Analysis of PCR products for PHB production in indigenous <i style="">Pseudomonas </i>sp. LDC-5

Abstract

Poly-<img src='/image/spc_char/beta.gif'>-hydroxybutyric acid (PHB) and similar bacterial polyesters are promising candidates for the development of environment-friendly, totally biodegradable plastics. The cost of these biopolymers is 25% more than the synthetic polymers that prevents their usage in wider range of applications. In order to reduce the cost, much effort has been made to screen the promising indigenous PHB producing strain in the present study. As a first step, among thirty scl (Short-Chain-Length) positive strains screened, the most promising mcl (Medium Chain Length) PHA positive indigenous isolate, <i style="">Pseudomonas </i>LDC-5 was selected for further characterization. The nucleotide sequence analysis of the specific PCR product revealed open-reading frames probably relevant for PHA biosynthesis. The similarity search for nucleotide sequence exhibited 92% homology with <i style="">Pseudomonas </i>sp.<i style=""> </i>The amino acid sequences of the putative proteins deduced from these genes indicate that they encode a PHA synthase, which exhibited 96% amino acid identity with PHA synthase from <i style="">Pseudomonas putida. </i>Sequence alignment of the partial sequence of PHA synthase genes and putative protein showed conserved signatures. Phylogenetic analysis further places the origin of indigenous isolate closer to <i style="">P. putida.</i> The partial sequence of PHA synthase was submitted in EMBL and obtained the accession number AJ586810. FT-IR spectral analysis confirmed the presence of strong characteristic ester carbonyl band at 1733cm^-1. The identification of this novel biopolymer producing strain reveals a capability for the synthesis of technically interesting biopolymers in future.