Soto-Perez, P. | Search bioRxiv

bioRxiv2026

Eggerthella lenta evades bacteriophage through reversible megabase-scale inversions of capsular polysaccharide gene clusters

Bacteriophages are a promising tool for microbiome editing, yet their development has been constrained by limited insights into bacteriophage-host interactions within their shared mammalian body habitat. We isolated a lytic phage {Phi}KL11 that efficiently targets a disease-associated member of the human gut microbiota, Eggerthella lenta, during in vitro growth. However, {Phi}KL11 selects for a pre-existing and reversible bacteriophage-resistant sub-population in mice. Long-read sequencing revealed a massive genomic inversion event, representing >50% of the E. lenta genome, enriched in response to bacteriophage infection. Transcriptomics linked this inversion to the altered expression of three capsular polysaccharide synthesis (CPS) gene clusters and transmission electron microscopy confirmed differential capsule production. Finally, we show that {Phi}KL11 has a broad host range attributable to CPS and other strain-variable genes. These findings suggest a previously unrecognized strategy for phage evasion in the gut, involving megabase-scale genomic inversions and reversible capsule variation driving phage resistance.

microbiology↗

bioRxiv2018

Illuminating the microbiome’s dark matter: a functional genomic toolkit for the study of human gut Actinobacteria

Despite the remarkable evolutionary and metabolic diversity found within the human microbiome, the vast majority of mechanistic studies focus on two phyla: the Bacteroidetes and the Proteobacteria. Generalizable tools for studying the other phyla are urgently needed in order to transition microbiome research from a descriptive to a mechanistic discipline. Here, we focus on the Coriobacteriia class within the Actinobacteria phylum, detected in the distal gut of 90% of adult individuals around the world, which have been associated with both chronic and infectious disease, and play a key role in the metabolism of pharmaceutical, dietary, and endogenous compounds. We established, sequenced, and annotated a strain collection spanning 14 genera, 8 decades, and 3 continents, with a focus on Eggerthella lenta. Genome-wide alignments revealed inconsistencies in the taxonomy of the Coriobacteriia for which amendments have been proposed. Re-sequencing of the E. lenta type strain from multiple culture collections and our laboratory stock allowed us to identify errors in the finished genome and to identify point mutations associated with antibiotic resistance. Analysis of 24 E. lenta genomes revealed an \"open\" pan-genome suggesting we still have not fully sampled the genetic and metabolic diversity within this bacterial species. Consistent with the requirement for arginine during in vitro growth, the core E. lenta genome included the arginine dihydrolase pathway. Surprisingly, glycolysis and the citric acid cycle was also conserved in E. lenta despite the lack of evidence for carbohydrate utilization. We identified a species-specific marker gene and validated a multiplexed quantitative PCR assay for simultaneous detection of E. lenta and specific genes of interest from stool samples. Finally, we demonstrated the utility of comparative genomics for linking variable genes to strain-specific phenotypes, including antibiotic resistance and drug metabolism. To facilitate the continued functional genomic analysis of the Coriobacteriia, we have deposited the full collection of strains in DSMZ and have written a general software tool (ElenMatchR) that can be readily applied to novel phenotypic traits of interest. Together, these tools provide a first step towards a molecular understanding of the many neglected but clinically-relevant members of the human gut microbiome.

microbiology↗