CAPACITY OF PLANKTONIC AND EPILITHIC MICROBIAL ASSEMBLAGES FROM WATEROF THE DANUBE TO BIODEGRADE SODIUM DODECYL-SULFATE AND DIOCTYL SULFOSUCCINATE

The capacity of planktonic and epilithic assemblages to degrade sodium dodecyl sulphate (SDS) and dioctyl sulphosuccinate (DOSS) in samples taken in four terms covering a one-year seasonal cycle from water of t he Danube was estimated under simulated environmental conditions. Slow er degradation of DOSS, especially in the winter period, was observed in comparison with SDS. The degradation of SDS by both microbial assem blages began immediately and accelerated during 48-96 h of cultivation . DOSS removal was slower and very often the acceleration of the degra dation rate occurred in two transient phases. Biodegradation was accom panied by both increase in the CFU number and the biomass yield repres enting a substantial share from whole microbial assemblages. At the sa me time surfactant utilization and biomass production was reflected in enhanced protein and DNA synthesis. DNA synthesis was the most intens ive at 48 h; while protein synthesis at 96 h of biodegradation. Elevat ion of concentrations of the applied surfactants stimulated the biodeg radation rate. The highest rate of SDS removal was observed at the con centration of 100 mu l.ml(-1), while that of DOSS at 50 mu g.ml(-1).