Toxic effects of linear alkylbenzene sulfonate, anthracene and their mixture on growth of a microbial consortium isolated from polluted sediment

the aim of this study was to determine the effect of linear alkylbenzene sulfonate (las), anthracene and a las-anthracene mixture on the growth of a microbial consortium isolated from polluted sediment. the microbial consortium was grown in a sterile glass bottle with mineral medium containing 1 g/l of glucose. microbial growth inhibition produced by las, anthracene and combinations of las and anthracene was determined by viable count in nutritive agar; inhibitory concentration 50 (ic50) was calculated. the concentrations evaluated were 0.16, 0.8, 1.6, 16 and 160 mg/l of las or anthracene. the las-anthracene mixtures were prepared by fixing either las or anthracene at 0.16 mg/l while increasing the other compound at the above concentrations. microbial growth was sensitive to las at an ic50 of 8.22 and to anthracene at an ic50 of 5.2 mg/l. in the las-anthracene combination, if las concentration was fixed and anthracene concentration varied, ic50 (5.92 mg/l) was similar to ic50 for anthracene alone. in contrast, the inhibition effect was diminished when anthracene remained constant and las concentration was increased (ic50: 70.11 mg/l). the sediment microbial populations were capable of degrading the las-anthracene mixture if the concentration of both compounds were at 0.16 mg/l.