Modeling microbial diversity across different soil ecosystems and environmental covariate selections in tropical SE Asian landscape

Abstract

Microbes play essential roles in the ecology of various environments and structure. Diversity of soil microbial communities is an important scientific interest in tropical landscape including in South East Asia. Soil environment in SE Asia is diverse and this influences the microbial diversity. Soil microbes in this study were collected using DNA isolation protocols and the whole microbial community structure of sampled soil was analyzed through next generation sequencing. Soil microbial identification was conducted by amplifying the 16S rRNA gene. Soils were sampled from 4 different environments in Sumatra and Kalimantan ecosystems representing plantation, swamp, peatland, and coastal ecosystems. Measured soil covariates including soil organic carbon C analyzed based on the Walkley-Black method and Kjeldahl method for N. Model of microbes in soil ecosystems were based on Akaike model selection (AIC) by testing the influence of soil covariates on soil microbial phylum. The microbial community was found to be comprising of a total number of 11 phyla. In soil of coastal ecosystem, microbial diversity at phylum level were dominated by Proteobacteria (82.3%), Actinobacteria (9.41%), Acidobacteria (4.7%), and the lowest was Bacteroidetes and Chloroflexi (0.58%). In plantation soil, the microbial abundance order was Firmicutes (41.6%) > Actinobacteria (29.7%) > Acidobacteria (20.0%) > Gemmatimonadetes (5.94%). The soil microbial abundance order in swamp was Proteobacteria (42.2%) > Acidobacteria (20.04%) > Bacteroidetes > (10.46%) > Actinobacteria (9.24%). In soil of peatland ecosystem, taxonomic assignments of microbial at the phylum level were dominated by Firmicutes (66.18%), Proteobacteria(16.94%), and Actinobacteria (16.87%). According to the values of AIC, Firmicutes was a microbial phylum that has high abundance in soil ecosystems influenced by pH covariates with AIC values of -6.54. Other soil covariates show less influence on Firmicutes with AIC values of -5.06. The combination model also show that pH cofactor was the important determinants with AIC values of -0.54 for Firmicutes (pH+C) and Firmicutes (pH+N) models. While AIC value for combination model of Firmicutes (C+N) only equals to 0.14.