Selective Microbial Degradation of Saturated Methyl Branched-Chain Fatty Acid Isomers

摘要

Three strains of Pseudomonas (P.) bacteria were screened for their capabilities of degrading chemically synthesized saturated branched-chain fatty acids (sbc–FA). Mixtures of sbc–FA with the methyl-branch located at various locales along the fatty acid were used as a carbon feedstock in shake-flask culture. Utilization (and hence degradability) of the sbc–FA was monitored based on positive bacterial growth, fatty acid recovery rates and chromatographic (gas chromatography (GC) and GC-mass spectroscopy (MS)) analysis of the recovered carbon source. P. putida KT2442 and P. oleovorans NRRL B-14683 were both able to grow on sbc–FA utilizing 35 wt% and 27 wt% of the carbon source, respectively after 144 h. In contrast, P. resinovorans NRRL B-2649 exhibited the most efficient use of the carbon source by utilizing 89 % of the starting material after 96 h resulting in a cell dry weight (CDW) of 3.1 g/L. GC and GC–MS analysis of the recovered carbon source revealed that the bacterial strains selectively utilized the isostearic acid in the sbc–FA mixture, and a new group of C10, C12, C14 and C16-linear and/or branched-chain fatty acids (approximately 4–29 wt%) were formed during degradation.