Equine Microbiome Profiling Advanced With Rapid Oxford Nanopore Sequencing

Rapid Bacterial Profiling: A New Era for Equine Microbiome Research

The research team, which includes J. Leng, C. Tait, B. Alsubaie, A.H.M. Van Vliet, P. Sells, R.M. La Ragione, and C. Proudman, conducted this work under the umbrella of the Alborada Well Foal 2 project. Led by Dr. Joy Leng, the project aims to elucidate how the foal gut microbiome develops by investigating the microbial communities of both mares and their foals. By utilizing samples collected during a pilot study, the team successfully profiled bacterial communities across four distinct anatomical sites: feces, saliva, skin, and milk.

Overcoming the Bottlenecks of Short-Read Sequencing

Historically, equine microbiome studies have relied heavily on high-throughput, short-read sequencing technologies. Because of the high cost of equipment such as Illumina and Ion Torrent sequencers, researchers have frequently relied on external service providers to process samples. Furthermore, these workflows often require the researcher to possess prior experience in coding-based programs to analyze the resulting data. The reliance on external services has historically resulted in slow analytical workflows, limiting the clinical utility of bacterial community profiling in horses.

The transition to third-generation sequencing platforms, such as those from Oxford Nanopore Technologies (ONT), addresses several technical limitations inherent in previous methods. While second-generation platforms are instrumental in increasing speed and throughput, they are constrained by short read lengths, typically ranging from 100 to 400 base pairs. Additionally, these platforms do not allow for the control or management of the sequencing reaction in real time.

In contrast, Oxford Nanopore’s MinION Mk1D platform allows for read lengths of over 10,000 base pairs, providing researchers with the ability to perform real-time data acquisition and total control over the reaction. By sequencing the full-length 16S rRNA gene—which is approximately 1,500 base pairs in length—the University of Surrey team generated high-quality microbiome profiles that provide a more complete taxonomic picture than partial gene sequencing.

Methodology and Technical Performance

The study’s methodology involved extracting bacterial DNA from horse udder skin swabs, saliva swabs, fecal samples, and milk samples. Once prepared, the samples were sequenced using a flow cell on the MinION Mk1D. The resulting data were analyzed using Oxford Nanopore’s user-friendly EPI2ME software, which enabled rapid bacterial identification without necessitating extensive bioinformatics expertise. Extra analyses on exported taxa abundance data were performed using the R programming language.

The results confirmed that the long-read sequencing approach successfully identified distinct bacterial communities across the different anatomical sites. Quality control figures generated by the EPI2ME software indicated high read quality, with nearly all reads capturing the full 1,500 bp length of the 16S rRNA gene. This consistency in read length and quality demonstrates the efficiency of the workflow for researchers who require both speed and high-quality data.

Future Clinical and Research Implications

This study serves as a proof-of-concept for the viability of in-house microbiome analysis. By successfully profiling non-intestinal ecological niches—such as skin and milk, which have been largely neglected in previous equine research—the team has provided a foundation for future clinical diagnostics. The research highlights the potential for this technology to act as a future clinical tool for rapid bacterial identification, moving the field beyond its current reliance on external service models.

As noted by the University of Surrey, this work showcases the potential of Oxford Nanopore sequencing as both a research tool and a future clinical instrument. By bypassing the logistical and financial barriers associated with traditional short-read sequencing, the MinION Mk1D platform offers a scalable solution for laboratories investigating the equine microbiome. The study concludes that this long-read approach provides a critical foundation for ongoing and future investigations into the complex microbial landscapes that influence equine gastrointestinal, respiratory, and musculoskeletal health.

Sources: PHYS, Frontiersin.