Abstract:
The aim of this work was to evaluate three different bacterial strains for their ability to accumulate
poly-3-hydroxybutyrate (PHB) using pentose sugar rich hydrolysate generated from acid pretreated rice
straw as the sole carbon source. Out of these, Bacillus firmus NII 0830 showed maximum PHB production.
Acid pretreated black liquor contained sugars and sugar degradation products such as formic acid, acetic
acid, furfural and hydroxymethyl furfural. The bacterium grew in the hydrolysate medium without any
detoxification and it could accumulate 1.9 g/l biomass with 1.697 g/l PHB and the PHB content in the cell
was 89%. This was the highest value ever reported from Bacillus species. The optimum conditions for
the fermentation media were an inoculum concentration of 6.5%, 90 h of incubation and 0.75% of xylose
concentration. The characterization of extracted polymer was carried out by FTIR, 1H and 13C NMR which
showed characteristics similar to that of the standard PHB from Sigma.
