Microbial Community Structure and Ecological Networks during Simulation of Diatom Sinking

Abstract

Microbial-mediated utilization of particulate organic matter (POM) during its downward transport from the surface to the deep ocean constitutes a critical component of the global ocean carbon cycle. However, it remains unclear as to how high hydrostatic pressure (HHP) and low temperature (LT) with the sinking particles affects community structure and network interactions of the particle-attached microorganisms (PAM) and those free-living microorganisms (FLM) in the surrounding water. In this study, we investigated microbial succession and network interactions in experiments simulating POM sinking in the ocean. Diatom-derived 13C- and 12C-labeled POM were used to incubate surface water microbial communities from the East China Sea (ECS) under pressure (temperature) of 0.1 (25 °C), 20 (4 °C), and 40 (4 °C) MPa (megapascal). Our results show that the diversity and species richness of the PAM and FLM communities decreased significantly with HHP and LT. Microbial community analysis indicated an increase in the relative abundance of Bacteroidetes at high pressure (40 MPa), mostly at the expense of Gammaproteobacteria, Alphaproteobacteria, and Gracilibacteria at atmospheric pressure. Hydrostatic pressure and temperature affected lifestyle preferences between particle-attached (PA) and free-living (FL) microbes. Ecological network analysis showed that HHP and LT enhanced microbial network interactions and resulted in higher vulnerability to networks of the PAM communities and more resilience of those of the FLM communities. Most interestingly, the PAM communities occupied most of the module hubs of the networks, whereas the FLM communities mainly served as connectors of the modules, suggesting their different ecological roles of the two groups of microbes. These results provided novel insights into how HHP and LT affected microbial community dynamics, ecological networks during POM sinking, and the implications for carbon cycling in the ocean.

Influence of Extremely High Pressure and Oxygen on Hydrocarbon-Enriched Microbial Communities in Sediments from the Challenger Deep, Mariana Trench

“…On the other hand, aerobic enrichments of SCAs or LCAs comprised 100 g of sediments, 20 mL of LMO medium supplemented with 120 μL of C 7 –C 17 mixture (or 0.12 g of C 18 –C 36 mixture), and 40 mL (25% of the total volume) of oxygenated-saturated Fluorinert TM (3M TM Corp., Minneapolis, MN, USA) [ 62 ] at 100 MPa and 4 °C for 150 days. All incubation components were placed in a sterile pouch (Kapak SealPak 500, 120 mL) and then sealed with a heat sealer.…”

A focus on different types of organic matter particles and their significance in the open ocean carbon cycle

“…Tamburini et al 2009;Maas et al 2020), formed in the lab using phytoplankton cultures (some of which with added minerals) often aggregated with roller tanks (e.g. Azam 1999, 2001;Passow et al 2003;Passow and De La Rocha 2006;Tamburini et al 2006Tamburini et al , 2021Le Moigne et al 2013;Riou et al 2018;Bižić-Ionescu et al 2018;Liu et al 2022), or artificial particles with homogenous composition and structures made for example from agar (e.g. Grossart et al 2003) or chitin (e.g.…”

“…Smith et al 1992;Azam 1999, 2001), microbial diversity (e.g. Bidle and Azam 2001;Grossart et al 2003;Tamburini et al 2006Tamburini et al , 2021Datta et al 2016;Riou et al 2018;Bižić-Ionescu et al 2018;Maas et al 2020;Liu et al 2022), or to study microbial interactions (e.g. Grossart et al 2003).…”

“…To study disaggregation processes a specific roller tank that combined rotating and oscillating action was used to generate diatom aggregates which were subsequently exposed to calibrated laminar shear (Song and Rau 2022). As the majority of the water column is under high pressure, some specific experimental setups are used to apply a pressure on particles (Tamburini et al 2006(Tamburini et al , 2009(Tamburini et al , 2021de Jesus Mendes et al 2007;Grossart and Gust 2009;Mendes and Thomsen 2012;Dong et al 2018;Stief et al 2021;Liu et al 2022). To mimic as closely as possible the in situ pressure and temperature variations experienced by sinking particles, Tamburini et al (2009) designed the "PASS" system.…”

Toward a Brighter Future: Enhanced Sustainable Methods for Preventing Algal Blooms and Improving Water Quality

“…POM particles have sedimentation coefficients that reflect their size and density, typically ranging from 1.1 to 1.6 g/cm 3 [51,52]. The adverse effects of excessive POM and harmful algal bloom (HAB) levels on nutrient cycling, pollution absorption, and biodiversity are discussed, along with the crucial role of POM removal in maintaining environmental and organismal health [23,[53][54][55][56][57].…”