Search

Art i ciència són dues disciplines humanes aparentment oposades en gairebé tot. L'art és suposadament intuïtiu, espiritual, inútil per a les coses pràctiques, i no té caducitat entre altres propietats. La ciència, per contra, és suposadament deductiva, racional, pràctica i està sent constantment reformada. Davant d'un quadre abstracte el públic es demana "què significa?" i potser "això ho pot fer un nen". Davant d'un descobriment científic la pregunta més freqüent és "per a què serveix?" En realitat, caldria demanar-se què signifiquen els descobriments científics? I per a què serveix una obra d'art? Ambdues disciplines comparteixen moltes coses. Els mètodes per arribar a un quadre magistral com "Les senyoretes d'Avinyó" té molts paral·lelismes amb la descoberta de l'estructura de l'ADN.

It is well known that only a small fraction of the marine microbial diversity, which mainly belong to the so-called rare biosphere, can be retrieved by isolation. However, this paradigm has not been fully tested at a broad scale, especially in the deep ocean and in the ocean particle microbiome. Here, we compared 16S rRNA gene sequences from a large collection (>2000) of cultured heterotrophic marine bacteria with global 16S rRNA metabarcoding (16S Tags) datasets covering surface, mesopelagic and bathypelagic ocean samples that included 16 of the 22 samples used for isolation. These global datasets represent 60.322 unique 16S amplicon sequence variants (ASVs). Our results reveal a significantly higher proportion of isolates identical to ASVs in deeper ocean layers, which included the isolation of 3 of the top 10 most abundant 16S ASVs in the global bathypelagic ocean, related to the genera Sulfitobacter, Halomonas and Erythrobacter. These isolates contributed differently to the prokaryotic communities across different plankton size fractions, recruiting between 38% in the free-living fraction (0.2 -0.8 ¿m) and up to 45% in the largest particles (20-200 ¿m) in the bathypelagic ocean. Our findings support the hypothesis that sinking particles in the bathypelagic act as resource-rich habitats, suitable for the growth of heterotrophic bacteria with a copiotroph lifestyle that can be cultured, and that these cultivable bacteria can also thrive as free-living bacteria

Traditional culture techniques usually retrieve a small fraction of the marine microbial diversity, which mainly belong to the so-called rare biosphere. However, this paradigm has not been fully tested at a broad scale, especially in the deep ocean. Here, we examined the fraction of heterotrophic bacterial communities in photic and deep ocean layers that could be recovered by culture-dependent techniques at a large scale. We compared 16S rRNA gene sequences from a collection of 2003 cultured heterotrophic marine bacteria with global 16S rRNA metabarcoding datasets (16S TAGs) covering surface, mesopelagic and bathypelagic ocean samples that included 16 of the 23 samples used for isolation. These global datasets represent 60 322 unique 16S amplicon sequence variants (ASVs). Our results reveal a significantly higher proportion of isolates identical to ASVs in deeper ocean layers reaching up to 28% of the 16S TAGs of the bathypelagic microbial communities, which included the isolation of 3 of the top 10 most abundant 16S ASVs in the global bathypelagic ocean, related to the genera Sulfitobacter, Halomonas and Erythrobacter. These isolates contributed differently to the prokaryotic communities across different plankton size fractions, recruiting between 38% in the free-living fraction (0.2–0.8 µm) and up to 45% in the largest particles (20–200 µm) in the bathypelagic ocean. Our findings support the hypothesis that sinking particles in the bathypelagic act as resource-rich habitats, suitable for the growth of heterotrophic bacteria with a copiotroph lifestyle that can be cultured, and that these cultivable bacteria can also thrive as free-living bacteria

