Songklanakarin Journal of Science and Technology (SJST) (Aug 2023)
Optimization of biosurfactant production by Bacillus thuringiensis c25 isolated from palm oil contaminated soil
Abstract
Biosurfactants of microbial origin have wide applicability because of their surface-active potentials. Bacillus thuringiensis c25 isolated from palm oil contaminated soil was used in the production of biosurfactant and the product was screened using emulsification stability test (E24), drop-collapse, oil spreading, blood hemolysis and surface tension tests. The effects of incubation period, temperature, pH, and carbon source on biosurfactant production by B. thuringiensis c25 were investigated with a view to optimizing the production process. The biosurfactant produced was characterized using Fourier Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry. Initial assay showed emulsification index of 57.24 ± 0.25 %, oil displacement of 6.17 ± 0.21 mm and a positive drop-collapse test. Growth of B. thuringiensis at the optimal conditions of temperature 35 ºC, pH 7.0, glucose 10 g/L and yeast extract 1.5 g/L, reduced surface tension to 27.71 ± 0.88 mN/m and increased emulsification index to 84.78 ± 0.44%. Maximum biosurfactant production of 2.70 ± 0.04 g/L was obtained at 72 h. The characterization showed a lipopeptide biosurfactant type. Consequently, the B. thuringiensis of the present study is a good biosurfactant producer.