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

摘要

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(C8+C10)/G was only 0.057 mol mol(-1) during PHA synthesis from glucose. When nonanoic acid and glucose were fed together, Y(C7+C8)/NA almost doubled to 0.450 mol mol(-1) while Y(C8+C10)/G 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.