Microbial community composition of the Danshui River estuary of Northern Taiwan and the practicality of the phylogenetic method in microbial barcoding

In this study, the microbial community in a mangrove ecosystem was surveyed and used to test the eligibility of 16S rDNA library and neighbor-joining method for the purpose of estimating microbial composition. Genetic diversity (π) and four other diversity indices (Simpson's unbiased, Shannon-Wiener, Evenness, and Chao1 indices) were applied to estimate the adaptive lineages of microorganisms in the mangrove ecosystem. The results indicated that γ-Proteobacteria is the most diverse taxon, while the most abundant family is Rhodobacteraceae (α-Proteobacteria), followed by Comamonadaceae (β-Proteobacteria). This result may imply the existence of a graded distribution of microbial diversity across a spectrum of different salinities in the waterbody of this estuary ecosystem. Furthermore, at least 500-1,000 bps of the posterior portion of 16S rDNA is required as a marker to profile the microbial diversity in a microcosm of interest using phylogenetic methods, according to the results of our sliding window analyses for the measurements of π, consistency index, and retention index.