A Pseudomonas thrives in high concentrations of toluene

Abstract

TOLUENE, like many organic sovents, is highly biotoxic and kills most microorganisms at low concentrations (0.1% v/v). It is often used therefore to sterilize microbial cultures and lyse bacterial cells in the assay of bacterial enzymes^1–3. The physiological basis of such solvent toxicity, however, remains poorly characterized. Although some microorganisms, including Pseudomonas^4–6 , Achromobacter⁴ and Nocardia⁷ , can assimilate toluene, their toler-ance for the solvent is less than 0.3% (v/v). We report here the discovery of a variant strain of Pseudomonas putida which is capable of growing in media culture containing more than 50% (v/v) toluene or high concentrations of cyclohexane, xylene, styrene and heptanol. By studying this unusually tolerant strain we show that the relative toxicities of different solvents are determined by their polarities.