Toluene tolerance systems in pseudomonas

Abstract

Organic solvents such as monoaromatic hydrocarbons are highly toxic for living cells; however, most Pseudomonas putida strains are able to grow in the presence of low concentrations of these compounds. The cellular response toward the presence of organic solvents in the culture media is multifactorial. An early and quick response toward organic solvents is a decreased in the fluidity of the cell membrane via cis-trans isomerization of unsaturated fatty acids. This is followed by transcriptional reprogramming, leading to induction of stress-related functions and metabolic pathways to increase energy production. This energy is used by the microbe to extrude toxic compounds to the outer medium via efflux pumps of the RND (resistance, nodulation, and cell division) family-one of the most effective mechanisms for solvent tolerance. All of these processes concur in response to the presence of organic solvents in the majority of P. putida strains studied so far. There are a number of P. putida strains that have been described as highly solvent tolerant; for these strains, the action of one efflux pump (named TtgGHI in P. putida strain DOT-T1E) is required for full tolerance to a second phase of the organic solvent.