Denitrifying Bacteria in Paddy Soils of the Taihu Lake Basin,China
摘要
This study attempted to determine the characteristics of the communities, the ecological factors, and the denitrifying enzyme activity for denitrifying bacteria found in the paddy soils of the Taihu Lake Basin, China. Samples of the six main soil types of the basin were taken from paddy fields with different fertilities. The total numbers of bacteria and denitrifying bacteria in the high fertility soils were much more than those in low fertility soils, and the number of denitrifying bacteria accounted for 49% to 80% of the total number of bacteria. The O2 content was an important ecological factor that affected denitrification. Of test the strains isolated from the paddy soils in the Taihu Lake Basin, some (e.g., Pseudomonas spp.) grew well under low oxygen partial pressure, while others (e.g., Bacillus spp.) had no strict predilection with O2 content. Another critical ecological factor was the nitrogen concentration. Three selected denitrifying bacteria grew better in aculture medium with 135 instead of 276mg L^-1 nitrogen. At the same time 67% of the test strains were able to reduce NO3^- to NO2^- and 56% had N2O reductase.