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Biosynthesis and characterization of 3‐hydroxyalkanoate terpolyesters with adjustable properties by Aeromonas hydrophila
Author(s) -
Zhang HaiFeng,
Ma Long,
Wang ZhiHui,
Chen GuoQiang
Publication year - 2009
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.22409
Subject(s) - aeromonas hydrophila , chemistry , polyhydroxyalkanoates , thermostability , monomer , nuclear chemistry , recombinant dna , biosynthesis , biochemistry , bacteria , lauric acid , enzyme , gene , organic chemistry , biology , genetics , fatty acid , polymer
Polyhydroxyalkanoates (PHA) terployesters P(3HB‐ co ‐3HV‐ co ‐3HHx) consisting of 3‐hydroxybutyrate (3HB), 3‐hydroxyvalerate (3HV), and 3‐hydroxyhexanoate (3HHx) were produced by wild‐type Aeromonas hydrophila 4AK4, its recombinant harboring PHA synthesis genes phaPCJ encoding PHA binding protein phasin, PHA synthase, and enoyl‐CoA hydratase, and another its recombinant harboring phaAB encoding beta‐ketothiolase and acetoacetyl‐CoA reductase, respectively, when grown in lauric acid and/or valerate. The terpolyesters produced by A. hydrophila 4AK4 ( phaAB ) grown in velarate were found to produce copolymers P(3HB‐ co ‐3HV) containing high 3HV fractions with a maximum of 99 mol% 3HV. In terpolyesters, 3HV ranged from 9 to 32 mol% depending on the valerate concentration and strain used. A maximal terpolyester P(3HB‐ co ‐3HV‐ co ‐3HHx) content in dry cells was 71 wt%. Transmission electron microscopy study of A. hydrophila 4AK4 harboring phaPCJ revealed the full occupation of terpolyester P(3HB‐ co ‐3HV‐ co ‐HHx) in the cellular spaces. Terpolyesters with various monomer compositions showed changing thermal and mechanical properties. Those with higher 3HV fractions demonstrated an improved property over the lower HV containing ones. Biotechnol. Bioeng. 2009; 104: 582–589 © 2009 Wiley Periodicals, Inc.