[Evaluation of bacterial flora in contaminated soil as a countermeasure against H2S gas production]

Gas productions in illegal dumping sites and waste landfills have caused serious problems. The gas production was induced by bacterial flora inhabited soils. In order to construct a culture independent evaluation system of the soil bacteria, bacterial communities were analyzed quantitatively and qualitatively, about 16 soil samples at 4 sites, both using culture and culture-independent methods. The real time PCR method was developed for counting total bacterial number. Sequencing analysis of 16S rDNA amplified by a direct PCR method revealed that non-spore forming sulfate reducing bacteria and sulfur-oxidizing bacteria were detected at a similar frequency at an illegal dumping site near mountains. On the other hand, spore-forming sulfate reducing bacteria and Clostridium sp. were mainly detected in deep samples at reclaimed landfills from the sea, whereas sulfur-oxidizing bacteria was hardly detected. The result regarding sulfate-reducing bacteria was confirmed also by an anaerobic culture method. Culture-independent molecular analyses of soil bacteria would give us useful information for prediction of gas production and for the evaluation of soil equilibrium.