Biosynthesis of polyhydroxybutyrate in Enterobacter sp. SEL2 and Enterobacteriaceae bacterium sp.PFW1 using sugar cane molasses as media

Abstract

The present research was conducted to check the cane molasses as a media for the production of polyhydroxybutyrate (PHB). Different dilutions of cane molasses were used in combination with water and mineral medium and in different ratios of carbon and nitrogen sources. Out of the 54 bacteria isolated from three types of organic waste contaminated environments, two were selected for their highest intensity of fluorescence under UV by Nile blue A viable colony staining method and they produced maximum amount of PHB from glucose (66.61±0.05% and 76.92±0.04%) in a shake flask culture at pH 7.0, 37°C and 150 rpm. The bacterial strains were identified as Gram negative rods and the 16S ribosomal ribonucleic acid (RNA) sequence similarity search showed 99 and 98% homology to Enterobacter sp. andEnterobacteriaceae bacterium respectively. In bacterial strains Enterobacter sp. SEL2 (JF901810) and Enterobacteriaceae bacterium PFW1 (JF901811), the polyhydroxybutyrate (PHB) biosynthesis from molasses was observed as 57.61±0.57% and 58.07±0.25% respectively at pH 7.0, 37°C and 150 rpm. The optimal time was 24 to 48 h for strain SEL2 and 48 to 72 h for strain PFW1. The best growth and polyhydroxyalkanoates (PHA) production was observed in media with 2% molasses and 0.2% ammonium sulphate in mineral medium (Media 11). The functional groups of the extracted PHA granules were identified as C=O group by Fourier transform infrared (FTIR) spectroscopy analysis and proton nuclear magnetic resonance (NMR) analysis confirmed it as a homopolymer of hydroxybutyrate. Key words: Polyhydroxyalkanoates (PHA), Sudan Black B, Nile blue A, molasses, polyhydroxybutyrate (PHB), Enterobacter, Enterobacteriaceae.