Abstract
In order to critically evaluate a landfull, it is very important to understand the mechanisms for organic decomposition and inorganic stabilization in the dumped layers. In this review, we focus on the distribution and structure of sulfate-reducers and methanogens, which are considered to be the major microorganisms for decomposition and stabilization of wastes, in a landfill site using molecular biological methods. Conventional methods for counting and measuring of bacterium have always required a long cultivation time and the value obtained after cultivation depends on the composition of nutrients, but from 1990 many useful methods based on molecular biology have been developed. This include quantitative PCR method, cloning analysis, DGGE, FRLP, TRFLP, slot-blot DNA (RNA) hybridization, and FISH. We have briefly reviewed these methods and examined the quantitative PCR method and cloning analysis on landfill leachates. Result showed that the distribution ratio of sulfate-reducers and methanogens was 15-30% and 2-3 %, respectively. The genus of Desulfomo-nile, which includes many species of higher dehalogenation activity to halo-compounds, was dominant. The the decomposition of halochemicals in the landfill sites due to wide distribution of the genus is a possible explaration for this.
