- Tolerance to sudden organic solvent shocks by soil bacteria and characterization of Pseudomonas putida strains isolated from toluene polluted sites
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About 1% of the soil indigenous bacteria survived upon a sudden addition of toluene to soil (10 % vol/wt). Two bacterial strains, MTB5 and MTB6, which utilize toluene as the sole carbon and energy source, were isolated from the soil contaminated with the huge quantity of toluene after 15 days incubation. The strains were Pseudomonas putida sensu stricto based on 16S rRNA sequences. Another strain, P. putida R1, isolated from a biofilm washed with toluene-contaminated waters was also examined regarding toluene degradation and tolerance. P. putida MTB6 grew on liquid medium with 10 % (vol/vol) toluene, while the other two strains did not grow at toluene concentrations > 0.1% (vol/vol). The three strains grew in the presence of 1% (vol/vol) ethylbenzene. All the strains displayed efflux pumps for removing toluene from the cell membrane. However, the efflux systems appeared more efficient in the MTB6 strain based on its higher tolerance to toluene and their increased capacity to remove toluene from the cell membranes. The solvent-tolerant MTB6 strain established best in soils contaminated with toluene and mineralized this aromatic hydrocarbon in situ.
- Ramos,Huertas,Molina,Rossello-Mora,Christensen,Duque,Mosqueda,Godoy,Ramos
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