Biology subjects

Sardina, J. A.

Publications and source records attributed to Sardina, J. A..

2 recordsLinked to original sources

bioRxiv2026

The Evolution of Biomineral Armor in Fungus-farming Ants

Biomineralization has enabled remarkable adaptations across the animal kingdom, including defensive structures and rock-grinding teeth. Although calcium carbonate is a common biogenically formed mineral found in all extant animal phyla, it is only recently known in insects and almost universally occurs with minimal magnesium content. A high-Mg calcite armor layer, covering most of the exoskeleton, was recently discovered in the fungus-farming ant Acromyrmex echinatior. Here, using a combination of scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction, paired with genome-scale phylogenetic analysis based on ultraconserved elements (UCEs), we characterize the evolution of biomineralization in fungus-farming ants. We show the presence of high-Mg calcite biomineral in 35 of 50 fungus-farming ant species studied, including taxa that span all major agricultural lineages. The biomineral is absent in all 16 myrmicine outgroup ant species, indicating an origin of the biomineral within ant agriculture, with ancestral state reconstruction analysis slightly supporting multiple origins within the fungus-farming ant clade. We then show that the occurrence of the biomineral is closely associated with the ancient mutualism with antimicrobial-producing Pseudonocardia, finding biomineral presence to be significantly correlated with the Pseudonocardia symbiont and the cuticular symbiotic structures that maintain these bacteria. Furthermore, we reveal significant inter-species variation in mineral composition and coverage, as well as intra-colony caste-specific differences, highlighting its adaptive complexity. Collectively, this work demonstrates that the innovation of a high-Mg calcite armor is strongly associated with the evolution of ant agriculture, revealing a rare biomineral to be widespread in the fungus-farming ants.

evolutionary biology↗

bioRxiv2024

Large-scale investigation for antimicrobial activity reveals novel defensive species across the healthy skin microbiome

The human skin microbiome constitutes a dynamic barrier that can impede pathogen invasion by producing antimicrobial natural products. Gene clusters encoding for production of secondary metabolites, biosynthetic gene clusters (BGCs), that are enriched in the human skin microbiome relative to other ecological settings, position this niche as a promising source for new natural product mining. Here, we introduce a new human microbiome isolate collection, the EPithelial Isolate Collection (EPIC). It includes a large phylogenetically diverse set of human skin-derived bacterial strains from eight body sites. This skin collection, consisting of 980 strains is larger and more diverse than existing resources, includes hundreds of rare and low-abundance strains, and hundreds of unique BGCs. Using a large-scale co-culture screen to assess 8,756 pairwise interactions between skin-associated bacteria and potential pathogens, we reveal broad antifungal activity by skin microbiome members. Integrating 287 whole isolate genomes and 268 metagenomes from sampling sites demonstrates that while the distribution of BGC types is stable across body sites, specific gene cluster families (GCFs), each predicted to encode for a distinct secondary metabolite, can substantially vary. Sites that are dry or rarely moist harbor the greatest potential for discovery of novel bioactive metabolites. Among our discoveries are four novel bacterial species, three of which exert significant and broad-spectrum antifungal activity. This comprehensive isolate collection advances our understanding of the skin microbiomes biosynthetic capabilities and pathogen-fighting mechanisms, opening new avenues towards antimicrobial drug discovery and microbiome engineering.

microbiology↗