Biology subjects

Vercelli, G. T.

Publications and source records attributed to Vercelli, G. T..

3 recordsLinked to original sources

bioRxiv2025

Niche partitioning by resource size in the gut microbiome

Niche partitioning promotes diversity of the human gut microbiota. However, the molecular basis of resource specialization and niche separation in the gut remains poorly understood. Here we show that structural differences in glycan transporters drive members of the genus Bacteroides, common human gut commensals, to specialize on distinct chain lengths of the same fructan molecule. While species encoding canonical SusCD systems for glycan import -formed by a membrane-embedded barrel capped with a lipoprotein lid- specialized in long-chain fructans, species with smaller lidless transporters, not previously described in Bacteroides, specialized in short-chain fructans. Strikingly, we found that a [~]140-amino acid domain in the SusC barrel is a structural feature that governs substrate preference: deleting it does not impair transport but instead shifts uptake preferences from long-to short-chain fructans. These structural differences predict competitive outcomes in vivo on fructans of varying lengths, suggesting that glycan uptake mechanisms shape ecological niches in the gut and can inform fiber-based dietary interventions. Similar small lidless transporters exist across the Bacteroidota, expanding the paradigm of glycan utilization in this phylum beyond the canonical SusCD architecture.

microbiology↗

bioRxiv2025

A universal surface functionalization technique to chemically enhance live microbial cells

Microbial surface functionalization is a powerful strategy for endowing microbes with novel, non-genetic functions. However, existing methods are often species-specific, limited in scope, and compromise cell viability. Here, we present a universal and modular platform for high-density, reproducible surface functionalization across diverse microbial species--including Gram-positive, Gram-negative, aerobic, and anaerobic bacteria--using multiple molecular classes such as fluorophores, enzymes, and nucleic acids. Our method preserves cell viability, and achieves 50x higher functionalization efficiency than previous methods with a standardized protocol applicable to any azide-containing molecule. Applications of the method show reproducible and tunable phenotypic outcomes at the single-cell level: fluorophore labeling yielded adjustable fluorescence, {beta}-lactamase conferred scalable antibiotic resistance, and DNA coatings modulated adhesion and aggregation. This platform provides quantitative, non-genetic control over microbial phenotypes and complements genetic engineering approaches. It enables new possibilities for microbial design in biotechnology, medicine, and environmental applications where genetic modification is impractical or undesirable.

microbiology↗

bioRxiv2023

Widespread B-vitamin auxotrophy in marine particle-associated bacteria

Microbial community assembly is governed by trophic interactions that mediate the transfer of carbon sources and biomass building blocks between species. However, central metabolism corresponds to only a small fraction of the biosynthetic potential of microbes: metabolites such as antimicrobial compounds, signaling molecules, and co-factors are underexplored forces shaping microbial communities. Here, we focus on B vitamin exchange in coastal marine bacterial communities that degrade particulate organic matter and find that natural seawater communities are vitamin limited. While almost a third of bacterial isolates from these communities are B vitamin auxotrophs, the pioneering degraders that first arrive on particles are vitamin producers that likely support auxotrophs through cross-feeding. However, combining experiments and a resource-explicit model, we show that auxotroph growth is often not restored by coculture with vitamin producers, but rather requires lysis and subsequent vitamin recycling. Our results highlight the importance of vitamin auxotrophies and lysis-mediated cross-feeding as important factors controlling microbial community assembly and succession on marine particles.

microbiology↗