Resistance and degradability of heterotrophic bacteria in river waters to linear alkylbenzene-sulfonate.

LAS resistance and degradability were examined on 354 heterotrophic bacteria, isolated on PYG agar medium from a total of 18 river waters. All of the isolates tested could grow on the agar medium containing LAS at 3 mg/l, whereas 185 strains (52.2%) and 31 strains (8.7%) were tolerant to 30 mg/l and 300 mg/l of LAS, respectively. The predominant type among the most tolerant bacteria was Enterobacteriaceae (35.5%), that was reconfirmed by the classification of the highly resistant isolates from the other river water sample. LAS degrading ability was detected only in five of the 354 strains, all of which belong to Pseudomonas sp. but not to Enterobacteriaceae, and were sensitive to 300 mg/l of LAS, showing that the highly tolerant bacteria were not always LAS degrading bacteria.