Some strains of Pseudomonas corrugata (Pco) and P. mediterranea (Pme) efficiently synthesize medium-chain-length polyhydroxyalkanoates elastomers (mcl-PHA) and extracellular products on related and unrelated carbon sources. Yield and composition are dependent on the strain, carbon source, fermentation process, and any additives. Selected Pco strains produce amorphous and sticky mcl-PHA, whereas strains of Pme produce, on high grade and partially refined biodiesel glycerol, a distinctive filmable PHA, very different from the conventional microbial mcl-PHA, suitable for making blends with polylactide acid. However, the yields still need to be improved and production costs lowered. An integrated process has been developed to recover intracellular mcl-PHA and extracellular bioactive molecules. Transcriptional regulation studies during PHA production contribute to understanding the metabolic potential of Pco and Pme strains. Data available suggest that pha biosynthesis genes and their regulations will be helpful to develop new, integrated strategies for cost-effective production.
Keywords: Pseudomonas; alginate; biopolymer; biosurfactants; blends; film; medium-chain-length polyhydroxyalkanoate (mcl-PHA).