Screening of Significant Medium Components for Biosurfactant Production by Potential Bacteria of DSW17 using Plackett- Burman Experimental Design and Its Application as Food Preservative Agent

Abstract

Biosurfactant or microbial surfactants produced by variety of microbes are capable of reducing surface and interfacial tension and have a wide range of industrial and environmental applications. Potential biosurfactant-producing microbe was successfully isolated from the Laboratory of Bioenergy and Bioprocess, Research Center for Biotechnology, LIPI. Based on the analysis of 16S rRNA sequence and phylogenetic tree, microorganisms DSW17 was 97% identical to Bacillus altitudinis TAZ1-5 HQ236061. In the present research, statistical screening of media components for biosurfactant production by microorganism DSW17 was carried out using Plackett-Burman experimental design. Nine out of eleven factors of the production medium were found to be significantly affecting the production process of biosurfactant. FeSO4.7H2O, NaNO3, waste vegetable oil, CaCl2.2H2O, K2HPO4 and sucrose were directly proportional to the biosurfactant production while ZnSO4.7H2O, KH2PO4 and MgSO4.7H2 showed inversely proportional correlation with the biosurfactant production in the selected experimental range. Several modified mediums were formulated based on the statistical Plackett-Burman screening result in order to validate the optimum media composition in producing biosurfactant. Modified medium combination 1 (MM1) as an optimized medium (2.13 g/L) showed 124% increase in biosurfactant production over the unoptimized medium or MM6 (0.95 g/L). From the validation result obtained, it was known that the optimized medium was proven to show better performance in the biosurfactant production, while it was also economically applicable compared to the other modification media. The biosurfactant produced by Bacillus sp. DSW17 in optimized medium showed antimicrobial activity against spoilage microorganisms. Based on the antimicrobial properties of the biosurfactant, it was then applied as a preservative agent in foods (tofu, beef and chicken meat) and also beverages (strawberry and tomato juice). Biosurfactant from Bacillus sp. DSW17showed the ability to extend the shelf life of tofu, strawberry juice and tomato juice for 4 hours, 2 hours and 1 hour, respectively. While in beef and chicken meat, biosurfactant were not able to extend its shelf-life.