The synthesis of short- and medium-chain-length poly(hydroxyalkanoate) mixtures from glucose- or alkanoic acid-grown Pseudomonas oleovorans.
Pseudomonas oleovorans NRRL B-778 accumulated mixtures of poly-3-hydroxybutyrate (PHB) and medium-chain-length poly(hydroxyalkanoates) (mcl-PHAs) when grown on glucose, octanoic acid or oleic acid, whereas growth on nonanoic acid or undecanoic acid resulted in copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-co-HV). Acetone fractionation verified the presence of PHB/mcl-PHA mixtures. The acetone-insoluble (AIS) fractions of the polymers derived from glucose (PHA-glucose), octanoic acid (PHA-octanoic) and oleic acid (PHA-oleic) were exclusively PHB while the acetone-soluble (AS) fractions contained mcl-PHA composed of differing ratios of 3-hydroxy-acid monomer units, which ranged in chain length from 6 to 14 carbon atoms. In contrast, both the AIS and AS fractions from the polymers derived from nonanoic acid (PHA-nonanoic) and undecanoic acid (PHA-undecanoic) were composed of comparable ratios of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). The unfractionated PHA-glucose, PHA-octanoic and PHA-oleic polymers had melting temperatures (Tm) between 177 and 179 degrees C, enthalpies of fusion (AHf) of 20 cal/g and glasstransition temperatures (Tg) of 3-4 degrees C. This was due to the large PHB content in the polymer mixtures. On the other hand, the PHA-nonanoic and PHA-undecanoic polymers had thermal properties that supported their copolymer nature. In both cases, the Tm values were 161 degrees C, deltaHf values were 7 cal/g and Tg values were - 3 degrees C.
Ashby
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RD
Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, Wyndmoor, PA 19038, USA.
Solaiman
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DK
Foglia
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TA
D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000378:metabolism*; D006880:Hydroxy Acids / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000378:metabolism; D010084:Oxidation-Reduction; D010421:Pentanoic Acids / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism; D011108:Polymers / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
D005947:Glucose; D006880:Hydroxy Acids; D006885:Hydroxybutyrates; D010421:Pentanoic Acids; D011091:Polyesters; D011108:Polymers; C013056:beta-hydroxyvaleric acid; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates