Nitrifying and denitrifying bacteria in epiphytic communities of submergedmacrophytes in a treated sewage channel

A quantification of nitrifying and denitrifying bacteria present in differe nt compartments (water, sediments, submerged macrophytes) of a treated sewa ge channel was made to estimate their influence on the nitrogen balance and to assess the significance of macrophytes for nitrification and nitrogen c onversions in general. Considerable numbers of autotrophic and heterotrophic nitrifying and denitr ifiying bacteria were found to be present in the epiphytic communities of d ifferent species of submerged macrophytes of a treated sewage channel. Comparing the influence of the different compartments on total stream nitri fication and denitrification it could be concluded that dense beds of subme rged macrophytes particularly positively influence nitrification. Epiphytic nitrifiers were estimated to be as important for the total nitrification a s nitrifiers in the sediment. Denitrification was mainly taking place in th e sediment. The influence of the suspended nitrifiers and denitrifiers on t he nitrogen balance was assumed to be negligible.