Polyhydroxyalkanoate (PHA) Biosynthesis from Whey Lactose

Abstract

AbstractSummary: The potential of three different microbial wild type strains as polyhydroxyalkanoate (PHA) producers from whey lactose is compared. Homopolyester and co‐polyester biosynthesis was investigated by the archaeon Haloferax mediterranei and the eubacterial strains Pseudomonas hydrogenovora and Hydrogenophaga pseudoflava. H. mediterranei accumulated 50 wt.‐% of poly‐3‐(hydroxybutyrate‐co‐6%‐hydroxyvalerate) in cell dry mass from hydrolyzed whey without addition of 3‐hydroxyvalerate (3HV) precursors (specific productivity qp: 2.9 mg/g h). Using P. hydrogenovora, the final percentage of poly‐3‐hydroxybutyrate (PHB) amounted to 12 wt.‐% (qp: 0.03 g/g h); co‐feeding of valeric acid resulted in the production of 12 wt.‐%. P‐3(HB‐co‐21%‐HV) (qp: 0.02 g/g h). With H. pseudoflava, it was possible to reach 40 wt.‐% P‐3 (HB‐co‐5%‐HV) on not‐hydrolyzed whey lactose plus valeric acid as 3HV precursor (qp: 9.1 mg/g h); on hydrolyzed whey lactose without addition of valeric acid, the strain produced 30 wt.‐% of PHB (qp: 0.16 g/g h). The characterization of the isolated biopolyesters completes the study.