Ecological Effects Of Bacillus Subtilis And Kasugamycin On Microorganisms In Phaeozen

The effects of two microbial pesticides(Bacillus subtilis and Kasugamycin) on soil microbial communities, soil respiration and soil enzymes were studied by using phaeozem samples with a short-term treatment in this thesis. The results will be valuable to provide some fundamental data for assessing the environment safety and scientific application, and to build up alert index systems in phaeozem treated by Bacillus subtilis and Kasugamycin. The main results are reported as follows:1. Soil microbial communities populationThe influences of Bacillus subtilis and Kasugamycin on the cultural microorganisms in phaeozem, using traditional selective plating and direct viable counts methods.The results showed that the population of bacteria,fungi and actinomycetes were stimulated with the level of Bacillus subtilis increased in phaeozem comparing with the control (without Bacillus subtilis), and higher level, the more stimulate; and it was obviously that bacteria,fungi and actinomycetes were stimulated significantly when the soil samples treated with Bacillus subtilis at the level of 3200mg/kg during the whole culture time. The stimulated effects of Bacillus subtilis on the soil microbes were bacteria> actinomycetes> fungi.The results showed that the population of bacteria,fungi and actinomycetes were all stimulated after the application of Kasugamycin during the whole culture time; low level (500mg/kg) comparing with the control did not have great change, but it was obviously that bacteria,fungi and actinomycetes were stimulated significantly when the soil samples treated with Kasugamycin at the level of 25000mg/kg and 50000 mg/kg.2. Soil respirationThe soil respiration was stimulated after Bacillus subtilis and Kasugamycin treatment during the whole culture time, and the higher the applied level was,the stronger the stimulation was observed. The soil respiration was stimulated significantly when the soil samples treated with Bacillus subtilis at the level of 1012 mg/kg and 3200 mg/kg and Kasugamycin at the level of 25000mg/kg and 50000 mg/kg.3. Soil enzymes activitiesThe activity of urease was stimulated, however, catalase was little affected by Bacillus subtilis during the whole culture time. With the increasing dose level of Bacillus subtilis, the stimulation rate of urease increases except the third and 35th day, and the activitiy of urease was stimulated significantly when the soil samples treated with Bacillus subtilis at the level of 1012mg/kg and 3200mg/kg.The activity of urease was stimulated by Kasugamycin, with the increasing dose level of Kasugamycin, the stimulation rate of urease increases except the 7th day; and it was obviously that their activities have been stimulated significantly during the whole culture time. Under the effect of Kasugamycin, catalase activity show the"inhibition→stimulation", but effects of inhibition and stimulation in different level was unconspicuous.