English

A Olapade Ola

doi:10.5897/ajmr2020.9389

Abstract

The spatial distribution and diversity within bacterioplankton assemblages in four coastal sites along the southern points of the Atlantic Ocean were examined using the Illumina high-throughput that targets 16S rRNA genes to examine indigenous bacterial assemblages in the littoral zones along the coast of the ocean. Results of the study showed very similar bacterial representation between the coastal sites with majority of the sequences affiliated with members of the Proteobacteria (52 to 59%), Bacteriodetes (21 to 31%) followed by Actinobacteria (3 to 9.5%) and Planctomycetes (2.1 to 4.5%). The bacterioplankton assemblages at each site examined were quite diverse, with members of the Gammaproteobacteria found as the most abundant bacterial class among the four sites. However, clear differences were observed among the sites at the order level, with the Chromatiales the more dominant in the eastern coastal (CPTI) sites, while clades belonging to the Flavobacteriales and Rhodobacterales were more prevalent in the two western (CPTA) coastal sites. While the results of unweighted pair group method with arithmethic (UPGMA) clustering and principle coordinate (PCoA) revealed two spatially separate clusters among sites, canonical correspondence (CCA) analysis indicated that environmental variables such as temperature, pH and conductivity were probably the major influencers of bacterial occurrences at the coastal sites. Key words: Bacterioplankton assemblages, ocean, 16S rRNA gene sequencing.

Highlights

The bacterioplankton assemblages in oceans have been described as comprising one of the largest and active microbial assemblages in the biosphere (Whitman et al.,1998; Salazar and Sunagawa, 2017), where they actively partake in the biogeochemical influxes and cycling of various nutrients and organic compounds (Azam and Malfatti, 2007; Falkowski et al, 2008, Zehr and Kudela, 2011)
The 16S rRNA gene sequences obtained from 4 different coastal locations along the southernmost parts of the Atlantic Ocean in Cape Town, South Africa were analyzed in order to characterize the bacterial community structures in response to potential changes in environmental variables between these spatially different coastal marine sites
The numerical dominance of members of the Proteobacteria and Bacteroidetes as observed in this study is consistent with previous studies that have reported the high occurrences of these two bacterial phyla in various marine systems (Brown et al, 2009; Seo et al, 2017; Wang et al, 2018; Wu et al, 2019)

Summary

Introduction

The bacterioplankton assemblages in oceans have been described as comprising one of the largest and active microbial assemblages in the biosphere (Whitman et al.,1998; Salazar and Sunagawa, 2017), where they actively partake in the biogeochemical influxes and cycling of various nutrients and organic compounds (Azam and Malfatti, 2007; Falkowski et al, 2008, Zehr and Kudela, 2011). Contrasting findings have been previously reported regarding bacterial diversity and biogeographic distributions in marine systems, especially in tropical oceans (Pommier et al, 2007; Fuhrman et al, 2008; Milici et al, 2016).

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