Contrasting bacterial and archaeal distributions reflecting different geochemical processes in a sediment core from the Pearl River Estuary

Abstract

Microbial community structure and metabolic activities have profound impacts on biogeochemical processes in marine sediments. Functional bacteria such as nitrate-and sulfate-reducing bacteria respond to redox gradients by coupling specific reactions amenable to relevant energy metabolisms. However, similar functional patterns have not been observed for sedimentary archaea (except for anaerobic methanotrophs and methanogens). We coupled taxonomic composition with comprehensive geochemical species to investigate the participation of distinct bacteria and archaea in sedimentary geochemical cycles in a sediment core (300 cm) from Pearl River Estuary (PRE). Geochemical properties (NO 3 − , dissolved Mn and Fe, SO 4 2+ , NH 4 + ; dissolved inorganic carbon (DIC), δ 13 C DIC , dissolved organic carbon (DOC), total organic carbon (TOC), δ 13 C TOC , and fluorescent dissolved organic matter (FDOM)) exhibited strong depth variability of different trends. Bacterial 16S rRNA-and dsrB gene abundance decreased sharply with depth while archaeal and bathyarchaeotal 16S rRNA gene copies were relatively constant. This resulted in an increase in relative abundance of archaea from surface (11.6%) to bottom (42.8%). Network analysis showed that bacterial groups of Desulfobacterales, Syntrophobacterales and Gammaproteobacteria were significantly (P < 0.0001) associated with SO 4 2− and dissolved Mn while archaeal groups of Bathyarchaeota, Group C3 and Marine Benthic Group D (MBGD) showed close positive correlations (P < 0.0001) with NH 4 + , δ 13 C TOC values and humic-like FDOM. Our study suggested that these bacterial groups dominated in redox processes relevant to sulfate or metal oxides, while the archaeal groups are more like to degrade recalcitrant organic compounds in anaerobic sediments.

Vertical diversity and association pattern of total, abundant and rare microbial communities in deep‐sea sediments

“…Reconstruction of microbial networks can advance our knowledge of the complex behaviours in microbial communities and predict the effects of perturbations on community dynamics (Röttjers & Faust, 2018). Previous studies have used network analysis to explore interactions between marine benthic microbes and microbe–environment relationships (Buongiorno et al, 2019; Wang et al, 2020; Zhang, Li, et al, 2020), but most of these studies focused only on shallow sediments and none of them revealed the vertical shift of microbial networks in the subseafloor. In addition, network analysis can be a powerful tool for inferring the keystone taxa in a microbial community which can drive community composition and function irrespective of their abundance (Banerjee et al, 2018).…”

Vertical Stratification of Dissolved Organic Matter Linked to Distinct Microbial Communities in Subtropic Estuarine Sediments

“…Recent studies showed that CRAM organic matter such as benzoic acid and lignin were able to rapidly or slowly stimulate microbial growth (Liu S. et al, 2020). This was also supported by increased archaeal biomass especially Bathyarchaeia (Wang W. et al, 2020) and their correlations to O-rich molecules (Figure 4B).…”

“…Co-existence of highly unsaturated DOM molecules and Bathyarchaeia, Chloroflexi was also detected in subsurface sediments from Helgoland Mud Area ( Oni et al, 2015 ). Moreover, a significant correlation between archaea and humic-like fluorescent DOM (FDOM) was observed in our previous work ( Wang W. et al, 2020 ), indicating that archaea were potentially involved in sedimentary carbon transformation. While it is well known that DOM fuels the growth of microorganisms in sediments, specific interactions between microorganisms and DOM composition are poorly known.…”

Insights Into the Diversity of Terrestrial Soil Bacterial Communities Associated With Four Contrasting Köppen Climatic Zones.

“…Although soil comprises prokaryotes (bacteria, actinobacteria, cyanobacteria) and eukaryotes (fungi, microscopic algae, protozoans), bacteria are the most abundant among all of them and considered to be the pioneer colonizers [6][7][8]. Bacterial community inhabiting the soil contribute to soil structure formation, decompose organic matter and recalcitrant xenobiotics, help in plant growth promotion, modulate the global biogeochemical cycle and recycle nutrients as well as essential elements such as carbon, nitrogen, phosphorous, and sulphur [9][10][11][12][13][14][15][16]. The native bacterial community of the soil can originate directly from decomposed plant matter, whereas some others can enter accidentally through agricultural runoff and the digestive tract of animals to become the part of soil microbial community [17][18][19].…”