Environmental conditions change dramatically from winter to summer in the Arctic Ocean. As the sea ice melts, large amounts of algal polysaccharides are released in the water column while simultaneously the main phytoplankton bloom develops beneath the ice. These changes are reflected in the taxonomic composition of the heterotrophic bacterioplankton within the upper water column. The dominant taxonomic groups in winter are Alpha- and Gammaproteobacteria and Thaumarcheota. In contrast, Bacteroidetes and Gammaproteobacteria are instead dominant during the spring-summer bloom period. Here we present a time series from early March to late July in Dease Strait (Canadian Arctic) where metagenomes and metatranscriptomes from the planktonic bacterial size fraction were obtained over a spring ice algal bloom to investigate the causes of this transition in microbial community composition. Looking at the genes present and expressed, two main traits seemed to allow Bacteroidetes to dominate. First, they had a large collection of polysaccharide degradation genes. In March, on the other hand, glycosyl-hydrolases degraded a variety of compounds including fucoidan, a cell wall polysaccharide of diatoms. During the bloom, on the other hand, glycosyl-hydrolases for laminarin, a storage polysaccharide of diatoms, became extremely abundant. Thus, Bacteroidetes were in the optimal position to take advantage from the diatom polysaccharides and had transporters to incorporate iron siderophore complexes. However, they did not show genes for the synthesis of siderophores (Puente-Sánchez et al. 2022). This task was carried out almost exclusively by Gammaproteobacteria. Clearly, the ability to steal iron from other bacteria and to use algal polysaccharides are two traits favouring the dominance of this phylum in summer

Des de fa milers d'anys, l'ésser humà fa servir multitud de mètodes per conservar els aliments: refrigerats, congelats, assecats, deshidratats, liofilitzats, salats, curats, adobats, marinats, pasteuritzats, esterilitzats, enllaunats, fermentats, etc. La idea era transformar els nostres aliments en ambients tan extrems que no fos possible la vida ni tan sols per als microorganismes més resistents. El que no era reconegut, però, és que algunes d'aquestes tècniques també preserven els microorganismes, cosa que els permet romandre inactius (però vius) durant períodes de temps molt llargs. En alguns casos, això permet que els microbis viatgin en el temps, sens dubte per desenes de milers d'anys i potser fins i tot per milions d'anys. I això ha estat succeint des de l'origen de la vida com a procés natural. Així, la microbiota contemporània és un compost de microorganismes moderns i representants del passat

The ocean is the largest ecosystem in the Planet. But due to its size and depth, our understanding of the microbiome is still rudimentary. We can count how many microorganisms live in it and we can measure some of their activities. But we only have crude estimates of how many species do they belong to. The microbiome includes a few abundant taxa that carry out most ecosystem functions and a very long list of rare taxa that provide a formidable richness of genes and potential. Microbes can easily disperse globally and, intriguingly, they can also travel in time. Even though we have an emerging picture, the possibility of engineering the ocean microbiome is still very remote

[EN] Marine phytoplankton, including cyanobacteria and microalgae, dominates primary production across two thirds of the earth’s surface, sustaining virtually all marine life and exerting a fundamental control over global climate through carbon sequestration into the deep ocean. These unicellular photoautotrophs are responsible for roughly 50% of global net primary production, which is equivalent to producing 50 gigatons of organic carbon (C) per year (about 140 million t per day). […], [ES] El fitoplancton marino, que incluye tanto a las cianobacterias como a las microalgas, domina la producción primaria en dos tercios de la superficie de la Tierra, sustentando prácticamente toda la vida marina y ejerciendo un control fundamental sobre el clima global mediante el secuestro de carbono en las profundidades del océano. Estos productores primarios unicelulares son responsables de aproximadamente el 50% de la producción primaria neta mundial, lo que equivale a producir 50 gigatoneladas de carbono orgánico (C) al año (alrededor de 140 millones de toneladas al día). […], [CAT] El fitoplàncton marí, que inclou tant als cianobacteris com a les microalgues, domina la producció primària en dos terços de la superfície de la Terra, sustentant pràcticament tota la vida marina i exercint un control fonamental sobre el clima global mitjançant el segrest de carboni en les profunditats de l’oceà. Aquests productors primaris unicel·lulars són responsables d’aproximadament el 50% de la producció primària neta mundial, la qual cosa equival a produir 50 gigatones de carboni orgànic (C) l’any (al voltant de 140 milions de tones al dia). […]