Biosynthesis of poly‐3‐hydroxybutyric acid by the facultatively methanol‐assimilating bacterium Mycoplana rubra B346 and recombinant strains

Mycoplana rubra B346 is a pink‐pigmented facultatively methylotrophic bacterium which is capable of synthesizing and accumulating small amounts of poly‐3‐hydroxybutyric acid (PHB) if a carbon source (e.g. methanol) is provided in excess and if an essential nutrient (e.g. nitrogen or phoshorus, respectively) is limiting growth. Upon transfer of the PHA‐biosynthesis genes of Alcaligenes eutrophus H16 or Chromatium vinosum D or of the isolated PHA‐synthase structural gene of Methylobacterium extorquens into M. rubra B346, the content of PHB increased from 9.6 up to 25% of the cell dry matter. M. rubra and some recombinant strains were characterized physiologically and morphologically, and the size of the cells and the PHB content were compared by flow cytometry.