Microbial Communities in Different Season Vary with the Type and Degree of Deterioration at Jinsha Earthen Site

Abstract

To clarify the relationships between soil microbial communities and environmental factors in earthen site deterioration, we used culture-independent and culture-based methods to analyze bacterial and fungal community composition and functions in soils with different types and degrees of deterioration from different season at Jinsha earthen site, Chengdu, China. The concentrations of Mg2+ and SO42- were higher in the severe deterioration degree soil than in the minor deterioration degree soil in all three deterioration types. The Chao1 richness and Shannon diversity of bacteria in the blister and yellowing type deterioration were higher in the summer than in the winter, while the richness and diversity of fungi were lower in the summer than in the winter samples. The differences in bacterial and fungal communities were associated with differences in Na+, K+, Mg2+ and Ca2+ contents. Based on both the relative abundances in amplicon sequencing and isolated strains, the bacterial phyla Actinobacteria, Firmicutes and Proteobacteria, and the Ascomycota genera Aspergillus, Cladosporium and Penicillium were common in all soils. The OTUs enriched in the severe deterioration degree soils were mostly Actinobacteria and Proteobacteria, whereas the Firmicutes OTUs differentially abundant in the severe deterioration degree were all depleted. All bacterial isolates produced alkali, implying that the deterioration on Jinsha earthen site may be accelerated through alkali production. The fungal isolates included both alkali and acid producing strains. The fungi with strong ability to produce acid were mainly from the severe deterioration degree samples and were likely to contribute to the deterioration. Taken together, the interaction between microorganisms and environment may accelerate the deterioration process of Jinsha earthen site.

Keywords: rthen site, Deterioration, Bacteria and fungi, Function