Molecural ecological analysis of symbiotic microorganisums of beetle inhabit in forest

点击翻译按钮获取中文摘要

The larvae of Japanese horned beetle, Ttypoxylus dichotoma (L.), inhabit in forests of Shiia sieboldii or Fagus crenata, and are assumed to play an important role as decomposer in ecosystem of the forests. Various glycanase activities were detected from the digestive tracts of larva, and microorganisms inhabiting the tracts seem to attribute at least some of these activities. In addition, the contents of midguts are alkaline, suggesting that the digestive tracts are quite unique niches in soil environments. In this research, microbial flora of the digestive tracts, midguts and hindguts, of the larvae were examined by the cultivating method and the non-cultivating method. Using glucose or xylan as carbon source we isolated aerobic microorganisms under neutral or alkaline pH, and their 16S rDNA were partially determined. Total DNAs were extracted from the samples and analyzed by the PCR-DGGE method. By the cultivating method, microorganisms belonging to only limited number of genera are … More detected, and the genera grown on alkaline media were different from those on neutral media. PCR-DGGE analysis suggested that the specific microorganisms might be dominant in hindgut of larvae where as no or few dominant bands were detected in midgut.In the digestive tract of the larvae of the beetle detected strong hydrolyzing activity to xylan that is a major hemicellulose of broadleaf trees. Since the contents of digestive tracts are alkaline xylanolytic alkaliphiles might exist the tracts. We isolated the xylanolytic bacteria from the larvae of digestive tracts, feces, and leaf litters that larvae inhabited using the alkaline media contain xylan as carbon source. We isolated seven strains from the midguts, eight strains from the hindguts, and eight strains from the feces, and eight strains from the leaf litters. By the result of 16S rDNA sequence analysis, the majority of xylanolytic alkaliphiles from the digestive tracts of larvae were Bacillus. The gram positive bacteria with strong xylanolytic activity were isolated from leaf litters and feces. The xylan hydrolyzing activity showed its maximum at pH of 9.3, and is stable at a range between pH 5 and 11. Less