Production of polyhydroxyalkanoates from Ralstonia eutropha using paddy straw as cheap substrate

Polyhydroxyalkanoates are polyesters of natural origin accumulated in form of intracellular granules by a wide variety of bacterial strains as candidates for biodegradable polymers, possessing material properties similar to the synthetic thermoplastics and elastomers. Paddy straw (lignocellulosic substrate) after hydrolysis was used as the carbon source for the production of polyhydroxyalkanoates from the predominant polyhydroxyalkanoates producer Ralstonia eutropha MTCC 1472. The effect of hydrolysed straw in the modified mineral salt media on bacterial growth and polyhydroxyalkanoates accumulation was analysed. Fourier transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry were performed on the extracted polyhydroxyalkanoates sample. At a dry cell weight of 19.2 g/L, 37.55 % polyhydroxyalkanoates accumulation was achieved; thus, paddy straw can be efficiently used as a cheap carbon source for industrial production of the polyhydroxyalkanoates.