초록
<P><B>Abstract</B></P><P><B>Aim</B></P><P>Characterization of polyhydroxyalkanoates (PHA) accumulated by halophilic bacteria isolated from solar salterns.</P><P><B>Methods and Results</B></P><P>Twenty‐six halophilic isolates were obtained from solar salterns of Goa, India. They were screened for accumulation of PHA by Sudan black B, Nile blue A and Nile red stains. Strains H15, H16 and H26 were selected based on their intensity of Nile blue A/Nile red fluorescence. On the basis of phenotypic and genotypic characterization, the three isolates were identified as <I>Bacillus megaterium</I>. Growth kinetics and polymer accumulating capacity of strain H16 were studied in E2 mineral media with 2% glucose with/without NaCl. In the absence of NaCl, strain H16 accumulated PHA to 40·0% (w/w) of cell dry weight (CDW) at 42？h of growth, whereas in presence of 5% w/v NaCl, the culture showed longer lag phase of up to 24？h and accumulated a maximum PHA of 39% (w/w) CDW at 54 h of growth. The infrared spectra of both the polymers exhibited peaks at 1733·9？cm<SUP>−1</SUP> characteristic of C=O. Scans of <SUP>1</SUP>H nuclear magnetic resonance (NMR) showed a doublet at 2·5？ppm corresponding to methylene group (‐CH<SUB>2</SUB>), the signal at 5·3？ppm corresponded to methine group (‐CH‐), and another signal at 1·3？ppm corresponded to the methyl group (‐CH<SUB>3</SUB>). Scans of <SUP>13</SUP>C NMR showed prominent peaks at 20, 40, 67–68 and 170？ppm, indicating the polymer to be homopolymer of 3‐hydroxybutyrates. The polymer is stable up to a temperature of 160°C.</P><P><B>Conclusion</B></P><P>Three moderately halophilic isolates (strain H15, H16 and H26) capable of accumulating PHA were isolated from solar salterns of Ribandar Goa, India, and identified as <I>B.？megaterium</I> based on phenotypic and genotypic characterization. Strain H16 accumulated polyhydroxybutyrate in the presence and absence of NaCl up to 40% of its CDW.</P><P><B>Significance and Impact of the Study</B></P><P>This strain would be better suited for production of PHA at industrial level due to its tolerance to high concentration of NaCl.</P>