Accumulation of poly-β-hydroxybutyrate by Rhodobacter sphaeroides on various carbon and nitrogen substrates

Combinations of various carbon and nitrogen substrates were used to study poly-beta-hydroxybutyrate accumulation and H-2 evolution by Rhodobacter sphaeroides strain RV. The cells evolved hydrogen on lactate, pyruvate, or succinate under nitrogen-deprived conditions and on lactate-glutamate and pyruvate-glutamate media. Poly-beta-hydroxybutyrate content under nitrogen-sufficient and nitrogen-deprived conditions was highest on acetate (up to similar to 40% of cell dry weight). Transfer of the cells from ammonium to ammonium-free medium resulted in increases in the poly-beta-hydroxybutyrate content on lactate and pyruvate of up to similar to 15% and similar to 20%, respectively. An increase in pH caused a decrease in H-2 production and an increase in poly-beta-hydroxybutyrate accumulation on lactate under nitrogen-deprived conditions. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.