Basin-scale seasonal changes in marine free-living bacterioplankton community in the Ofunato Bay

Abstract

The Ofunato Bay in the northeastern Pacific Ocean area of Japan possesses the highest biodiversity of marine organisms in the world and has attracted much attention due to its economic and environmental importance. We report here a shotgun metagenomic analysis of the year-round variation in free-living bacterioplankton collected across the entire length of the bay. Phylogenetic differences among spring, summer, autumn and winter bacterioplankton suggested that members of Proteobacteria tended to decrease at high water temperatures and increase at low temperatures. It was revealed that Candidatus Pelagibacter varied seasonally, reaching as much as 60% of all sequences at the genus level in the surface waters during winter. This increase was more evident in the deeper waters, where they reached up to 75%. The relative abundance of Planktomarina also rose during winter and fell during summer. A significant component of the winter bacterioplankton community was Archaea (mainly represented by Nitrosopumilus), as their relative abundance was very low during spring and summer but high during winter. In contrast, Actinobacteria and Cyanobacteria appeared to be higher in abundance during high-temperature periods. It was also revealed that Bacteroidetes constituted a significant component of the summer bacterioplankton community, being the second largest bacterial phylum detected in the Ofunato Bay. Its members, notably Polaribacter and Flavobacterium, were found to be high in abundance during spring and summer, particularly in the surface waters. Principal component analysis and hierarchal clustering analyses showed that the bacterial communities in the Ofunato Bay changed seasonally, likely caused by the levels of organic matter, which would be deeply mixed with surface runoff in the winter.

Seasonal and annual changes in the microbial communities of Ofunato Bay, Japan, based on metagenomics

“…Sample collection was performed according to Reza et al 32 . Briefly, approximately 8 L of seawater in Ofunato Bay, Iwate Prefecture, Japan, was collected monthly from 2015 to 2019 with a Van Dorn water sampler.…”

“…KSt. 2 was located in the oyster aquaculture field 32 .

Figure 1 Maps showing stations for seawater sample collection in Ofunato Bay, Iwate Prefecture, Japan.

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“…WGS sequencing was employed to determine nucleotide sequences of cells trapped on 0.2-μm filters according to Reza et al 32 . Briefly, the cells trapped on the filters were frozen, stored and subjected to DNA extraction after thawing using the Power Water isolation kit (MO BIO Laboratories Inc., Carlsbad, CA, USA), according to the manufacturer’s instructions at the Sanriku Coastal Education and Research Center.…”

Seasonal changes in the abundance of bacterial genes related to dimethylsulfoniopropionate catabolism in seawater from Ofunato Bay revealed by metagenomic analysis

“…Ofunato Bay, where surface water samples were collected from the three stations along its length to cover the entire bay. DNA was extracted through 0.2µm filters and sequenced, targeting all the microbes (Reza et al, 2018a) and the free-living bacterial fraction alone (Reza et al, 2018b). In this study, we focused on the bacterial genes associated with DMSP from the 0.2-µm filters.…”

Determinants of the Age at First Marriage among the University Teachers in Algeria: A mix Methodology Approach

“…Furthermore, and as an alternative, the Weibull model fits well the dataset (see Table 4) and this for Women sub-dataset, men sub-dataset and both of them; theoretically, researchers saw that parametric models in survival models are more robust than semi-parametric ones. To read more about the comparison between parametric and semi-parametric survival models see (Couallier, 2004;Reza et al, 2018).…”