Quantitative selection of denitrifying bacteria in continuous cultures and requirement for organic carbon. II....

A mixed population of bacteria from industrial nitrogen wastewaters was incubated in continuous culture in medium containing 1000-1300 mg nitrate nitrogen per litre and maltose as a source of organic carbon. Maximal efficiency of denitrification was 8.6 mg N/1/h. The participation of denitrifying bacteria in the culture varied from 0% to about 80%, depending on the ratio of maltose concentration (CM) to nitrogen concentration (CN) in the medium. The optimal CM/CN ratio ensuring the greatest selection of denitrifying bacteria was 5.0, which calculated per organic carbon (CC/CN) gave the value of 2.1. The amount of maltose needed to denitrify a defined amount of nitrogens was negatively correlated (rxy = -0.95) with the frequency of denitrifying bacteria (XD) in the culture and was: CM = (4.20-0.026XD)CN. The denitrifying bacteria isolated from the studied continuous culture were dominated by Alcaligenes faecalis and Pseudomonas mendocina.