Biology subjects

Antler, G.

Publications and source records attributed to Antler, G..

3 recordsLinked to original sources

bioRxiv2026

Divergent methane production and microbial community responses to carbon enrichment in freshwater wetland sediments

Methane (CH4) accumulation in wetland sediments reflects interactions among organic matter, sediment chemistry, and microbial communities. We combined depth-resolved field characterization across four wetland habitats in northern Israel with complementary incubations to examine methane accumulation and responses to labile-carbon enrichment. Sediment cores were characterized using Rock-Eval analysis, porewater chemistry, oxygen profiling at three sites, and mcrA amplicon sequencing. High CH4 concentrations occurred under contrasting conditions: Ein Nimfit (EN) contained approximately 12% total organic carbon and reached 2.1 mM CH4, whereas Ein Afek site EA2 contained approximately 5% carbon and accumulated 0.7-1.7 mM CH4. Both showed sulfate depletion, but EN exhibited pronounced sulfide accumulation, whereas EA2 showed greater dissolved iron and nutrient enrichment. Their classified methanogenic assemblages also differed. EA1 remained methane poor despite increasing carbon content with depth, while EA3 combined low carbon content and CH4 accumulation with detectable methanogens and lower methanogenic diversity. In a 36-day bottle experiments using sediments from two of the four wetland habitats, sucrose-amended EA3 exhibited a transient maximum of 18.8 mmol collected CH4 kg-1 wet sediment during Days 22-29, whereas EN reached its highest collected amount during Days 29-36. Methane proportions increased before the large output increase in EA3 but remained comparatively stable and high in EN. Soluble chemical oxygen demand trajectories and microbial community changes also differed. These findings identify distinct biogeochemical settings supporting methane accumulation and demonstrate methanogenic potential in low-CH4 sediment, emphasizing the complementary information provided by field profiles, microbial characterization, and exploratory enrichment experiments.

microbiology↗

bioRxiv2023

Active microbial communities facilitate carbon turnover in brine pools found in the deep Southeastern Mediterranean Sea

Discharge of gas-rich brines fuels productive chemosynthetic ecosystems in the deep sea. In these salty, methanic and sulfidic brines, microbial communities adapt to specific niches along the physicochemical gradients. However, the molecular mechanisms that underpin these adaptations are not fully known. Using metagenomics, we investigated the dense ([~]106 cell ml-1) microbial communities that occupy small deep-sea brine pools found in the Southeastern Mediterranean Sea (1150 m water depth, [~]22{degrees}C, [~]60 PSU salinity, sulfide, methane, ammonia reaching millimolar levels, and oxygen usually depleted), reaching high productivity rates of 685 {micro}g C L-1 d-1 ex-situ. We curated 266 metagenome-assembled genomes of bacteria and archaea from the several pools and adjacent sediment-water interface, highlighting the dominance of a single Sulfurimonas, which likely fuels its autotrophy using sulfide oxidation or inorganic sulfur disproportionation. This lineage may be dominant in its niche due to genome streamlining, limiting its metabolic repertoire, particularly by using a single variant of sulfide: quinone oxidoreductase. These primary producers co-exist with ANME-2c archaea that catalyze the anaerobic oxidation of methane. Other lineages can degrade the necromass aerobically (Halomonas and Alcanivorax), or anaerobically through fermentation of macromolecules (e.g., Caldatribacteriota, Bipolaricaulia, Chloroflexota, etc). These low-abundance organisms likely support the autotrophs, providing energy-rich H2, and vital organics such as vitamin B12.

microbiology↗

bioRxiv2023

Emiliania huxleyi virus arrests host calcification and nutrient consumption, and triggers shifts in organic stoichiometry

Blooms of the coccolithophore Emiliania huxleyi are routinely infected by a specific lytic virus (EhV), which rapidly kills host cells triggering bloom termination and organic and inorganic carbon export. However, the impact of EhV on the dynamic of resource acquisition and cellular stoichiometry remains unknown, limiting the current understanding of the ecological and biogeochemical significance of E. huxleyi blooms. To tackle this knowledge gap, we used algal and EhV cultures to determine over the course of infections the dynamics of alkalinity, modulated by calcification, nitrate and phosphate consumption and organic matter stoichiometry. We found that within 24hr alkalinity concentration stabilized and nutrient uptake declined to background levels. In parallel, the stoichiometric ratio of carbon to nitrogen was about 15% higher and the nitrogen to phosphorus ratio was about 12% lower during infections relative to controls. These variations likely resulted from lipid accumulation required for viral replication and the differential retention of phosphorus-rich macromolecular pools in decaying cells, respectively. Finally, after host population decay a progressive enrichment in phosphorus relative to nitrogen and carbon was detected in the remaining cell lysates. We estimate that this stoichiometric shift post-infection was driven by the progressive accumulation of heterotrophic bacteria involved in the degradation of organic material. Viral-mediated cell remodeling and consequent shifts in biomass stoichiometry likely impacts the patterns of nutrient cycling and biological carbon pump efficiency during large-scale blooms in the oceans.

microbiology↗