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Characterization of polyhydroxyalkanoates accumulated by a moderately halophilic salt pan isolate B acillus megaterium strain H 16
Author(s) -
Salgaonkar B.B.,
Mani K.,
Braganca J.M.
Publication year - 2013
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12135
Subject(s) - polyhydroxyalkanoates , halophile , bacillus megaterium , strain (injury) , microbiology and biotechnology , salt (chemistry) , salt pan , bacillales , bacillaceae , chemistry , bacteria , biology , bacillus subtilis , organic chemistry , genetics , anatomy , paleontology
Aim Characterization of polyhydroxyalkanoates ( PHA ) accumulated by halophilic bacteria isolated from solar salterns. Methods and Results Twenty‐six halophilic isolates were obtained from solar salterns of G oa, I ndia. They were screened for accumulation of PHA by S udan black B , N ile blue A and N ile red stains. Strains H 15, H 16 and H 26 were selected based on their intensity of N ile blue A / N ile red fluorescence. On the basis of phenotypic and genotypic characterization, the three isolates were identified as B acillus megaterium . Growth kinetics and polymer accumulating capacity of strain H 16 were studied in E 2 mineral media with 2% glucose with/without N a C l. In the absence of N a C l, strain H 16 accumulated PHA to 40·0% (w/w) of cell dry weight ( CDW ) at 42 h of growth, whereas in presence of 5% w/v N a C l, 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 −1 characteristic of C = O . Scans of 1 H nuclear magnetic resonance ( NMR ) showed a doublet at 2·5 ppm corresponding to methylene group (‐ CH 2 ), the signal at 5·3 ppm corresponded to methine group (‐ CH ‐), and another signal at 1·3 ppm corresponded to the methyl group (‐ CH 3 ). Scans of 13 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. Conclusion Three moderately halophilic isolates (strain H 15, H 16 and H 26) capable of accumulating PHA were isolated from solar salterns of R ibandar G oa, I ndia, and identified as B . megaterium based on phenotypic and genotypic characterization. Strain H 16 accumulated polyhydroxybutyrate in the presence and absence of N a C l up to 40% of its CDW . Significance and Impact of the Study This strain would be better suited for production of PHA at industrial level due to its tolerance to high concentration of NaCl.