Taro Suzuki

Accumulation of poly-(hydroxybutyrate) by a non-sulfur photosynthetic bacterium, Rhodobacter sphaeroides RV at different pH

SummaryEffect of pH of culture media on intracellular accumulation of poly-(hydroxybutyrate) (PHB) by a non-sulfur photosynthetic bacterium, Rhodobacter sphaeroides strain RV was studied in pH-stat cultures. Sub-optimal pH for growth, 8.0 or 8.5 gave the higher content of PHB rather than optimal pH 7.5 for growth. These results show that growth and PHB accumulation of the bacteria can be controlled by pH of culture media.

A recombinant cyanobacterium that accumulates poly-(hydroxybutyrate)

SummaryA cyanobacterium, Synechococcus sp. PCC 7942 was transformed with a recombinant plasmid harboring poly-(hydroxybutyrate) (PHB)-synthesizing genes from Alcaligenes eutrophus. The acquired transformant accumulated about 1% PHB of dry cell weight in nitrogen-starved conditions. The PHB content of the transformant was kept stable during a series of batch cultures.

Production of poly(3-hydroxybutyrate) by photosynthetic microorganisms

Production of poly(3-hydroxybutyrate) (PHB) by photosynthetic bacteria and cyanobacteria was studied. (i)pH-stat cultures of Rhodobacter sphaeroides RV revealed that optimal pH for PHB accumulation was higher than that for growth. (ii)Some cyanobacteria including Spirulina and a thermophile accumulated PHB in about 1% of cell dry wt. Genetic engineering studies for enhancement of the productivity are going on. (iii) Rb. sphaeroides RV accumulated PHB when grown on organic compounds secreted by Spirulina platensis under dark and anaerobic conditions.