Multi-locus and long amplicon sequencing approach to study microbial diversity at species level using the MinION™ portable nanopore sequencer

Background: The miniaturised and portable DNA sequencer MinION^TM has demonstrated great potential in different analyses such as genome-wide sequencing, pathogen outbreak detection and surveillance, human genome variability, and microbial diversity. In this study, we tested the ability of the MinION^TM platform to perform long amplicon sequencing in order to design new approaches to study microbial diversity using a multi-locus approach.

Results: After compiling a robust database by parsing and extracting the rrn bacterial region from more than 67,000 complete or draft bacterial genomes, we demonstrated that the data obtained during sequencing of the long amplicon in the MinION^TM device using R9 and R9.4 chemistries was sufficient to study two mock microbial communities in a multiplex manner and to almost completely reconstruct the microbial diversity contained in the HM782D and D6305 mock communities.

Conclusions: Although nanopore-based sequencing produces reads with lower per-base accuracy compared with other platforms, we presented a novel approach consisting of multi-locus and long amplicon sequencing using the MinION^TM MkIb DNA sequencer and R9 and R9.4 chemistries that help to overcome the main disadvantage of this portable sequencing platform. Furthermore, the nanopore sequencing library constructed with the last releases of pore chemistry (R9.4) and sequencing kit (SQK-LSK108) permitted to retrieve the higher level of 1D read accuracy sufficient to characterize the microbial species present in each mock community analysed. Improvements in nanopore chemistry, such as minimising base-calling errors and new library protocols able to produce rapid 1D libraries, will provide more reliable information in near future. Such data will be useful for more comprehensive and faster specific detection of microbial species and strains in complex ecosystems.