title: An Antimicrobial Metabolite from Bacillus sp.: Significant Activity Against Pathogenic Bacteria Including Multidrug-Resistant Clinical Strains.
abstract: In this study, the cell free modified tryptone soya broth (pH 7.4 ± 0.2) of Bacillus subtilis URID 12.1 showed significant antimicrobial activity against multidrug-resistant strains of Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes and Enterococcus faecalis. The partially purified antimicrobial molecule was found to be resistant to extremes of pH and temperatures and also to higher concentrations of trypsin and proteinase K. The antimicrobial molecule was purified by a three-step method that included reversed-phase high performance liquid chromatography (RP-HPLC). The minimum inhibitory concentration (MIC) values were determined for 14 species of bacteria using a microbroth dilution technique. The HPLC-purified fraction showed the MICs ranging from 0.5 to 16 μg/ml for methicillin and vancomycin-resistant Staphylococcus aureus (MVRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) strains. The molecular mass of the antimicrobial compound was determined to be 842.37 Da. The same antimicrobial fraction showed negligible haemolytic activity against human red blood cells even at a concentration as high as 100 μg/ml. Because of its significant antimicrobial activity at low MIC values coupled with its non-haemolytic property, it may prove to be a novel antimicrobial lead molecule.
authors.affiliation: Department of Biological Sciences, BITS Pilani- K. K. Birla Goa Campus Goa, India.
authors.forename: Ajay G
authors.initials: AG
authors.lastname: Chalasani
authors.affiliation: Department of Biotechnology, Indian Institute of Technology-Kharagpur Kharagpur, India.
authors.forename: Gunaseelan
authors.initials: G
authors.lastname: Dhanarajan
authors.affiliation: Central Lab OncQuest Laboratory Pvt. Ltd. (NABL) Indore, India.
authors.forename: Sushma
authors.initials: S
authors.lastname: Nema
authors.affiliation: Department of Biotechnology, Indian Institute of Technology-Kharagpur Kharagpur, India.
authors.forename: Ramkrishna
authors.initials: R
authors.lastname: Sen
authors.affiliation: Department of Biological Sciences, BITS Pilani- K. K. Birla Goa Campus Goa, India.
authors.forename: Utpal
authors.initials: U
authors.lastname: Roy
keywords: Bacillus sp.; Staphylococcus aureus; minimum inhibitory concentration; multidrug resistant-bacteria; non-haemolytic property; promising antimicrobial agent