ABSTRACT
Effective monitoring of microbial populations in environmental samples requires highly sensitive analytical methods. Studies of microbial communities using traditional techniques are incomplete because of their inherent inability to identify and quantify all types of contributing populations. In this chapter we have used molecular genetic approaches to compare the responses of microbial communities to organic and conventional management practices. Soil DNA was isolated by the direct lysis method and subjected to random amplified polymorphic DNA (RAPD) analysis. Soil DNA yields ranged from 2.44 to 4.56 μg/g in conventional and 4.08 to 6.76 μg/g in organic samples. RAPD patterns generated were characteristic for organic and 224 conventional soil types. Although some intennediate banding patterns were observed between the two soil types, major bands were distinguishable. The number of RAPD bands varied in both organic and conventional soil samples collected at 15-d intervals from April to July, which may indicate shifts in microbial populations. Thus, the RAPD technique has potential to detect changes in microbial population. However, the method requires processing of large number of replicate soil samples to generate reproducible polymorphic patterns.
