Related Experiment Video
Updated: Mar 28, 2026

Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry
Published on: October 29, 2020
An Antimicrobial Metabolite from Bacillus sp.: Significant Activity Against Pathogenic Bacteria Including
Ajay G Chalasani1, Gunaseelan Dhanarajan2, Sushma Nema3
1Department of Biological Sciences, BITS Pilani- K. K. Birla Goa Campus Goa, India.
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.
Related Concept Videos
Clinical Significance of Antibiotic Resistance
Antimicrobial Effectiveness
Antimicrobial Proteins
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
Biological Methods for Microbial Control
Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
Inhibitors of Gram-positive Cell Wall Synthesis

