coli strain was constructed by expressing an L-amino acid deaminase from Proteus vulgaris. To enhance ?-ketoisocaproate production, the reaction conditions were optimized as follows: whole-cell biocatalyst 0.8?g/L, leucine concentration 13.1?g/L, temperature 35?°C, pH 7.5, and reaction time 20?h. Under the above conditions, the ?-ketoisocaproate titer reached 12.7?g/L with a leucine conversion rate of 97.8%. In addition, different leucine feeding strategies were examined to increase the ?-ketoisocaproate titer. When 13.1?g/L leucine was added at 2-h intervals (from 0 to 22?h, 12 addition times), the ?-ketoisocaproate titer reached 69.1?g/L, while the leucine conversion rate decreased to 50.3%. We have developed an effective process for the biotechnological production of ?-ketoisocaproate that is more environmentally friendly than the traditional petrochemical synthesis approach.

SUBMITTER: Song Y 

PROVIDER: S-EPMC4517468 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature