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Current -omics methods allow the collection of a large amount of information that helps in describing the microbial diversity in nature. Here, and as a result of a culturomic approach that rendered the collection of thousands of isolates from 5 different hypersaline sites (in Spain, USA and New Zealand), we obtained 21 strains that represent two new Salinibacter species. For these species we propose the names Salinibacter pepae sp. nov. and Salinibacter grassmerensis sp. nov. (showing average nucleotide identity (ANI) values < 95.09% and 87.08% with Sal. ruber M31T, respectively). Metabolomics revealed species-specific discriminative profiles. Sal. ruber strains were distinguished by a higher percentage of polyunsaturated fatty acids and specific N-functionalized fatty acids; and Sal. altiplanensis was distinguished by an increased number of glycosylated molecules. Based on sequence characteristics and inferred phenotype of metagenome-assembled genomes (MAGs), we describe two new members of the genus Salinibacter. These species dominated in different sites and always coexisted with Sal. ruber and Sal. pepae. Based on the MAGs from three Argentinian lakes in the Pampa region of Argentina and the MAG of the Romanian lake Fără Fund, we describe the species Salinibacter pampae sp. nov. and Salinibacter abyssi sp. nov. respectively (showing ANI values 90.94% and 91.48% with Sal. ruber M31T, respectively). Sal. grassmerensis sp. nov. name was formed according to the rules of the International Code for Nomenclature of Prokaryotes (ICNP), and Sal. pepae, Sal. pampae sp. nov. and Sal. abyssi sp. nov. are proposed following the rules of the newly published Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode). This work constitutes an example on how classification under ICNP and SeqCode can coexist, and how the official naming a cultivated organism for which the deposit in public repositories is difficult finds an intermediate solution.

Positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and H-1 NMR revealed major compositional and structural changes of dissolved organic matter (DOM) after mixing two sets of river waters in Amazon confluences: the Solimoes and Negro Rivers (S + N) and the Amazon and Tapajo s Rivers (A + T). We also studied the effects of water mixing ratios and incubation time on the composition and structure of DOM molecules. NMR spectra demonstrated large-scale structural transformations in the case of S + N mixing, with gain of pure and functionalized aliphatic units and loss of all other structures after 1d incubation. A + T mixing resulted in comparatively minor structural alterations, with a major gain of small aliphatic biomolecular binding motifs. Remarkably, structural alterations from mixing to 1d incubation were in essence reversed from 1d to 5d incubation for both S + N and A + T mixing experiments. Heterotrophic bacterial production (HBP) in endmembers S, N, and S + N mixtures remained near 0.03 mu gC L-1 h(-1), whereas HBP in A, T, and A + T were about five times higher. High rates of dark carbon fixation took place at S + N mixing in particular. In-depth biogeochemical characterization revealed major distinctions between DOM biogeochemical changes and temporal evolution at these key confluence sites within the Amazon basin., Funding Agencies|Alexander von Humboldt Foundation; Swedish Research Council for Sustainable Development, FORMAS [2021-02429]; Swedish Research Council [2012-00048]; European Research Council ERC [725546]; Chinese Scholarship Council [201806360268]; CAPES; FAPERJ (Cientista do Nosso Estado); CNPq (Universal and Ciencias sem Fronteiras)

Potentially harmful disinfection by-products (DBPs) are formed upon drinking water treatment when disinfectantsreact with organic matter in the water. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) provides information on the compositions of individual DBPs in the unknown, toxicologically relevantfraction, comprising non-volatile, high-molecular weight DBPs. This review evaluates current applications of FTICR-MS for DBP analysis to assist improved analysis with this technique. Four methodological aspects are infocus, 1) The use of quenching agents, 2) The choice of extraction method 3) The choice of ionization techniques/modes, and 4) Data processing including DBP formula verification and interpretation. Quenching can lead todecomposition or adduct formation and needs to be further evaluated or avoided. There is a large potential toexpand FT-ICR-MS DBP analysis by applying different SPE sorbents and ionization techniques, and improvedsystematic verification procedures are important to ensure reliable non-target analysis., Funding: Swedish Research Council for Sus-tainable Development, FORMAS [2021-01662]

Rivers are natural biogeochemical systems shaping the fates of dissolved organic matter (DOM) from leaving soils to reaching the oceans. This study focuses on Amazon basin DOM processing employing negative and positive electro-spray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI[+/-] FT-ICR MS) and nuclear mag-netic resonance spectroscopy (NMR) to reveal effects of major processes on the compositional space and structural characteristics of black, white and clear water systems. These include non-conservative mixing at the confluences of (1) Solimoes and the Negro River, (2) the Amazon River and the Madeira River, and (3) in-stream processing of Amazon River DOM between the Madeira River and the Tapajos River. The Negro River (black water) supplies more highly oxygenated and high molecular weight compounds, whereas the Solimoes and Madeira Rivers (white water) contribute more CHNO and CHOS molecules to the Amazon River main stem. Aliphatic CHO and abundant CHNO compounds prevail in Tapajos River DOM (clear water), likely originating from primary production. Sorption onto particles and heterotrophic microbial degradation are probably the principal mechanisms for the observed changes in DOM composition in the Amazon River and its tributaries., Funding Agencies|Alexander von Humboldt Foundation; Swedish Research Council for Sustainable Development, FORMAS [2013-01077, 2021-0242]; Swedish Research Council (VR) [2012-00048]; European Research Council ERC [725546]; China Scholarship Council [201806360268]; Brazilian Foundation CAPES; Brazilian Foundation FAPERJ; Brazilian Foundation CNPq

