OBJECTIVETo synthesize the ecofriendly nanoparticles, which is viewed as an alternative to the chemical method which initiated the use of microbes like bacteria and fungi in their synthesis.

METHODSThe current study uses the endophytic bacterium Bacillus cereus isolated from the Garcinia xanthochymus to synthesize the silver nanoparticles (AgNPs). The AgNPs were synthesized by reduction of silver nitrate solution by the endophytic bacterium after incubation for 3-5 d at room temperature. The synthesis was initially observed by colour change from pale white to brown which was confirmed by UV-Vis spectroscopy. The AgNPs were further characterized using FTIR, SEM-EDX and TEM analyses.

RESULTSThe synthesized nanoparticles were found to be spherical with the size in the range of 20-40 nm which showed a slight aggregation. The energy-dispersive spectra of the nanoparticle dispersion confirmed the presence of elemental silver. The AgNPs were found to have antibacterial activity against a few pathogenic bacteria like Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Klebsiella pneumoniae.

CONCLUSIONSThe endophytic bacteria identified as Bacillus cereus was able to synthesize silver nanoparticles with potential antibacterial activity.

Anti-Bacterial Agents ; chemistry ; pharmacology ; Bacillus cereus ; drug effects ; isolation & purification ; Escherichia coli ; drug effects ; Garcinia ; chemistry ; Klebsiella pneumoniae ; drug effects ; Metal Nanoparticles ; chemistry ; Microbial Sensitivity Tests ; Nanoparticles ; chemistry ; Phytotherapy ; methods ; Plant Extracts ; chemistry ; pharmacology ; Pseudomonas aeruginosa ; drug effects ; Silver ; chemistry ; pharmacology ; Staphylococcus aureus ; drug effects

Aims: The increased importance of biosurfactant in the recent past is mainly due to their applications in various industries ranging from petroleum to pharmaceuticals. Their biodegradability and environmental compatibility with low toxicity makes it even more interesting. Microbial production of biosurfactant is found to be a viable option as they are diverse, eco-friendly, facilitate large scale production, able to perform under extreme conditions etc. One class of microbes that is endophytes are known to show great potential in producing different varieties of medically and industrially significant biological compounds. The present study focuses on the screening and production of biosurfactant from endophytic bacteria. Methodology and results: Of all the isolates tested, one endophyte identified as Bacillus cereus HM998898 was found to produce maximum biosurfactant. Statistical method Plackett burman was used to optimize the media for the maximum production and the ideal composition was found to be KNO3 (1 g/L), Gingley oil (2 mL), K2HPO4 (2.5 g/L), KH2PO4 (0.75 g/L), MgSO4·5H2O (0.5 g/L), FeSO4.7H2O (0.005 g/L) and NaCl (0.025 g/L). The extracted biosurfactant was characterized and was identified to be glycolipid. This was further tested for biocompatibility against Fibroblast (3T3) cells and was evaluated for their anti tumor activity against Hep2 cells. Conclusion, significance and impact of study The biosurfactant produced was found to induce toxicity to cancer cells at appreciable levels while they remained non-toxic to normal cells supporting the possible applications of biosurfactant in medical field.