Production of poly-3-hydroxybutyrate by Bacillus sp JMa5 cultivated in molasses media

A strain of Bacillus sp. coded JMa5 was isolated from molasses contaminated soil. The strain was able to grow at a temperature as high as 45 degreesC and in 250 g/l molasses although the optimal growth temperature was 35-37 d egreesC. Cell density reached 30 g/l 8 h after inoculation in a batch cultu re with an initial concentration of 210 g/l molasses. Under fed-batch condi tions, the cells grew to a dry weight of 70 g/l after 30 h of fermentation. The strain accumulated 25-35%, (w/w) polyhydroxybutyrate (PHB) during ferm entation. PHB accumulation was a growth-associated process. Factors that no rmally promote PHB production include high ratios of carbon to nitrogen, an d carbon to phosphorus in growth media. Low dissolved oxygen supply resulte d in sporulation, which reduced PHB contents and dry weights of the cells. It seems that sporulation induced by reduced supply of nutrients is the rea son that PHB content is generally low in the Bacillus strain.