Systematic screening of culturable endophytic bacteria for production of poly(3-hydroxybutyric acid) [P(3HB)] has resulted in the isolation of a potent strain identified as Bacillus cereus HAL 03 (GenBank Accession No. KR869088) from leaf tissue of Helianthus annuus L. Production of P(3HB) by this strain was influenced significantly by the quality as well as quantity of suitable carbon and nitrogen sources in the growth medium. At 2% (w/v) sucrose, the accumulated P(3HB) reached to a level of 50.46 % of its cell dry weight (CDW), whereas yeast extract (0.2%) as nitrogen source enhanced P(3HB) production and accounted for 53.19% of CDW. Moreover, the non-conventional carbon sources such as molasses further increased the production of the polyester up to 54.05% of its CDW. Finally, the identity of this intracellularly accumulated polyester was confirmed as a homopolymer of 3(hydroxybutyric acid) by the Fourier-transform infrared and proton nuclear magnetic resonance spectroscopic analysis. This study appears to indicate the first ever report of P(3HB) production by any strain of B. cereus endophytic to H. annuus L.
Key words: Bacillus cereus,Bacterial endophytes,biodegradable polyester, Helianthus annuus L.,polyhydroxyalkanoates,poly(3-hydroxybutyrate)
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