Antimicrobial activity of surfactants produced by Bacillus subtilis R14 against multidrug-resistant bacteria

Abstract

Lipopeptides represent a class of microbial surfactants with increasing scientific, therapeutic and biotechnological interests. The genus Bacillus is a producer of these active compounds, and among them B. subtilis produces surfactin, the most potent biosurfactant known. These compounds can act as antibiotics, antivirals, antitumorals, immunomodulators and enzyme inhibitors. In this work, the antimicrobial activity of biosurfactants obtained by cultivation of B. subtilis R14 was investigated against multidrug-resistant bacteria. During cultivation in defined medium, the surface tension of the medium was reduced from 54 mN/m in the beginning of the microbial growth to 30 mN/m after 20 hours. A crude surfactant concentration of 2.0 g/L was obtained after 40 hours of cultivation. A preliminary characterization suggested that two surfactants were produced. The evaluation of the antimicrobial activity of these compounds was carried out against 29 bacteria. Enterococcus faecalis (11 strains), Staphylococcus aureus (6 strains) and Pseudomonas aeruginosa (7 strains) and Escherichia coli CI 18 (1 strain) displayed a profile of well defined drug resistance. All strains were sensitive to the surfactants, in particular Enterococcus faecalis. The results demonstrated that lipopeptides have a broad spectrum of action, including antimicrobial activity against microorganisms with multidrug-resistant profiles.

Performance of a biosurfactant produced by Bacillus subtilis LAMI005 on the formation of oil / biosurfactant / water emulsion: study of the phase behaviour of emulsified systems

“…During this period the growth of microorganisms was not observed. This result can be attributed to the lipopeptides that present antimicrobial properties (Fernandes et al, 2007). This find can also be important for industrial applications, since, in the present case, a unique compound seems to have two important roles, as emulsifier, as well as antimicrobial agent.…”

Antifungal activity and bioactive compounds produced by Bacillus mojavensis and Bacillus subtilis

“…However, B. subtilis CWBI-B1567 produce only two types of lipopeptides (surfactin and iturin). These antifungal substances have been widely reported in Bacillus cultures such as B. amyloliquefaciens B94 (Yu et al, 2002) and B. subtilis JA (Chen et al, 2008; Fernandes et al, 2007). The two tested Bacillus strains produced cellulase and protease but the chitinase activity was not observed in either Bacillus strain.…”

Antagonistic Activity of Bacillus Bacteria against Food-Borne Pathogens

“…These compounds vary in structure and spectrum of activity and usually are responsible for antimicrobial effects of Bacillus bacteria [21,32]. In our study B. subtilis strains produced biosurfactants after cultivation in starch broth at 30°C.…”