选择性呼吸抑制技术在土壤细菌和真菌生物量测定中的应用

The application of selective inhibition technique in the measurement of soil bacterial and fungal ratio

放线菌酮和链霉素可以选择性地抑制土壤中真菌和细菌的葡萄糖诱导呼吸作用，但抑制效果仅５０％ 左右。二者的最适用量每克土分别为８～１２ｍ ｇ 和４～８ｍ ｇ，培养时间以低于４ｈ 为好。在两个土壤上选择性呼吸抑制方法测定的结果与直接显微镜计数法所得的结果相当，但是，加入链霉素时，一个粘性土壤的葡萄糖诱导呼吸量不但不被抑制，反而随链霉素加入量的增加，诱导呼吸量增加，是否与其高的粘粒含量有关乃需要做进一步的研究。另还详细地讨论了应用此方法的有关问题。

Glucose induced respiration can be selectively inhibited by cycloheximide and streptomycin. The optimal quantities used in the three soils were 8～12 mg/g soil for cycloheximide and 4～8 mg/g soil for streptomycin. The incubation time following glucose addition was less than 4 hours. The total inhibition was about 50% of glucose induced respiration. The bacterial and fungal ratios for soil samples No. 1 and No.2 were comparable with these measured by agar film direct microscopy. It failed in determining the proportion of bacteria and fungi for a clay soil since substrate induced respiration increased as streptomycin addition. Whether the high clay content results in the failure measurement needs more study. The precaution using this techniques is discussed too.