Biology subjects

Agusti, S.

Publications and source records attributed to Agusti, S..

4 recordsLinked to original sources

bioRxiv2025

Red Sea Synechococcus exhibits greater resilience to UV-B radiation than pico-eukaryotic phytoplankton

1.UV-B radiation can be a significant stressor to primary producers in tropical seas, particularly to organisms residing close to the surface. We investigated the UV-B sensitivity of natural pico-phytoplankton communities in the Red Sea, one of the warmest seas on Earth. The communities were incubated either in full sunlight or under UV-B-reduction conditions. The mean lethal UV-B radiation dose (LRD50) of natural Synechococcus was 57 kJ to 73% non-detectable compared to 8 KJ to 45 % non-detectable for pico-eukaryotes. UV-B-induced Fv/Fm change ({Delta}Fv/Fm) in natural pico-phytoplankton communities ranged from -0.22 to 0.06 (mean: -0.08). Changes in Synechococcus growth under UV-B-reduction were more pronounced in cooler waters. The dominant pico-phytoplankton in the Red Sea, Synechococcus, exhibited a strong resistance to UV-B, highlighting their exceptional adaptation to the local conditions. Our results underscore the importance of considering the UV-B sensitivity of natural phytoplankton communities in the context of global change, which may differ from those of cultured strains.

ecology↗

bioRxiv2023

Marine picoplankton metagenomes from eleven vertical profiles obtained by the Malaspina Expedition in the tropical and subtropical oceans

The Ocean microbiome has a crucial role on Earths biogeochemical cycles, but also represents a tremendous potential for biological applications as part of the bluebiotechnology. During the last decade, global cruises such as Tara Oceans or the Malaspina Expedition have expanded our knowledge on the diversity and genetic repertoire of marine microbes. Nevertheless, there is still a gap of knowledge on broad scale patterns between photic and bathypelagic dark ocean microbes derived from the lack of detailed vertical profiles covering contrasting oceans depth regions. Here we present a dataset of 76 microbial metagenomes of the picoplankton size fraction (0.2-3.0 m) collected in 11 stations along the Malaspina Expedition circumnavigation that cover vertical profiles sampling at 7 depths, from the surface to the 4000 m deep (or the sea floor in shallower waters). This Malaspina Microbial Vertical Profiles metagenomes (MProfile) dataset produced 1.66 Tbp of raw DNA sequences that assembled into a total 25.3 Gbp. After gene prediction and annotation, we built a 46.3 million non-redundant gene compendium with their corresponding annotations (M-GeneDB-VP), clustered at 95% sequence similarity. This dataset will be a valuable resource for exploring the functional and taxonomic connectivity between the photic and bathypelagic tropical and subtropical ocean at a global scale, while increasing our general knowledge on the Ocean microbiome.

microbiology↗

bioRxiv2023

Global biogeography of the smallest plankton across ocean depths

Tiny ocean plankton (picoplankton) are fundamental for the functioning of the biosphere, but the ecological mechanisms shaping their biogeography are partially understood. Comprehending whether these microorganisms are structured by niche vs. neutral processes is highly relevant in the context of global change. The ecological drivers structuring picoplankton communities differ between prokaryotes and minute eukaryotes (picoeukaryotes) in the global surface ocean: while prokaryotic communities are shaped by a balanced combination of dispersal, selection, and drift, picoeukaryotic communities are mainly shaped by dispersal limitation. Yet, whether or not the relative importance of these processes in structuring picoplankton varies as we dive into the deep ocean was unknown. Here we investigate the mechanisms structuring picoplanktonic communities inhabiting different ocean depths. We analyzed 451 samples from the tropical and subtropical global ocean and the Mediterranean Sea covering the epi- (0-200m), meso- (200- 1,000m), and bathypelagic (1,000-4,000m) depth zones. We found that selection decreased with depth possibly due to lower habitat heterogeneity. In turn, dispersal limitation increased with depth, possibly due to dispersal barriers such as water masses and bottom topography. Picoplankton {beta}-diversity positively correlated with environmental heterogeneity and water mass variability in both the open-ocean and the Mediterranean Sea. However, this relationship tended to be weaker for picoeukaryotes than for prokaryotes. Community patterns were generally more pronounced in the Mediterranean Sea, probably because of its substantial cross-basin environmental heterogeneity and deep-water isolation. Altogether, we found that different combinations of ecological mechanisms shape the biogeography of the smallest members of the ocean microbiome across ocean depths.

ecology↗

bioRxiv2019

Metabolic Architecture of the Deep Ocean Microbiome

The deep sea, the largest compartment of the ocean, is an essential component of the Earth system, but the functional exploration of its microbial communities lags far behind that of other marine realms. Here we analyze 58 bathypelagic microbial metagenomes from the Atlantic, Indian, and Pacific Oceans in an unprecedented sampling effort from the Malaspina Global Expedition, to resolve the metabolic architecture of the deep ocean microbiome. The Malaspina Deep-Sea Gene Collection, 71% of which consists of novel genes, reveals a strong dichotomy between the functional traits of free-living and particle-attached microorganisms, and shows relatively patchy composition challenging the paradigm of a uniform dark ocean ecosystem. Metagenome Assembled Genomes uncovered 11 potential new phyla, establishing references for deep ocean microbial taxa, and revealed mixotrophy to be a widespread trophic strategy in the deep ocean. These results expand our understanding of the functional diversity, metabolic versatility, and carbon cycling in the largest ecosystem on Earth.\n\nOne Sentence SummaryA whole community genomic survey of the deep microbiome sheds light on the microbial and functional diversity of the dark ocean.

microbiology↗