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Objective: The aim of this study was to purify and characterize bacteriocin from the soil isolate Bacillus subtilis GAS101, and to determine its antimicrobial as well as antibiofilm potential. The purified bacteriocin was further analyzed and evaluated for mammalian cell cytotoxicity and the possible mode of action. Material and Methods: Bacteriocin from B. subtilis GAS101 (an animal husbandry soil isolate) was partially purified and checked for antimicrobial and antibiofilm activity against gram-positive and gram-negative bacteria. The molecular weight of bacteriocin was determined using tricine SDS-PAGE gel. The stability of bacteriocin was investigated at various temperatures and pH levels, and its sensitivity towards 8 enzymes and 6 chemicals was determined. Cytotoxicity analysis was performed on a Vero cell line by a tetrazolium dye-based assay. Scanning electron microscopy (SEM) of bacteriocin-treated bacteria was carried out to determine the possible mode of action. Results: Bacteriocin from B. subtilis GAS101 was a potential inhibitor of both the indicator organisms (Staphylococcus epidermidis and Escherichia coli), and had a molecular weight of approximately 6.5 kDa. An in situ gel assay showed a zone of inhibition corresponding to the estimated protein band size. Bacteriocin was stable and showed antibacterial activity in broad ranges of temperature (30–121°C) and pH (2–12). It was sensitive to 4 proteolytic enzymes, which indicated its proteinaceous nature. Bacteriocin showed > 70% cell viability on the mammalian Vero cell line. SEM depicted that the bacteriocin was able to disrupt the bacterial cell membrane as its probable mode of action. Conclusion: Thermostable and pH-tolerant bacteriocin from B. subtilis GAS101, of about 6.5 kDa, showed broad-spectrum antimicrobial and antibiofilm activity. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to purify and characterize bacteriocin from the soil isolate Bacillus subtilis GAS101, and to determine its antimicrobial as well as antibiofilm potential. The purified bacteriocin was further analyzed and evaluated for mammalian cell cytotoxicity and the possible mode of action.Material and Methods: Bacteriocin from B. subtilis GAS101 (an animal husbandry soil isolate) was partially purified and checked for antimicrobial and antibiofilm activity against gram-positive and gram-negative bacteria. The molecular weight of bacteriocin was determined using tricine SDS-PAGE gel. The stability of bacteriocin was investigated at various temperatures and pH levels, and its sensitivity towards 8 enzymes and 6 chemicals was determined. Cytotoxicity analysis was performed on a Vero cell line by a tetrazolium dye-based assay. Scanning electron microscopy (SEM) of bacteriocin-treated bacteria was carried out to determine the possible mode of action.Results: Bacteriocin from B. subtilis GAS101 was a potential inhibitor of both the indicator organisms (Staphylococcus epidermidis and Escherichia coli), and had a molecular weight of approximately 6.5 kDa. An in situ gel assay showed a zone of inhibition corresponding to the estimated protein band size. Bacteriocin was stable and showed antibacterial activity in broad ranges of temperature (30-121°C) and pH (2-12). It was sensitive to 4 proteolytic enzymes, which indicated its proteinaceous nature. Bacteriocin showed > 70% cell viability on the mammalian Vero cell line. SEM depicted that the bacteriocin was able to disrupt the bacterial cell membrane as its probable mode of action.Conclusion: Thermostable and pH-tolerant bacteriocin from B. subtilis GAS101, of about 6.5 kDa, showed broad-spectrum antimicrobial and antibiofilm activity. [ABSTRACT FROM AUTHOR]

Staphylococcus epidermidis has emerged as the main causative agent for graft-related and nosocomial infections. Rampant use of antibiotics and biofilm formed by the organism results in poor penetration of the drug and further aggravates the antibiotic resistance, emphasizing an urgent need to explore alternative treatment modalities. Antimicrobial peptides (AMPs), produced as effector molecules of the innate immunity of living organisms, have therapeutic potential that can be used to inhibit the growth of microbes. In addition, the susceptibility of a microbe to become resistant to an AMP is relatively low. The AMPs are amphipathic peptides of 12-100 residues, which have broad-spectrum activity against microbes. There are scattered reports of AMPs listed against S. epidermidis and there is an urgent need to systematically study the AMPs. Various natural AMPs as well as synthetic peptides have been investigated against S. epidermidis. These peptides have been shown to inhibit both planktonic culture and S. epidermidis biofilm effectively. The multiple modes of action in killing the organism minimize the chances for the development of resistance. This review focused on various natural and synthetic peptides that demonstrate activity against S. epidermidis. [ABSTRACT FROM AUTHOR]