Direct and culture-enriched 16S rRNA sequencing of cecal content of healthy horses and horses with typhlocolitis.
Authors: Zakia Luiza S, Gomez Diego E, Caddey Benjamin B, Boerlin Patrick, Surette Michael G, Arroyo Luis G
Journal: PloS one
Summary
# Equine Typhlocolitis and Caecal Microbiota: Methodological Insights from Direct and Culture-Based Sequencing Understanding shifts in the caecal microbiota of horses with typhlocolitis requires robust analytical methods, yet the relative merits of direct versus culture-enriched sequencing approaches remain understudied in this population. Researchers compared caecal bacterial communities from six healthy horses and six with acute typhlocolitis using both direct 16S rRNA gene sequencing and culture-enriched profiling across five different media types, with cultures incubated aerobically (MacConkey) or anaerobically. Direct sequencing revealed significantly lower alpha diversity (bacterial richness and evenness) in diseased horses compared to healthy controls, whilst culture-based methods consistently identified Firmicutes and Bacteroidetes as dominant phyla—though notably, Proteobacteria dominated only on aerobic MacConkey agar. Notably, two diarrheic horses showed elevated relative abundance of Fusobacteriota, a finding warranting further investigation given its potential pathogenic significance in equine colitis. For practitioners and researchers, these results highlight that direct caecal sequencing captures greater bacterial diversity than cultured approaches and may prove more sensitive for detecting disease-associated dysbiosis; however, culture-enriched methods complement molecular work by identifying cultivable species and offering functional characterisation opportunities.
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Practical Takeaways
- •Reduced microbial diversity in the cecum may be a marker of typhlocolitis; understanding this dysbiosis could inform probiotic or dietary interventions for colitis cases
- •Culture-enriched sequencing offers a viable complementary method to direct sequencing for studying equine gut microbiota in clinical research and diagnostics
- •Fusobacteriota warrants further investigation as a potential pathogenic or indicator organism in equine colitis cases
Key Findings
- •Alpha diversity of cecal microbiota was significantly lower in horses with typhlocolitis compared to healthy horses (P < 0.05)
- •Direct 16S sequencing revealed greater bacterial richness in cecal contents compared to cultured plates (P < 0.05)
- •Firmicutes and Bacteroidetes were predominant phyla in both healthy and diseased horses across most culture media
- •Higher relative abundance of Fusobacteriota was identified in 2/6 diarrheic horse samples, suggesting a potential role in equine colitis