Kinetic study and modeling of biosurfactant production using Bacillus sp

Background: Surfactants are one of the most important raw materials used in various industrial fields as emulsifiers, corrosion inhibitors, foaming agents, detergent products, and so on. However, commercial surfactant production is costly, and its demand is steadily increasing. This study aimed to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through fermentation. It also included the investigation of the effect of initial glucose concentration and the carbon to nitrogen ratio. Results: The biosurfactant yield was in the range of 1­2.46 g/L at initial glucose concentrations of 10­70 g/L. The optimum fermentation condition was achieved at a carbon to nitrogen ratio of 12.4, with a decrease in surface tension of up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation is proposed to predict the cell mass and biosurfactant production as a goodness of fit was obtained with this model. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension.

Lipopeptide production by Bacillus subtilis R1 and its possible applications

Abstract The possible application of a bacterial strain - Bacillus subtilis R1, isolated from an oil contaminated desert site in India, as biocontrol agent and its biosurfactant in microbial enhanced oil recovery are discussed. The biosurfactant production in minimal medium was carried out at different temperatures and salt concentrations, where it produced an efficient biosurfactant at 30-45 °C and in presence of up to 7% salt. It significantly reduced the surface tension from 66 ± 1.25 mN/m to 29 ± 0.85 mN/m within 24 h. In order to enhance the biosurfactant production, random mutagenesis of B. subtilis R1 was performed using chemical mutagen - ethyl methanesulfonate. Majority of the isolated 42 mutants showed biosurfactant production, but the difference was statistically insignificant as compared with parent strain R1. Therefore none of the mutants were selected for further study, and only parent strain R1 was studied. The biosurfactant was quite stable under harsh conditions for up to 10 days. The biosurfactant was extracted and characterized as similar to the lipopeptide group - surfactins and fengycin. The crude oil displacement experiments using biosurfactant broth in sand pack glass columns showed 33 ± 1.25% additional oil recovery. The strain also showed inhibition of various plant pathogenic fungi on potato dextrose agar medium.

The Development of Petroleum Microbiology in Institute of Microbiology, Chinese Academy of Sciences / 微生物学通报

A full and accurate review involved microbial prospecting of petroleum and gaseous hydro- carbon-oxidating bacteria, microorganisms and formation of petroleum and gas, production of organic acids, oil field microorganisms and enhancement of oil recovery. Hundred and five papers are quoted.

Characters and Oil Field Trial of Oil-Degrading Bacterium Strain NX-2 / 微生物学通报

Based on reservoir condition and fluid characteristics, the oil-degrading bacterial strain NX-2 was screened from Ma-2 fault block of Huabei oil field. Bacterial metabolism and the capability of improving oil property were evaluated on oxygen-deficient condition. At 87℃ which reservoir temperature is, artificial homogeneous core displacement experiment indicated the enhanced oil recovery of microbe was 7.1% higher than that of waterflooding. In experiment on individual well Ma-410, additional oil production of 669 tons was gained, and decreased water production of this trial well reached more than 3000 tons. These results demonstrated NX-2 could adapt to stratum conditions, enhance oil recovery and improve oil property as well.