Effects of increasing hydrostatic pressures on marine microbial enzymatic activities

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 15, 2025

Abstract High hydrostatic pressure is characteristic of the deep ocean and presumed to influence microbial functions viability. However, marine processes are typically measured only at atmospheric (0.1 MPa), limiting our understanding effects on activities microbes that sink as part biological carbon pump well those reside in ocean. To test functions, we extracellular enzymatic activities—the first step organic matter remineralization—of a moderate piezophile (Photobacterium profundum SS9), communities waters sediments from shallow abyssal (5,500 m) depths their cell-free enzymes (<0.2 µm). Activities were 0.1-100 MPa assess across nearly full range oceanic depths. P. SS9 show varying effects, considerable stimulation optimal (28 MPa) near complete inhibition (100 MPa). Pressure for diverse protein- carbohydrate-degrading phosphorus-acquiring among pelagic benthic communities. The most common effect partial activity reduction, indicating dampening initial remineralization increasing pressures. retention higher pressures was occasionally observed even surface-originating assemblages, functionality down hadal potential piezotolerance. These variable must be considered when quantifying degradation rates sinking deposited particulate

Language: Английский

Strong Effects of Increased Hydrostatic Pressure on Polysaccharide‐Hydrolyzing Enzyme Activities in Coastal Seawater and Sediments

Journal of Geophysical Research Biogeosciences, Journal Year: 2025, Volume and Issue: 130(2)

Published: Feb. 1, 2025

Abstract Heterotrophic microorganisms are responsible for transforming and respiring a substantial fraction of the organic matter produced by phytoplankton in surface ocean. Much this is composed polysaccharides, high‐molecular weight (HMW) sugars. To initiate degradation must produce extracellular enzymes right structural specificity to hydrolyze these complex structures. date, most measurements enzyme activities made at situ temperatures, but atmospheric pressure. However, previous studies have shown that hydrostatic pressure can impact functionality enzymes. Since deep sea communities may be seeded microbes from shallow waters, we aimed determine if affects performance coastal waters. extent which enzymatic microbial affected pressure, quantified seven polysaccharides under pressures ranging 0.1 MPa (atmospheric) 40 (equivalent 4,000 m). Enzyme pelagic were inhibited with increased while benthic more resistant Addition HMW resulted freely‐dissolved (<0.2 μm) strongly suggesting pressure‐resistant cell‐surface attached. Because inhibition varied polysaccharide, surmise complexity polysaccharide—and therefore number distinct required hydrolysis—is likely closely associated inhibition.

Language: Английский

Bioturbation in the hadal zone

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Feb. 18, 2025

The hadal zone, >6 km deep, remains one of the least understood ecosystems on Earth. We address bioturbational structures in sediment cores from depths exceeding 7.5 km, collected during IODP Expedition 386 Japan Trench. Micro-CT imaging 20 core sections allowed to identify biogenic sedimentary (incipient trace fossils) and their colonization successions within gravity flow deposits. Their frequency, consequent changes substrate consistency, oxygenation organic matter delivery remineralization controlled endobenthic colonization. gravity-flow beds show recurring bioturbation successions: initial is characterized by deposit-feeding such as Phycosiphon, Nereites Artichnus generating typically cm thick intensively bioturbated fabrics. final stage comprises slender spiral, lobate deeply penetrating straight ramifying burrow systems Gyrolithes, Pilichnus Trichichnus, interpreted include burrows microbe farming chemosymbiotic invertebrates. main factor precluding soupy substrate. Organic degradation post-event upward expansion anoxic zone drive change deposit feeding microbe-dependent strategies.

Language: Английский