Dissolved organic matter (DOM) remineralization is limited to a greater or lesser degree at different layers in the ocean. In order to investigate the key abiotic and biotic factors that may enhance DOC remineralization in the deep ocean, we studied the changes in function and structure of deep prokaryotic communities after additions of the same amount of dissolved organic compounds with different quality. We performed experiments with deep sea prokaryotic assemblages subjected to four different treatments: CL (addition of labile DOC), CM (addition of a mix of organic compounds with different lability) and CR (addition of recalcitrant humic acids) and K (control). Prokaryotic biomass markedly increased when the labile compounds or the diverse chemical mixture were added (CL and CM treatments), whereas the prokaryotic response was lower under either the control K or CR treatments. Accordingly, we found lower activity and similar patterns of extracellular enzymatic activities in CR and K compared to CL and CM treatments. In all treatments a decrease in prokaryotic richness consistently occurred along the incubations, but interestingly, the decrease was lower in the control and in the CR treatments. Our results indicate that the chemical diversity of organic matter is a key factor determining microbial structure and activity in the deep ocean

Current -omics methods allow the collection of a large amount of information that helps in describing the microbial diversity in nature. Here, and as a result of a culturomic approach that rendered the collection of thousands of isolates from 5 different hypersaline sites (in Spain, USA and New Zealand), we obtained 21 strains that represent two new Salinibacter species. For these species we propose the names Salinibacter pepae sp. nov. and Salinibacter grassmerensis sp. nov. (showing average nucleotide identity (ANI) values < 95.09% and 87.08% with Sal. ruber M31T, respectively). Metabolomics revealed species-specific discriminative profiles. Sal. ruber strains were distinguished by a higher percentage of polyunsaturated fatty acids and specific N-functionalized fatty acids; and Sal. altiplanensis was distinguished by an increased number of glycosylated molecules. Based on sequence characteristics and inferred phenotype of metagenome-assembled genomes (MAGs), we describe two new members of the genus Salinibacter. These species dominated in different sites and always coexisted with Sal. ruber and Sal. pepae. Based on the MAGs from three Argentinian lakes in the Pampa region of Argentina and the MAG of the Romanian lake Fără Fund, we describe the species Salinibacter pampae sp. nov. and Salinibacter abyssi sp. nov. respectively (showing ANI values 90.94% and 91.48% with Sal. ruber M31T, respectively). Sal. grassmerensis sp. nov. name was formed according to the rules of the International Code for Nomenclature of Prokaryotes (ICNP), and Sal. pepae, Sal. pampae sp. nov. and Sal. abyssi sp. nov. are proposed following the rules of the newly published Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode). This work constitutes an example on how classification under ICNP and SeqCode can coexist, and how the official naming a cultivated organism for which the deposit in public repositories is difficult finds an intermediate solution.

Figure S1. Geographical distribution of the six locations studied here and their inter-location distances (given in the table). The distances given in each location refer to Mallorca. The hypersaline here are: Mallorca (Es Trenc and S’Avall and separated by 3.5 km) and Santa Pola in Spain, Fără Fund in Romania, Great Salt Lake (USA), Pampa (Laguna Colorada Chica and Laguna Colorada Grande, separated by 23 Km), and Lake Grassmere (New Zealand). Table S1. Statistics of Salinibacter MAGs recovered using different bioinformatic tools. MAGs selected for further analysis and taxonomic classification are marked in red. Text S1: In addition to the taxonomic study, here we assessed the different tools SPADES and MegaHIT assemblers, and MetaBAT binning tools selecting contigs with length > 2,000 pbs or > 5,000 pbs to retrieve the best quality MAG (Sup. Table S1). We observed that different tools and combinations rendered different qualities of the MAGs. The selection of contigs with length > 5,000 pbs binning rendered MAGs with a lower genome size, lower completeness and similar contamination. From the FF metagenome (Romania), the highest quality MAG was retrieved using the assembler SPADES and MetaBAT binning tool using a minimum contig length of 2,000 pbs. From CCH and CG metagenomes (Argentina), the highest quality MAGs were retrieved using the assembler MegaHIT and MetaBAT binning tool using a minimum contig length of 2,000 pbs (Sup. Table S1). Figure S2. Genomic clustering based on Average Amino-acid Identity (AAI) of genomes included in the study. Figure S3. Pangenome hierarchical clustering based on the presence (grey) or absence (black) of orthologous genes. Table S2. Pangenome statistics between genomes belonging to the same species. Table S3: CRISPR-Cas systems found in the Salinibacter pepae and Salinibacter grassmerensis genomes. Table S4. Cell morphologies of the new isolates. All cells have been cultivated onto MA agar. for 10 days at 12ºC. The morphology was ob