title: Biosynthesis of novel polyhydroxyalkanoate containing 3-hydroxy-4-methylvalerate by Chromobacterium sp. USM2.
abstract: OBJECTIVE
  Polyhydroxyalkanoate (PHA) with enhanced physicochemical properties will be ideal for a wide range of practical applications. The incorporation of 3-hydroxy-4-methylvalerate (3H4MV) into the polymer backbone is known to improve the overall properties of the resulting polymer. However, the most suitable micro-organism and PHA synthase that can synthesize this monomer efficiently still remain unknown at present. Therefore, we evaluated the abilities of a locally isolated Chromobacterium sp. USM2 to produce PHA containing 3H4MV.
  
  
  RESULTS
  The ability of Chromobacterium sp. USM2 to synthesize poly(3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate) [P(3HB-co-3H4MV)] was evaluated under different culture conditions. It was found that Chromobacterium sp. USM2 can synthesize P(3HB-co-3H4MV) when glucose and isocaproic acid were fed as carbon source. However, the highest molar fraction of 3H4MV, 22 mol% was detected in Chromobacterium sp. USM2 when isocaproic acid was provided as the sole carbon source. In addition, aeration was identified as a crucial factor in initiating the accumulation of high 3H4MV molar fractions.
  
  
  CONCLUSIONS
  Chromobacterium sp. USM2 was able to synthesize broad comonomer compositional distribution of P(3HB-co-3H4MV).
  
  
  CONCLUSIONS
  Compared with Cupriavidus necator and Burkholderia sp., Chromobacterium sp. USM2 was found to have better ability to bioconvert isocaproic acid to form 3H4MV unit.
authors.affiliation: Ecobiomaterial Research Laboratory, School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia.
authors.forename: S C
authors.initials: SC
authors.lastname: Ling
authors.forename: T
authors.initials: T
authors.lastname: Tsuge
authors.forename: K
authors.initials: K
authors.lastname: Sudesh
mesh_terms: D000217:Acyltransferases / Q000378:metabolism; D002208:Caproates / Q000378:metabolism; D002861:Chromobacterium / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010802:Phylogeny; D011091:Polyesters / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis*; D017386:Sequence Homology, Amino Acid; D000094122:Polyhydroxybutyrates
chemical_list: D000217:Acyltransferases; D002208:Caproates; D003470:Culture Media; D005947:Glucose; D011091:Polyesters; D054813:Polyhydroxyalkanoates; C553274:poly(3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate); D000094122:Polyhydroxybutyrates; C034527:isocaproic acid; C077225:poly(3-hydroxyalkanoic acid) synthase