Effects of grazing by flagellates on competition for ammonium between nitrifying and heterotrophic bacteria in chemostats

Article Abstract:

The effects of grazing at increasing carbon-to-nitrogen (C/N) ratios by Adriamonas peritocrescens on the competition for limiting amounts of ammonium between species of Nitrosomonas europaea and heteromorphic species of Arthrobacter globiformis in the presence of Nitrobacter winogradskyi in chemostats was investigated. The results showed that A. globiformis is more competitive than N. europaea. As the C/N ratios increased, nitrate concentrations decreased. The flagellates selectively predated on the nitrifying bacteria, resulting in higher nitrifying activity per cell in the presence of flagellates.

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Competition for ammonium between nitrifying and heterotrophic bacteria in continuously percolated soil columns

Article Abstract:

Nitrosomonas europea, Arthrobacter globiformis and Nitrobacter winogradsky, which are chemolithotrophic, heterotrophic and nitrifying species of bacteria, respectively, were grown in a continuously percolated column to study the competition for limiting amounts of ammonium. The results showed that the numbers of nitrifying bacteria were not necessarily correlated to their activities. Furthermore, the nitrifying bacteria were less competitive than the heterotrophs, although they could survive as viable inactive cells which could be reactivated during periods of mineralization.

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Effects of grazing by flagellates on competition for ammonium between nitrifying and heterotrophic bacteria in soil columns

Article Abstract:

Soil columns containing the chemolithotroph Nitrosomonas europea and the heterotroph Arthrobacter globiformis in the presence of Nitrobacter winogradskyi were established to determine the effects of grazing by Adriamonas peritocrescens on competition for ammonium by nitrifying and heterotrophic bacteria. The results showed that flagellates had no effect on the outcome of competition, which A. globiformis invariably won. The presence of flagellates had different effects on the fate of ammonium in the soil columns at low and high concentrations of glucose.

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