This study was designed to analyze the diversity of aerobically growing bacteria in a landfill area, compared to those from a forest and a cultivated area at four different depths. The viable cell number of aerobes in the incineration ash layer (3.5(±0.4)×10²/g) was 10³- to 10⁴-fold lower than those in the other areas. On 16S ribosomal DNA similarity analysis of a total of 727 colonies, only the class Bacilli was detected in the incineration ash layer whose pH was extremely high (12.8), while five to seven classes were detected in the forest and the cultivated area. Of the genus Bacillus, B. licheniformis and the recently discovered Bacillus were predominant in the incineration ash layer. These analyses indicate that the incineration ash layer of a landfill might be a source that includes valuable or hitherto unreported Bacillus species.

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Clay wall (also called mud wall in English and tsuchikabe in Japanese) material is used in traditional Japanese buildings. Clay wall material is manufactured by fermenting a mixture of clay, sand, and rice straw. A culture-independent study based on 16s rRNA sequences revealed that Clostridiales of Firmicutes, alpha-, gamma- and delta-proteobacteria of Proteobacteria, and Acidobacterium of Acidobacteria exist in the clay wall material. Of these, we focused on Clostridium and Geobacter and their possible roles in the degradation of the cellulose component of the straw and the reduction of ferric iron in the clay during fermentation.

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The budding yeast Saccharomyces cerevisiae Σ1278b contains the MPR1 gene encoding N-acetyltransferase, which detoxifies the L-proline analog L-azetidine-2-carboxylate (AZC). Of 131 yeasts tested, AZC acetyltransferase activity was detected in 17 strains of 41 strains that showed AZC resistance. Degenerate-PCR analysis revealed that two strains, i.e., Candida saitoana AKU4533 and Wickerhamia fluorescens AKU4722, contained a DNA fragment highly homologous to MPR1. This indicates that AZC acetyltransferases are widely distributed in yeasts.

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