The project is supposed to be a part of long time research of bacterial denitrification at the mentioned department, where the kinetics of denitritication and its regulation is studied in Paracoccus denitrifîcams. This project should focus on one of the denitrification limiting factors, e.g. The availability of nitrate to the enzymes of denitrification pathway. The transport system involved in nitrate uptake will be studied using techniques of molecular biology. First, degenerate primers will be designe d on the basis of sequence homology with nitrate transporters from other sources. The primers will be then used to isolate the genes involved in P. denitrificans nitrate transport. Further regulation factors will be searched for by comparison of expressi on patterns of the bacterium under both the aerobic and anaerobic conditions on the level of mRNA. An alternative way would be transposon Tn5 mutagenesis, followed by screening for inability to utilize low concentrations of nitrate. Isolated genes will b