Properties of alkaliphilic halophiles

Abstract

Microorganisms capable of growth under highly alkaline conditions have been isolated from natural habitats. The isolation process utilized pH levels of 9.7 to 11.0, salts of 4.0 to 5.0%, temperatures of 45-50°C, and anaerobic conditions. Four isolates are described as gram-positive, spore-forming, motile, catalase-positive rods. This indicates that they are in the genus Bacillus. The culture characteristics of these and two other isolates were evaluated. All six strains tolerated up to 11.0% salts in the growth medium. The purpose of this study was to evaluate these microorganisms for their potential use in combination with an alkaline flood for enhanced oil recovery. Useful products in in situ microbial-enhanced oil recovery include gases, surfactants, polymers and acids. The best gas producer was Bacillus strain ACP-1 which evolved an average of 2.11 ml gas per ml medium in 96 h. Bacillus strain ACP-1 reduced the surface tension of the growth medium from 50.3 mN/m to an average of 44.1 mN/m. Another aspect of this research project included investigation of the movement of these microbes through a porous medium. Various synthetic surfactants were found to improve movement through a porous system, while other surfactants improved gas production. © 1986 Society for Industrial Microbiology.