Bacterial Community Structure and Diversity of Closely Located Coastal Areas

Md Nurul Haider,Masahiko Nishimura,Kazuhiro Kogure

doi:10.4236/ojms.2016.63036

Abstract

Bacterial community structure and diversity of two closely located stations are usually considered similar which can be verified by more intensive investigations using relatively large amount of datasets from the next generation sequencer. This study was conducted to assess the bacterial community structure and diversity between two closely located coastal stations, the port side and the sea side of the Oarai, Ibaraki, Japan from March 2013 to July 2014 using 454 GS Junior sequencer. Two stations underwent similar changes in physicochemical properties but the community structure and diversity was different. The Proteobacteria (the class Alphaproteobacteria, followed by the Gammaproteobacteria) and the Bacteroidetes (the class Flavobacteriia) were two abundant phyla in both the stations. But, the Flavobacteriia was more abundant in the port side, contributed about 26% to 48%, compared to the sea side (about 12% to 39%). Conversely, the relative abundance of the Gammaproteobacteria was higher on the sea side, about 10% to 17%, compared to the port side (about 4% to 12%). Among others, the phyla Cyanobacteria, Deferribacteres, Verrucomicrobia and the class Betaproteobacteria were also relatively abundant at the sea side. Because of their dominancy, the class Flavobacteriia and Alphaproteobacteria were further analysed at a lower phylogenetic level and marked differences were observed between the stations. Bacterial biodiversity in terms of the species richness (Chao index) and evenness (inverse Simpson) indicated higher patterns of diversity in the sea side area compared to the port side. Non-metric Multidimensional Scaling fitting with the environmental features (metaMDS), redundancy analysis (RDA) and Bray-Curtis clustering analysis also showed marked differences in bacterial community structure and diversity between the stations. However, some OTUs were commonly found in both the stations in all the sampling periods. So, the bacterial community structure and diversity of the coastal areas are distinguishable even between two closely located sampling points.

Highlights

The community structures of bacteria are considered as one of the most fundamental information in microbial ecology as it provides basic information regarding the environment
The chlorophyll-a dataset with 4-km resolution was obtained from Level-3 MODerate resolution Imaging Spectroradiometer (MODIS) aqua standard–mapped image distributed by the National Aeronautics and Space Administration (NASA) Goddard
The chlorophyll-a values obtained from the satellite data were used to prepare chlorophyll-a illustrated maps (Figure 2) for each date of sampling using Ocean Data View (ODV) software

Summary

Introduction

The community structures of bacteria are considered as one of the most fundamental information in microbial ecology as it provides basic information regarding the environment. In common practice bacterial community structures are considered similar between two closely located areas of an aquatic environment and treated them as replicate to one another. The introduction of the generation sequencer [NGS] made it possible to obtain by a far large amount of sequencing data within a short period of time and showed the presence of numerous previously unknown sequences or operational taxonomic units (OTUs). These facilities allowed us to assess any similarity or dissimilarity even between two closely located areas at different times of the year

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Conclusion