Abstract: In this study bacteriocin producing bacteria were isolated and enumerated from exotic fruits like dragon fruit (Hylocereus undatus), hog plum (Spondias mombin), Thailand litchi (Lychee chinensis), kiwi (Actinidia deliciosa), Thailand green apple (Ziziphus mauritiana) and were screened for production of bacteriocin. These fruits are imported from countries from Thailand Malaysia, Vietnam and some are also locally grown in India. Characterization and In vitro evaluation of the isolated bacteria were carried out to assess their in antimicrobial activity. Comparison of the Gram positive and Gram negative bacteria on these fruits were made. The bacteriocin producing microbes were tested for their antimicrobial activity against six indicator bacteria, namely Bacillus subtilis, Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella and Escherichia coli by agar diffusion assay. Finally one of the bacterial strain B4 showing inhibition against all the six indicator strains was selected for bacteriocin production. The biochemical tests of the strain indicated that it belongs to Bacillus megaterium. Physical parameters indicated that the optimum pH-8 and optimum temperature of 30° C. Maximum production of bacteriocin was observed in presence of ammonium chloride as a source of nitrogen and the molecular weight of bacteriocin was found to be 15kDa by SDS-PAGE.

Key words: Bacteriocin, Bacillus, molecular weight, antimicrobial activity.

| DOI: 10.17148/IARJSET.2022.9268