Abstract
Bacteria are highly diverse and ubiquitous organisms that play a key role as drivers for ecosystem processes. The application of NGS (next-generation sequencing technologies) for 16S analysis has been broadly used for understanding bacterioplankton composition and structure. Most of studies conducted on aquatic ecosystems with 16S NGS have been in seawater and lakes. A few studies using NGS have been conducted in river environments and have suggested the presence of a bacterial seed-bank. We performed 16S highly variable V4 region high-throughput analysis in the Sinos River, which is located in one of most important Brazilian industrial centers. This region has several contrasts in its environmental characteristics, presenting a longitudinal gradient of eutrophication and making it a remarkable study site for observing the dynamics of bacterioplankton. We demonstrated consistent evidence for the existence of a bacterial seed-bank and its longitudinal persistence. Seasonal shifts reinforce the importance of the source of the river in maintaining the bacterial seed-bank that spreads throughout the river. Therefore, the preservation of the source of the river is important not only for hydrologic reasons but also to maintain the microbial composition and the ecological integrity of the river.
Highlights
The large domain of prokaryotic organisms encompassing the microbiome is highly diverse and ubiquitous, playing key roles as drivers of the major ecosystem processes [1]
The Sinos River microbiome samples were categorized into four different groups, based on the following environmental data (Table 1): i) Location, the collecting sites of the samples; ii) Course, the course sections of the river; iii) PhyChem, groups of physicochemical features; and iv) Season, the season in which the samples were collected
Through sequencing barcoded amplicons from the 16S V4 region in the MiSeq Illumina platform, we generated a total of 5,790,065 pair-end reads for the 28 samples, which passed through rigorous quality control, classification through the OTU open reference picking process and OTU represented by less than 5 reads was discarded (S1 Table). This analysis resulted in 53,624 OTUs, which 35,850 OTUs (66.9%) were found in at least one sample from each season, representing 94.6% of all classified reads (Fig. 2A). These results strongly suggest that the bacterioplankton of the Sinos River are highly homogeneous in composition, exhibiting a seedbank of bacteria in the river source (S01 and W01)
Summary
The large domain of prokaryotic organisms encompassing the microbiome is highly diverse and ubiquitous, playing key roles as drivers of the major ecosystem processes [1]. The application of NGS to 16S analysis has changed the sensitivity and throughput of microbiological analysis and has been widely used for understanding bacterioplankton [2,3]. The most studied aquatic ecosystem, some recent studies have described several patterns of bacterial diversity [4,5,6]. Seasonal and environmental changes can affect bacterioplankton community structures [7]. Studies from lakes and streams represent the majority of knowledge of freshwater bacterioplankton. These studies have been important for understanding the structure, composition and dynamics of microbial diversity [10,11,12,13] as well as microbial responses to environmental disturbances [14,15]
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