Abstract
Two dodecyltrimethylammonium bromide (DTAB)-degrading bacteria were isolated from activated sludge of a wastewater treatment plant (WWTP). The bacteria identified as Pseudomonas fluorescens was called F2 and F7. The BOD biodegradability of DTAB by these bacteria were relatively high and similar to that of the activated sludge. F7 grew in a basal medium containing DTAB as the sole carbon source, producing trimethylamine (TMA) from DTAB by a N-dealkylation process. Then, the intermediate TMA was degraded to dimethylamine (DMA) by N-dimethylation as a second step. The pathway of the degradation of DTAB by this strain was the same as that of the activated sludge. On the other hand, Ps. fluorescens F2 degraded DTAB to TMA, but TMA was not further degraded. As for Ps. fluorescens F7 degrading activity, anionic compounds, such as fatty acids and sodium dodecyl sulfates (SDS), enhanced the degradation and dodecanoate became the carbon and energy source for this bacteria strain. These results demonstrate that monoalkyl quaternary ammonium compounds are ultimately degraded through N-dealkylation and mineralization, by a bacterium isolated from activated sludge.
