Siwa spring microbiomes as reservoirs of biosynthetic gene clusters: Unlocking natural product potential.

The rising demand for novel therapeutics, including antimicrobial, anticancer, and anti-inflammatory agents, underscores the need for new drug discovery strategies. Microbial communities represent rich reservoirs of bioactive compounds encoded by biosynthetic gene clusters (BGCs), yet traditional approaches remain limited by the inability to culture most microorganisms and the frequent rediscovery of known metabolites. Sequence-based metagenomics provides a transformative solution by directly identifying BGCs from environmental DNA. Using NovaSeq X Plus shotgun sequencing, we explored the biosynthetic potential of microbial communities in two previously unstudied brackish springs of the Siwa Oasis, Cleopatra and Fatnas. These ecosystems were dominated by bacteria (99.2%), with archaea being nearly absent (< 0.1%), and the microbial composition consisted largely of mesophilic taxa from Pseudomonadota, Bacteroidota, Actinomycetota, and Planctomycetota, which together accounted for 98.2% of the community. Our integrated bioinformatics pipeline enabled the reconstruction of 37 medium-to-high-quality metagenome-assembled genomes (MAGs), and recovered 147 BGCs mostly from Pseudomonadota, Actinomycetota, and Acidobacteriota phyla. Terpene (n = 23) and ribosomally synthesized and post-translationally modified peptide (RiPPs; n = 22) BGCs predominated within Cleopatra Spring, whereas RiPPs (n = 20) represented the dominant class recovered from Fatnas Spring. None of the recovered gene clusters mapped to experimentally validated entries in the MIBiG database (distance > 0.4), and 96.6% displayed structural divergence from the gene cluster families catalogued in the BGC Atlas. These results highlight the Siwa Oasis as a promising reservoir of unexplored biosynthetic potential and a valuable resource for natural product discovery to address global health challenges.