Enhancement of poly-beta-hydroxybutyrate accumulation in Nostoc muscorum under mixotrophy, chemoheterotrophy and limitations of gas-exchange.

Nostoc muscorum, a heterocystous cyanobacterium, produced poly-beta-hydroxybutyrate ( PHB) up to 8% (w/w) dry cells when grown photoautotrophically but 35% when grown mixotrophically with 0.4% (w/v) glucose and acetate after 21 d. Gas-exchange limitations under mixotrophy and chemoheterotrophy with 0.4% (w/v) acetate enhanced the accumulation up to 40-43% (w/w) dry cells, the value almost 5-fold higher with respect to photoautotrophic condition.