Increasing the yield of MCL-PHA from nonanoic acid by co-feeding glucose during the PHA accumulation stage in two-stage fed-batch fermentations of Pseudomonas putida KT2440

A method was developed to increase the yield of MCL-PHA from nonanoic acid in the PHA accumulation phase. Pseudomonas putida KT2440 was grown on glucose until ammonium-limitation was imposed. In the second (accumulation) stage, either glucose, nonanoic acid, or a mixture of these carbon and energy sources was supplied. Since the medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA) subunits produced are unique for each carbon source, their relative contribution to PHA yield could be calculated. Y(C7+C9)/NA was 0.254 mol mol(-1) during PHA synthesis from nonanoic, acid. Y(C7+C9)/NA was only 0.057 mol mol(-1) during PHA synthesis from glucose. When nonanoic acid and glucose were fed together, Y(C7+C9)/NA almost doubled to 0.450 mol mol(-1) while Y(C7+C9)/NA decreased to 0.011 mol mol(-1). These results demonstrate that substantial savings can be obtained by feeding glucose with substrates that are good for PHA production but much more expensive than glucose. (c) 2007 Elsevier B.V. All rights reserved.