Isolation of Solvent Tolerant Bacillus strains.
Sonja ISKEN* and Jan A.M. de BONT
Division of Industrial Microbiology, Department of Food Science, Wageningen Agricultural University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
Organic solvents like toluene are toxic for organisms because they accumulate in and disrupt cell membranes. However, in recent years exceptional strains have been isolated which can grow in the presence of a second phase of organic solvents previously believed to be lethal. Nevertheless, all of these solvent tolerant strains belong to the Gram-negative genus Pseudomonas. The question remains if only Gram-negative bacteria are able to adapt to the presence of toxic organic solvents or if the isolation conditions used benefit these bacteria.
In the work presented here we isolated several strains by using conditions which support growth of Gram-positive bacteria. Four strains grew also in the presence of a second phase of toluene in liquid cultures. They were classified as members of the genus Bacillus. We studied the effect of various organic solvents on the growth of these bacilli and demonstrated that the logPo/w concept used to describe the toxicity of organic solvents towards bacteria does not hold for these strains.
