The spectrum of antimicrobial activity of the bacteriocin subtilosin A

Abstract

Background: Bacterocins are antimicrobial peptides produced by bacteria with a relatively narrow range of activity against closely related organisms. Subtilosin A is a bacteriocin produced by Bacillus subtilis that has activity against Listeria monocytogenes, which might indicate antimicrobial activity unusual for bacteriocins.Objectives: To examine the antimicrobial activity and factors affecting the activity of subtilosin A against a range of potentially pathogenic bacteria. Methods:The peptide was purified from cultures of B. subtilis and the MIC determined for 18 species of bacteria using a microdilution methodology. The extent of capsule formation was determined using microscopic examination of cells mounted in India ink. Protease mutants of a susceptible bacteria and mild heat shock were used to examine the effect of environmental stress on subtilosin A activity.Results: Subtilosin A proved to have antimicrobial activity against a wide range of bacteria including Gram-positive and Gram-negative bacteria and both aerobes and anaerobes. The peptide was less effective against capsulated forms of two Gram-negative bacteria than the non-capsulated strains of either. Heat shock but not protease activity also altered the effectiveness of the bacteriocin.Conclusions: Subtilosin A has limited antimicrobial activity against a number of human pathogens which, combined with its relative ineffectiveness against some capsulated pathogens, may limit its usefulness as a human therapeutic.

Bacteria Exhibiting Antimicrobial Activities; Screening for Antibiotics and the Associated Genetic Studies

“…The spectrum of activity was investigated and proved antagonism against a wide range of bacteria including Gram-positive and Gram-negative bacteria and both aerobes and anaerobes [18]. The production of mature subtilosin is based on the expression of the sbo-alb *Address correspondence to this author at the Department of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan; Tel: +92-42-99238530; Fax +92-42-99230481: E-mail: shahida@mmg.pu.edu.pk, genetic@brain.net.pk gene cluster encompassing the subtilosin structural gene sbo and genes involved in posttranslational modification, processing of presubtilosin and immunity [17,19].…”

Characterization of Bacterial Polysaccharide Capsules and Detection in the Presence of Deliquescent Water by Atomic Force Microscopy

“…Furthermore, we found that with ScanAsyst mode the polysaccharide capsules could be detected even in the presence of deliquescent water covering the capsule. C apsular polysaccharide (CPS) plays important biological roles for many microorganisms, such as nutrient uptake (17), protection against environmental stresses (15), biofilm formation (8), and survival against phagocytosis or antibiotics (3,19,20). Moreover, CPS is potentially economically important material (2, 6, 7).…”

Abh and AbrB Control of Bacillus subtilis Antimicrobial Gene Expression

“…Among the antimicrobials produced by B. subtilis 168 strains are sublancin (27), subtilosin A (2,35), bacilysocin (46), bacilysin (20,22,48), the SdpC sporulation delay toxin (8,14), the SkfA sporulation killing factor (1,14), and the TasA protein (37). The pleiotropic AbrB protein is known to play a role in regulating most of these antimicrobials in addition to numerous other genes expressed by postexponential-phase cells (22,31,36,37,54).…”