Taxonomic diversity and functional prediction of extremophilic bacteria of small Momela Lake, Tanzania

Abstract

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.