ISOLATION OF POTENTIAL ANTIMICROBIAL METABOLITE FROM ENDOPHYTIC Bacillus amyloliquefaciens DL06 OF CARNIVOROUS PLANT Drosera burmannii Vahl.

Abstract

Abstract

Objectives: Bacterial endophytes exploited for the production of antimicrobial substances have lead to the discovery of novel compounds of diverse chemical nature. This study was aimed at optimisation of cultural conditions for production of antimicrobial compounds by DL06 followed by extraction and partial purification of the active compound.

Methods: The leaf endophytic bacterium Bacillus amyloliquefaciens DL06 solated from carnivorous plant Drosera burmannii has been identified as a potent producer of antimicrobial metabolite. It was characterized (GenBank Accession no. MK696415, MCC Accession no. 4186), the cultural conditions for antimicrobial activity were determined, the active fraction was extracted and purified partially.

Results: Bacillus amyloliquefaciens DL06 produced maximum antimicrobial compound in tryptic soy broth and Davis Mingioli’s medium when grown under shake culture. Production of the antimicrobial metabolite has been optimized for the inoculum density, aeration, temperature, pH and carbon and nitrogen sources. The antimicrobial metabolite was extracted from the cell-free culture filtrate in butanol, and partially purified by column chtromatography and high performance liquid chromatography (HPLC).

Conclusions: The antimicrobial metabolite has been tentatively identified as quercetin and found to show spectrum of activity affecting a number of Gram-positive and Gram-negative bacteria and fungi.