title: Methyl-branched poly(hydroxyalkanoate) biosynthesis from 13-methyltetradecanoic acid and mixed isostearic acid isomer substrates.
abstract: Pseudomonas resinovorans, a known medium-chain-length (mcl-) poly(hydroxyalkanoate) (PHA) producer, was grown on 13-methyltetradecanoic acid (13-MTDA) and a mixture of isostearic acid (IA) isomers to produce methyl-branched mcl-PHA polymers. Shake-flask experiments revealed polymer productivities (the percent of the cell mass that is polymer) of 31 +/- 1% (n = 3) and 23 +/- 3% (n = 3) when grown in 13-MTDA and IA, respectively. Monomer content was determined by a combination of gas chromatography/mass spectrometry (GC/MS) of the acid hydrolyzed, silylated methyl esters, and nuclear magnetic resonance spectroscopy. Results showed that the mcl-PHA polymer derived from 13-MTDA was primarily composed of 3-hydroxy-7-methyloctanoic acid and 3-hydroxy-9-methyldecanoic acid (67 and 16 mol% by GC/MS, respectively). In contrast, the mcl-polymers synthesized from the IA isomeric mixture were more complex, containing both even and odd chain-length monomers as well as varying distributions of methyl-branched derivatives. The PHA distributions among the C8, C10, C12, and C14 carbon chain-length monomers included three isomers of C8, five isomers of C10, seven isomers of C12, and nine isomers of C14 each containing one linear-chain derivative and n-6 methyl-branched derivatives where n equals the total number of carbon atoms in each monomer unit (C8-C14).
authors: Fats, Oils and Animal Coproducts Research Unit, US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA. Rick.Ashby@ars.usda.gov
authors: Richard D
authors: RD
authors: Ashby
authors: Helen L
authors: HL
authors: Ngo
authors: Daniel K Y
authors: DK
authors: Solaiman
authors: Gary
authors: G
authors: Strahan
mesh_terms: D001419:Bacteria / Q000378:metabolism; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D019814:Myristic Acid / Q000378:metabolism*; D009227:Myristic Acids / Q000378:metabolism; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis* / Q000737:chemistry; D011549:Pseudomonas / Q000378:metabolism*; D013229:Stearic Acids / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D009227:Myristic Acids; D054813:Polyhydroxyalkanoates; D013229:Stearic Acids; D019814:Myristic Acid; C040995:isostearic acid