ARS | Publication request: Selective microbial degradation of saturated methyl branched chain fatty acid isomers

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 16, 2012
Publication Date: June 14, 2012
Citation: Ngo, H., Ashby, R.D., Nunez, A. 2012. Selective microbial degradation of saturated methyl branched chain fatty acid isomers. Journal of the American Oil Chemists' Society. DOI: 10.1007/s11746-012-2092-0 89:1885-1893.

Interpretive Summary: Environmental concerns have dictated a shift in focus to the development of biobased materials from renewable resources. Biobased materials do not leach harmful chemicals into the environment as they degrade. Currently, most lubricants are petroleum-based and derived from crude oil. Switching to the use of biobased lubricants would not only lessen our dependence on foreign oil but would also place less burden on the environment. Saturated branched-chain fatty acid products (sbc-FAs) are found to have potential applications as lubricants. Sbc-FAs are made from renewable materials. The objective of this work was to determine if sbc-FA products are biodegradable in order to gain a better understanding of the potential impact of sbc-FAs upon disposal. Three strains of Pseudomonas bacteria were screened for their capabilities of degrading sbc-FAs. The results showed that sbc-FAs are biodegradable under the conditions employed. The demonstrated biodegradable nature of these sbc-FAs paves the way for their adoption in “environmentally friendly” applications.

Technical Abstract: Three strains of Pseudomonas bacteria were screened for their capabilities of degrading chemically synthesized saturated branched-chain fatty acids (sbc-FAs). Mixtures of sbc-FAs 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-FAs was monitored based on positive bacterial growth, fatty acid recovery rates and chromatographic (GC and GC-MS) analysis of the recovered carbon source. Pseudomonas (P.) putida KT2442 and P. oleovorans NRRL B-14683 were both able to grow on sbc-FAs utilizing 35% and 27% 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 short chain fatty acids (approximately 4 to 29%) were formed during degradation.