Distribution of denitrifying bacteria and its controlling factors in freshwater environments.

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Distribution of denitrifying bacteria and its controlling factors were investigated in freshwater environments. Denitrifying bacteria were counted by use of PY-Nitrate liquid medium and the most probable number method. The population (100-103 cells·ml-1) fluctuated more remarkably than that of aerobic heterotrophic bacteria in eutrophic pond and lakes. The ratio of the number of denitrifying bacteria to that of aerobic heterotrophic bacteria (D/Aeh) was between 0.0001 and 0.1 in those environments. In non-stratified eutrophic pond and lakes, the number of denitrifying bacteria tended to increase as the concentration of total nitrogen increased. In a stratified eutrophic lake, the D/Aeh ratio tended to increase as the concentration of dissolved oxygen decreased. Denitrifying bacteria in both water and attached substances in a polluted river tended to increase in number with the increase in BOD. The D/Aeh ratio in water and attached substances was higher than 0.01. Almost all denitrifying bacteria detected in the Himon-ya Pond, Lake Nakanuma and the River Tamagawa were gram-negative. Pseudomonas was the genus most frequently isolated from every type of water and attached substance.
日本陸水学会の論文