Fuente: PubMed "microbial biotechnology" Appl Environ Microbiol. 2026 May 11:e0047526. doi: 10.1128/aem.00475-26. Online ahead of print.ABSTRACTDespite the successful cultivation of many microbes from rich bacterial communities inhabiting alkaline soda lakes, members of the bacterial phylum Verrucomicrobiota have so far been detected only through metagenomics. 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 representing a new genus lineage, and, together with other metagenome assembled genomes, a new family within Opitutales. Cells of strains AB-alg1T (from soda lakes) and AB-alg4 (from soda solonchak soils) are small and 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 phosphatidylcholines and diphosphatidylglycerols (cardiolipins). The genome of AB-alg1T features polysaccharide lyases of the PL6, 7, 15, 17, 38, and 39 families for depolymerization of alginate. Based on distinct phenotype and phylogeny, we propose classification of strains AB-alg1T (JCM 35393T=UQM 41574T) and AB-alg4 as Verruconatronum alginivorum gen. nov., sp. nov. within a new family Verruconatronumaceae.IMPORTANCEAlkaline soda lakes and soils are extreme habitats dominated by obligate haloalkaliphic prokaryotes, some of which can produce alkali- and salt-stable polysaccharide-degrading exoenzymes useful for industrial and domestic applications. However, so far, little was known about the microbial potential for mineralization of acidic polysaccharides, such as alginate, in these habitats. The described isolates are the first representatives of a new family within the phylum Verrucomicrobiota specializing in the degradation of alginate and related polysaccharides. We present the key enzymatic machinery for alginate breakdown. These enzymes are high-pH tolerant and have potential for industry applications, for example, in washing powders and biomass waste recycling. Furthermore, the new family is one of the most abundant taxa in alkaline environments, and these environments are not known to harbor signature alginate producing biota, such as brown algae. This way, our study opens a new window on polysaccharide turnover in alkaline environments.PMID:42112890 | DOI:10.1128/aem.00475-26