不同土壤灭菌方法对土壤微生物活性的影响

The Effects of Different Soil Sterilization Treatments on Soil Microbial Activity

灭菌处理是土壤生态学、微生物学及其相关学科的一种重要研究手段,灭菌效果的好坏直接关系到后续研究的进行及其结果的准确性.常用土壤灭菌方法的灭菌效果及其评估仍然存在很大的不确定性.本文选取目前常用的3种灭菌方法,即高温高压蒸汽法、氯仿熏蒸法及辐射灭菌法,对不同背景的土壤样品进行灭菌.通过改变灭菌次数及灭菌间隔时间,观察灭菌后土壤微生物呼吸速率的变化.结果表明:(1)常规氯仿熏蒸灭菌后土壤微生物呼吸速率并不完全随着微生物量的减小而降低,说明单纯从土壤微生物量的角度不能准确界定灭菌效果以及解析微生物在土壤生态过程中的作用;(2)高温高压蒸汽比常规氯仿熏蒸和辐射灭菌方法有更好的土壤微生物灭活效果.实际应用中采用高温高压蒸汽灭菌时,建议采用灭菌2次、时间间隔为3d的灭菌处理;在相关研究中,对使用该方法灭菌效果的分析研究最佳时间不宜超过2d.

Soil sterilization is important in researches of soil ecology,microbiology and other relevant areas.The efficiency of soil sterilization affects greatly the reliability of subsequent research.However,there are still large uncertainties in how to assess soil sterilization efficiency of different techniques.In this study,we used three common methods of soil sterilization at present,i.e.high-temperature and high-pressure steaming,chloroform fumigation and radiation,to sterilize soils taken from forests and croplands.Variations of soil respiration before and after sterilization with different sterilization times and intervals were monitored.Our result indicated that（1）after sterilization by chloroform fumigation,soil microbial respiration did not decrease with the reduced soil microbial biomass,suggesting that changes of soil microbial biomass alone could not appropriately reflect sterilization efficiency,neither microbial contribution to soil ecological processes;（2）High-temperature and highpressure steaming could achieve a better inactivation of soil microbes than chloroform fumigation and radiation techniques.For achieving a best result of soil sterilization with high-temperature and high-pressure steaming technique,we recommended to sterilize soil 2 times with high-temperature and high-pressure steam with a time interval of 3 days,and to complete follow-on studies within 2 days after soil sterilization.