These findings expand the phylogenetic and functional landscape of geothermal bacteria and identify Ca.
Abstract
Geothermal environments harbor abundant microbial diversity, yet rare lineages remain poorly resolved, limiting understanding of ecosystem function and evolutionary innovation under energy limitation. Here, we describe Candidatus Vitaminotrophota, a previously unrecognized bacterial phylum represented by 35 metagenome-assembled genomes (MAGs) from Tengchong hot spring sediments, China. Phylogenomic analyses support a coherent internal taxonomy comprising one order, two families and four candidate genera. Metabolic reconstruction indicates a predominantly anaerobic, mixotrophic lifestyle, with widespread carbon fixation potential via the Wood-Ljungdahl pathway and a noncanonical CODH/ACS architecture featuring divergent acsA paralogs. Nitrogenase structural genes (nifHDK) occur in two genera, suggesting diazotrophic potential in part of the lineage. All MAGs encode complete or near-complete cobalamin and pantothenate biosynthesis pathways, and most retain conserved thiamine pathway components, alongside transport systems consistent with corrinoid and metal acquisition. Ca. Vitaminotrophota dominated community-level cobalamin biosynthetic potential in several samples, reaching 99.11% and accounting for >50% in nearly half of the samples. Conserved flagellar and chemotaxis gene sets suggest capacity to navigate steep physicochemical gradients. These findings expand the phylogenetic and functional landscape of geothermal bacteria and identify Ca. Vitaminotrophota as a candidate contributor to carbon fixation and vitamin-mediated metabolic interactions in nutrient-limited hot springs.
Soda lakes represent some of the most extreme aquatic ecosystems on Earth, yet their microbial diversity and functional potential remain poorly characterized, particularly in East Africa. This study presents the first shotgun metagenomic analysis of bacterial communities inhabiting both water and sediment of Small Momela Lake, a soda lake in northern Tanzania. Samples were sequenced using Illumina NovaSeq and analyzed with MetaPhlAn4 and HUMAnN3 to resolve taxonomic composition, diversity patterns and predicted metabolic functions. Results showed 27 distinct species within Pseudomonadota, Bacteroidota, Firmicutes, Cyanobacteria and Verrucomicrobia dominated by sulfur-cycling Thioalkalivibrio denitrificans and uncultured Candidatus lineages. Notably, based on currently available literature multiple taxa were detected for the first time in soda lake environments globally, within Africa and East Africa, expanding the known biogeography of extremophiles. Functional profiling revealed a strong enrichment of nucleotide and amino acid biosynthesis pathways, alongside marker genes linked to pH homeostasis, osmotic stress tolerance, sulfur metabolism and carbon fixation. These features suggest pronounced metabolic flexibility supporting microbial persistence under extreme alkaline and saline conditions. These findings underscore Small Momela Lake as a critical reservoir of novel, functional bacterial resources with promising applications in biotechnology and bioprospecting.
A. A. Siima, Sadikiel E. Kaale, F. Mpenda et al.· Discover Life· 0 citations
Environmental filtering is a major driver of microbial community assembly in Antarctic ecosystems, yet its influence on biosynthetic potential and antimicrobial resistance remains poorly understood. Here, we analyzed 319 medium- to high-quality metagenome-assembled genomes (MAGs) recovered from four Antarctic sites (Whalers Bay, Crater Lake, Fumarole Bay, and Hannah Point) to investigate the relationship between geochemical gradients, biosynthetic gene clusters (BGCs), and antimicrobial resistance genes (ARGs). Integrating genome-resolved metagenomics, biosynthetic mining, resistome profiling, and environmental analyses, we identified 1,197 BGCs, with terpene clusters representing more than 25% of the total. Several biosynthetic hotspots were detected, including an Acidobacteriota MAG harboring 62 BGCs. Resistome composition exhibited strong site-specific structuring and was significantly associated with geochemical variables, particularly cobalt, iron, organic carbon, and thermal variation. Network analyses revealed highly connected MAGs affiliated with Pseudomonadota and Actinomycetota, linking diverse BGC and ARG classes. At the same time, genomic co-localization of biosynthetic and resistance determinants suggests potential adaptive associations between secondary metabolism and self-resistance mechanisms. Together, these findings demonstrate that environmental filtering shapes both the taxonomic and functional organization of Antarctic microbiomes and highlight polar ecosystems as reservoirs of unexplored biosynthetic diversity with potential biotechnological relevance.
William B. Medeiros, Kelly Hidalgo-Martinez, D. D. P. S. Penna et al.· World Journal of Microbiolog...· 0 citations
The El Tatio geothermal field is identified as a rich source of putative hydrolase-encoding genes for future biochemical and biotechnological exploration and expands current knowledge of microbial diversity and functional potential in high-altitude geothermal ecosystems.
Bernardita Valenzuela, Ignacio Navarrete-Diaz, Mayra Cayo et al.· International Journal of Mol...· 0 citations
Recognizing the central role of microorganisms in greenhouse gas (GHG) cycling in aquaculture systems, we provide a genome- and gene-centric perspective on the metabolic potential for CO₂ and CH₄ cycling in prawn aquaculture ponds across seasons and contrasting culture practices. Using TaxVAMB, we recovered 78 high- and medium-quality metagenome-assembled genomes (MAGs), including previously underappreciated taxa such as Bathyarchaeia and Terriglobia. Metabolic profiling revealed that CO₂ and CH₄ cycling constitute a minor fraction of the pond’s metabolic potential, dominated instead by heterotrophic processes such as fermentation, oxygen metabolism, and iron reduction. The relative metabolic weight of these carbon-cycling pathways was lower than that reported for permafrost, wetland, peatland, deep-sea, and human gut microbiomes. An integrated metabolic network suggested that genetic potential for CO₂ production is primarily driven by pyruvate and acetyl-CoA oxidation, while methanogenesis and methane oxidation genes together encode the potential for internal carbon-recycling loops via canonical archaeal and bacterial pathways. Seasonal dynamics, rather than management treatment, strongly influenced functional gene abundances, with CO₂ fixation and CH4 oxidation genes increasing toward the late season. Bathyarchaeia emerged as the most versatile taxon for CO₂ cycling and methanogenesis, with stable relative abundance across seasons and treatments. This study underscores the role of seasonally evolving microbial networks in regulating carbon turnover and the potential for CO2 and CH4 emissions in prawn aquaculture ponds.
A. Bashar, A. M. Djurhuus, P. Browne et al.· bioRxiv· 0 citations
Analysis revealed genes for metabolizing diverse carbohydrate sources, a complete ectoine synthesis cluster essential for halophily, and genes conferring tolerance to osmotic stress, low temperatures, and pH, underscoring its polyextremophilic capacity.
Ian Ariel Barbosa Nunes, Adan Rodrigues de Oliveira, Adonney Allan de Oliveira Veras et al.· Brazilian Journal of Microbi...· 0 citations
