PURIFICATION AND MOLECULAR ANALYSIS OF MICROBIAL DNA FROM COMPOST

A protocol was developed for the isolation of microbial DNA from compo st. The isolated DNA was shown to be highly polymerized, pure enough. for use with most molecular genetic techniques, and free of contaminat ing plant DNA. Two molecular genetic techniques used in comparisons of natural microbial communities were also optimized for comparisons of compost communities, and data obtained by the two techniques were comp ared in the analysis of the development of a microbial community in a single pilot scale reactor. The structures of the resident compost mic robial community at different times were compared by Random Amplified Polymorphic DNA (RAPD) fingerprinting: and by community DNA cross hybr idization. RAPD analysis yielded characteristic fingerprints of the co mmunity at different times as the compost reactor shifted from thermop hilic to mesophilic conditions. A limit of detection of unique species within the compost DNA was determined to be approximately 0.4% with t his technique. A higher degree of resolution was observed between diff erent samples using RAPD analysis than was observed with community cro ss hybridization. Significant asymmetries in reciprocal hybridizations were observed with community cross hybridizations between samples, po ssibly resulting from differences between samples in both complexity a nd base composition (%GC) of the DNA.