Occurrence of nitrogen cycle bacteria in the Biebrza River

Occurrence of nitrogen cycle bacteria in the Biebrza River. This paper of the selected groups of nitrogen cycle bacteria in the Biebrza River was analysed. In the water samples the quantity of ammonifying bacteria, nitrifying bac- teria, proteolitic bacteria was estimated and also selected water quality indicators were analysed. Large quantities of proteolitic bacteria and am- monifying bacteria were found while the quantity of nitrifying bacteria was very small. Water qual- ity analyses proved high TOC concentrations and low nitrate as well as nitrite concentrations. It was found, that the mineral forms of nitrogen being the intensive product of organic matter degrada- tion is not released (low concentrations of am- monia), but it is accumulated in microorganisms cells. Low concentrations of ammonia are limit- ing for the number of nitrifying bacteria. The sea- sonal character of the occurrence of all analysed bacteria groups was as well found. The analytical procedure used was adjusted for bacteriological research on rivers of low anthropopressure.