Investigation of Antimicrobial Activity and Statistical Optimization ofBacillus subtilisSPB1 Biosurfactant Production in Solid-State Fermentation

Abstract

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.

Improvement of methyl orange dye biotreatment by a novel isolated strain, Aeromonas veronii GRI, by SPB1 biosurfactant addition

“…Processed sequences were subjected to Basic Local Alignment Search Tool (BLAST) alignment. The CLUSTALW program was used to make multiple alignments between all sequences using default parameters (Ghribi et al 2012). …”

“…Lately, we have reported that B. subtilis SPB1 could produce lipopeptide biosurfactants with highly emulsification activity (Ghribi et al 2012). It was demonstrated as enhancer of hydrophobic compound bioavailability and biodegradability and could be widely applied in bioremediation technology .…”

Isolation and Identification ofBacillusSpecies From Soil and Evaluation of Their Antibacterial Properties

“…Owing to the fact that Bacillus species have constructed antibiotics in the soluble protein structure and that these antibiotics have been inexpensive and more effective in studies accomplished to date, these microorganisms are desirable for commercial production (6,7). In recent years, many investigations have utilized the antimicrobial properties of Bacillus strains (8)(9)(10)(11)(12). In a study, Al-Ajlani determined that 54 of the 118 Bacillus strains isolated from soil samples demonstrated antagonistic activities against at least two or more strain from a panel of pathogenic and nonpathogenic microorganisms (13).…”

Biodegradation of diesel oil by a novel microbial consortium: comparison between co-inoculation with biosurfactant-producing strain and exogenously added biosurfactants

“…The first spectrum (a) shows a negative control prepared in the same conditions but without inoculation biodegradation. Certain strains of B. subtilis were able to produce biosurfactants (Bacosa et al 2010;Chander et al 2012;Ghribi et al 2012;Santos et al 2014) and degrade hydrocarbon (Lily et al 2012;Yuliani et al 2012). Other B. subtilis strains are well known by their ability to produce biosurfactant simultaneously with hydrocarbon degradation for enhancing hydrocarbon bioavaibility and uptake Gudina et al 2013;Yengejeh et al 2014).…”