Production and characterization of Polyhydroxybutyrate by Nocardia sp. RD13 isolated from agriculture rhizosphere soil

Abstract

This work was focused on to isolate polyhydroxybutyrate (PHB) producing actinobacteria from agriculture rhizosphere soil. The strain accumulated PHB 1.96 g/L, dry cell weight 66.55% under growth conditions in a nitrogen deficient medium containing galactose, with a maximum production at 72 h. Rice bran, corn starch, jack fruit seed powder, soy bean meal and groundnut husk were used as substrates for PHB production to reduce the cost of producing such biopolymer. Maximum PHB yield was obtained with groundnut husk (0.59 g/L) followed by rice bran (0.58 g/L) as sole nitrogen and carbon sources. The biopolymer was highly soluble in chloroform and peaked sharply at 235 nm upon digestion with concentrated H₂SO₄.  Recovered polymers were confirmed by Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR) and Thin layer chromatography (TLC). The potent isolate was identified as Nocardia sp. and designated as strain RD13. This study adds new genera to the members of the PHB producers.