Study on Biological Synthesis of Cadmium Sulfide Nanoparticles by Bacillus licheniformis and Its Antimicrobial Properties against Food Borne Pathogens

Abstract

The green synthesis of cadmium sulfide (CdS) nanoparticles has been regarded as the most promising technique for their prospective applications in biological system. The bacterial strain Bacillus licheniformis has shown to be efficient in synthesizing cadmium sulfide nanoparticles. We report the effect on nanocrystal formation by varying the ratios of cadmium chloride and sodium sulfide ranging from 1:1, 2:1, 3:1 and 4:1 respectively. The resultant CdS nanoparticles was tested for antimicrobial activity against a range of food borne bacteria E coli, Bacillus licheniformis, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus and fungi Fusarium oxysporum, Aspergillus flavus and Penicillium expansum. The results showed that the CdS nanoparticles were crystalline in nature with size varying from 20-40 nm. The stability of nanoparticles was due to protein interaction which may have played an important role as capping agents. The antimicrobial activity showed that the CdS nanoparticles of ratio 4:1 of cadmium chloride and sodium sulfide at a concentration of 40 mg/ml showed highest zone of inhibition in Psedomonas aeruginosa (26.5±0.70) and Aspergillus flavus (27.8±0.28). The present study explains a simple, cost effective way of nanoparticle synthesis suitable for large scale production. The green synthesis approach extends the horizon of applications to biological systems as an effective medicinal agent.