Effect of salinity gradients and heterotrophic microbial activity on biodegradation of XXXX in laboratory simulations of the estuarine environment.

@entity35786 @entity49470
The biodegradation of @entity49470 ( @entity35786 ), a synthetic replacement detergent builder, in the estuarine environment was examined by using a laboratory estuarine simulation. Two interdependent microcosms were used; each of five vessels was equilibrated with a saline gradient between 1.30 and 17.17%, with the final vessel subsequently being increased to a maximum salinity of 31.6%. Each microcosm was seeded simultaneously with heterotrophic bacteria from both fresh and saline sources. Viable counts demonstrated the ability of each microcosm to sustain a mixed heterotrophic bacterial community throughout the range of salinities for 183 days after a stabilization period. Isolation studies demonstrated that both systems contained four bacterial species, representatives of the genera Vibrio and Flavobacterium and members of the coryneform group and the family Enterobacteriaceae. Total bacterial numbers and species diversity decreased with increased salinity. @entity35786 was administered at low and high concentrations, one concentration to each microcosm, initially with the least amount of saline. Removal of both concentrations of @entity35786 occurred and was attributed to biodegradation after a period of bacterial acclimatization. Subsequent dosing of @entity35786 to vessels of higher salinity demonstrated that biodegradation was incomplete at observed mean salinities of greater than 9.18% at low influent @entity35786 concentrations and greater than 5.08% at high influent @entity35786 concentrations. Therefore, acclimatization was dose dependent. It was concluded that @entity35786 acclimatization at the higher salinities ceased because of salinity stress-induced failure of @entity35786 catabolism and not the disappearance of a particular bacterial species.
