Project description:Metagenome-assembled genomes (MAGs) of Candidatus Nanohaloarchaeota and the closely related lineages from soda-saline lakes in China
Project description:Anthropogenic activities such as urbanization and agriculture can potentially pose a threat to neighboring freshwaters through nitrate and phosphorous contamination, which over time may lead to lake eutrophication. In such nitrogen-polluted environments, oxygen is depleted, and plants die and decompose. This enhances denitrifying microbes that respire under hypoxic/anoxic conditions by reducing nitrate instead of molecular oxygen and using plant remnants (lignocellulose) as carbon source. Microbial lignocellulose degradation has been well-studied for both aerobic- and anaerobic conditions; however, its degradation during denitrification remains largely unknown. Here we have applied a combination of gas kinetics and meta-omics techniques to enrich and analyze microbial communities from 10 eutrophic lakes to identify a set of core microbial metagenome-assembled genomes (MAGs) present in all the eutrophic lakes. We have further investigated their strategies and enzyme profiles for degrading lignocellulose under denitrifying conditions. We identified Pseudomonadota, Bacteroidota, Verrucomicrobiota, and Actinomycetota as the most abundant phyla and they were present in enrichments from all eutrophic lakes having a key role in denitrification and fermentation. Lignocellulose degradation was, however, dominated by species outside the core microbiome, i.e., there were differing key degraders between lakes, suggesting some level of lake-specialization. Among these we observed potential respiratory DNRA pathways, and they expressed a broad range of CAZymes targeting the various lignocellulose subfractions. Interestingly, many of the detected MAGs contained NO dismutases, enzymes postulated to convert NO to molecular oxygen and dinitrogen gas.
Project description:Despite cultivation of many representatives of rich bacterial communities inhabiting alkaline soda lakes, members of the bacterial phylum Verrucomicrobiota have so far been detected only by molecular techniques. Here, we used alginate as a selective substrate to enrich and isolate two strains of haloalkaliphilic Verrucomicrobiota. The isolates share identical 16S rRNA gene sequences and represent a new genus, and, together with metagenome assembled genomes, a new family within Opitutales. Cells of strains AB-alg1T (from soda lakes) and AB-alg4 (from soda soils) are small motile cocci forming submerged colonies in soft alginate agar. They are saccharolytic heterotrophs growing aerobically on polysaccharides (alginate, starch and inulin) and sugars (glucose, fructose, mannose, sucrose, melezitose, maltose and cellobiose). They also grow anaerobically by fermentation of alginate and D-mannose and by coupling incomplete denitrification to oxidation of alginate. Both isolates are obligately alkaliphilic and moderately salt-tolerant. The dominant membrane phospholipids include phosphatidylcholine and cardiolipin. The genome of AB-alg1T features polysaccharide lyases of the PL6, 7, 15, 17, 38, and 39 families for depolymerization of alginate. On the basis of phenotypic and distinct phylogeny, we propose classification of strains AB-alg1T (JCM 35393T=UQM 41574T) and AB-alg4 as Verruconatronum alginilyticum gen. nov., sp. nov. within a new family Verruconatronumaceae.
Project description:In this study we used metaproteomics to discern the metabolism and physiology of the microorganisms occurring in the phototrophic mats of four soda lakes in the interior of British Columbia, Canada. Binned and assembled metagenomes were used as the database for protein identification.
Project description:A new haloalkaliphilic species of Wenzhouxiangella, strain AB-CW3 was isolated from a system of alkaline soda lakes in the Kulunda Steppe. Its complete, circular genome was assembled from combined nanopore and illumina sequencing and its proteome was determined for three different experimental conditions: growth on Staphylococcus cells, casein, or peptone. AB-CW3 is an aerobic bacterium feeding mainly on proteins and peptides.
