Fed-batch production of unsaturated medium-chain-length polyhydroxyalkanoates with controlled composition by Pseudomonas putida KT2440.
Unsaturated medium-chain-length polyhydroxyalkanoates (MCL-PHA) were produced at a productivity of 0.63-1.09 g PHA l(-1) h(-1) with final PHA content ranging from 42.6 to 55.8% in single-stage, carbon-limited, fed-batch fermentations of Pseudomonas putida KT2440. A mixture of nonanoic acid (NA) and 10-undecenoic acid (UDA=) was fed exponentially to control growth rate. Varying the specific growth rate (0.14 h(-1) vs. 0.23 h(-1)) at similar substrate feed ratios (NA:UDA= = 5:1) had little effect on the final PHA content and relative composition. However, decreasing the NA:UDA= ratio decreased the final amount of PHA produced from 56% with NA:UDA= = 5.07:1 to only 42% at NA:UDA= = 2.47:1. The molar fraction of all 3-hydroxyalkanoate monomers in the PHA product was relatively constant throughout each fermentation, indicating that the final product was homogeneous rather than a mixture of different copolymers. A linear relationship between unsaturation of the PHA produced and unsaturation of the carbon feed was found, which demonstrates the feasibility of producing unsaturated MCL-PHAs with controlled polymeric composition in a fed-batch process.
Sun
Zhiyong
Z
Chemical Engineering, Queen's University, Kingston, Ontario, Canada.
Ramsay
Juliana A
JA
Guay
Martin
M
Ramsay
Bruce A
BA
D019149:Bioreactors / Q000382:microbiology*; D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D005285:Fermentation; D007700:Kinetics; D054813:Polyhydroxyalkanoates / Q000737:chemistry / Q000378:metabolism*; D016958:Pseudomonas putida / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*
D003470:Culture Media; D054813:Polyhydroxyalkanoates