Related Experiment Video
Updated: Aug 12, 2026
10:50
Qualitative and Quantitative Assays for Detection and Characterization of Protein Antimicrobials
Published on: April 10, 2016
Lytic effect of Bacillus subtilis elastase on gram-positive and negative bacteria
Indian Journal of Experimental Biology
|May 1, 1992
Summary
Bacillus subtilis elastase effectively lyses both live and treated Gram-negative and Gram-positive bacteria. Optimal bacterial lysis by this elastase occurs at pH 8.0, with peak activity observed in specific buffer solutions.
Area of Science:
- Microbiology
- Enzymology
- Bacterial Physiology
Background:
- Bacterial cell lysis is a critical process in microbiology with implications for antibiotic development and biotechnology.
- Enzymes capable of degrading bacterial cell walls are of significant interest for their potential applications.
- Bacillus subtilis is a well-studied bacterium known to produce various extracellular enzymes.
Purpose of the Study:
- To investigate the lytic activity of Bacillus subtilis 6a elastase against a range of Gram-negative and Gram-positive bacteria.
- To determine the optimal conditions (pH and buffer) for elastase-mediated bacterial lysis.
- To assess the differential sensitivity of live versus treated bacterial cells to elastase.
Main Methods:
- Preparation of bacterial cultures: Proteus vulgaris, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa (Gram-negative), and B. subtilis (Gram-positive).
- Treatment of bacterial cells: Freshly grown, heat-killed, and lyophilized cells were used.
- Assay of elastase activity: Lysis was assessed by measuring the degradation of bacterial cells under varying pH and buffer conditions (Tris-HCl, glycine-NaOH, Tris-maleate, cacodylate).
Main Results:
- Bacillus subtilis 6a elastase demonstrated lytic activity against both live Gram-negative and Gram-positive bacteria.
- Heat-killed and lyophilized bacteria exhibited increased sensitivity to elastase compared to freshly grown cells.
- Maximal bacterial lysis was achieved at pH 8.0.
- Elastase activity was highest in Tris-HCl and glycine-NaOH buffers at pH 8.0, followed by Tris-maleate and cacodylate buffers.
Conclusions:
- Bacillus subtilis elastase possesses broad-spectrum lytic capabilities against diverse bacterial species.
- Bacterial cell surface modifications (heat-killing, lyophilization) enhance susceptibility to elastase.
- The optimal pH for elastase-mediated bacterial lysis is 8.0, with specific buffer systems supporting maximal enzyme activity.
Related Concept Videos
01:28Biological Methods for Microbial Control
Biological agents offer an effective means of controlling microbial growth by leveraging natural processes like predation, competition, and the secretion of antimicrobial substances.Predatory bacteria such as Bdellovibrio species target and kill pathogens like Salmonella and E. coli. They are widely used in poultry farms to control infections. Myxococcus species help combat plant-pathogenic fungi. These naturally occurring predators serve as eco-friendly alternatives to chemical pesticides and...
01:12Bacterial Toxins
Bacterial toxins are sophisticated virulence factors that enable pathogenic bacteria to interact with, invade, and damage host tissues. These toxins fall broadly into two types: protein exotoxins, which are secreted into the environment and target specific host receptors, and lipopolysaccharide endotoxins, which are structural components of the bacterial outer membrane released primarily during bacterial lysis or membrane shedding. Exotoxins generally act more selectively, binding to cell...
01:20Determinants of Bacterial Pathogenicity and Virulence
Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
01:18Bacterial Gastroenteritis
Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...