Molecular phylogenetic diversity of bacteria and its spatial distribution in composts

摘要

Aims: To investigate microbial diversity of swine manure composts in the initial stage and the spatial distribution due to gradient effect. Methods and Results: Samples in different locations of a composting pile were taken and analysed by using a culture-independent approach. Total community DNA was extracted and bacterial 16S rRNA genes were subsequently amplified, cloned, restriction fragment length polymorphism-screened and sequenced. Thirty-three unique sequence types were found among the 110 analysed positive clones from superstratum sample; 56 among 122 from middle-level sample and 32 among 114 from substrate sample, respectively. The sequences related to Clostridium sp. were most common in the composts. One hundred and thirteen out of 121 16S rDNA sequence types displayed homology with those in the GenBank database. Seven 16S rDNA sequence types were not closely related to any known species. The middle-level sample had the highest microbial diversity, containing unique sequences related to Lactosphaera pasteurii, Firmicutes sp., Aerococcus sp., Megasphaera sp. and Stenotrophomonas sp. Conclusion: Pile temperature significantly affected microbial community in the initial stage of the composting. Microbial community in different locations is quite different resulting from gradient effect. Significance and Impact of the Study: Results of this study reveal high bacterial diversity in manure composts, and provide molecular evidence to support gradient effect on microbial diversity in initial stage as well.