The differentiation of iron-reducing bacterial community and iron-reduction activity between riverine and marine sediments in the Yellow River estuary

Abstract

Rivers are the primary contributors of iron and other elements to the global oceans. Iron-reducing bacteria play an important biogeochemical role in coupling the iron and carbon redox cycles. However, the extent of changes in community structures and iron-reduction activities of iron-reducing bacteria in riverine and coastal marine sediments remains unclear. This study presents information on the spatial patterns and relative abundance of iron-reducing bacteria in sediments of the Yellow River estuary and the adjacent Bohai Sea. High-throughput sequencing of bacterial 16S rRNA found that the highest relative abundances and diversities were from the estuary (Yellow River-Bohai Sea mixing zone). Pseudomonas, Thiobacillus, Geobacter, Rhodoferax, and Clostridium were the most abundant putative iron-reducing bacteria genera in the sediments of the Yellow River. Vibrio, Shewanella, and Thiobacillus were the most abundant in the sediments of the Bohai Sea. The putative iron-reducing bacterial community was positively correlated with the concentrations of total nitrogen and ammonium in coastal marine sediments, and was significantly correlated with the concentration of nitrate in river sediments. The riverine sediments, with a more diverse iron-reducing bacterial community, exhibited increased activity of Fe(III) reduction in enrichment cultures. The estuary-wide high abundance of putative iron-reducing bacteria suggests that the effect of river-sea interaction on bacterial distribution patterns is high. The results of this study will help the understanding of the biogeochemical cycling of iron in riverine and coastal marine environments. Keywords Iron-reducing bacteria • River • Coastal sea • River-sea interaction Edited by Chengchao Chen.

Effects of tidal influence on the structure and function of prokaryotic communities in the sediments of a pristine Brazilian mangrove

“…However, Firmicutes were also found at elevated levels at several anthropogenically impacted sites (Torres et al, 2019;Haldar and Nazareth, 2018;Tiralerdpanich et al, 2018). While it could be that their presence is due to the pristine nature of the area, it may also be due to the local climate (Nogueira et al, 2015), an unmeasured environmental factor (Tong et al, 2019), or the presence of another organism such as a non-prokaryote or prokaryote which is difficult to detect using 16S rRNA gene amplicon sequencing (Eloe-Fadrosh et al, 2016;Zhang et al, 2021).…”

“…The results show that both salinity and organic matter were significantly correlated with communities in different tidal zones, confirming the hypothesis that changes in physicochemical parameters lead to changes in the prokaryotic communities inhabiting these sediments. It has been previously observed that tidal variations can cause nutrient washout or erosion (Behera et al, 2019;Zhang et al, 2020), which in turn can change the bioavailability patterns for organic matter and essential nutrients along the distinct tidal zones of a mangrove habitat. Salinity levels are also influenced by the tidal variations, and it has been previously determined that the increased salinity as well as the prevalence of humic-like substances can interfere with the accessibility of the microbial community to the sediment organic matter (Wang et al, 2010;Ceccon et al, 2019).…”

“…It is also important to notice that the use of 16S rRNA gene amplicons potentially impairs the identification of some important prokaryotic groups, especially from the domain Archaea, which in some environments can reach 10 % of the total microbial community (Eloe-Fadrosh et al, 2016). Recent research has emphasized how the use of 16S rRNA gene amplicon sequencing can lead to failure in detecting some archaeal populations which can play important roles in nutrient cycling (Zhang et al, 2021). Taken together, however, this work suggests that a variety of environmental factors, potentially driven by tidal cycles, can generate niche variations that influence the structure and function of communities.…”

“…It is important to note that these functional profiles are not the result of metagenomic sequencing; as such it is not necessarily true that all members of the taxa have the same genome as the reference holotype, nor is it necessarily true that these genes would be expressed equally, even if present, and this should best be understood as a measure of potential metabolic activity. Studies that have performed functional profiling using metagenome sequencing on mangrove sediments resulted in comparatively greater resolution (Zhang et al, 2021), although the use of 16S rRNA gene sequencing has been proved to provide comparable results for the recovery of general patterns of pathway abundances (Jovel et al, 2016).…”

Environmental Parameters and Substrate Type Drive Microeukaryotic Community Structure During Short-Term Experimental Colonization in Subtropical Eutrophic Freshwaters

“…There could be several explanations for this. In the river, environmental factors and water flow direction differed daily at low and high tide ( Table 2), resulting in diverse environmental stresses on the microbial communities (Böer et al, 2009;Zhang et al, 2020). Changing tides can affect biotic factors such as source communities and species interaction.…”