The solvent-tolerance of Gram-negative and Gram-positive bacteria were determined by the solvent parameter, log P. The solvent-tolerance of bacteria tested were in the following order, Pseudomonas> Escherichia, Serratia, Klebsiella > Proteus, Achrombacter, Acinetobacter > Alteromonas, Aeromonas, Flavobacterium > Alcaligenes, Bacillus > Agrobacterium, Micrococcus, Staphylococcus > Streptococcus > Leuconostoc, Lactobacillus > Corynebacterium, Chromobacterium, Brevibacterium, Rhodococcus.