Transforming microbial genotyping: a robotic pipeline for genotyping bacterial strains

PLoS One. 2012;7(10):e48022. doi: 10.1371/journal.pone.0048022. Epub 2012 Oct 29.

Abstract

Microbial genotyping increasingly deals with large numbers of samples, and data are commonly evaluated by unstructured approaches, such as spread-sheets. The efficiency, reliability and throughput of genotyping would benefit from the automation of manual manipulations within the context of sophisticated data storage. We developed a medium- throughput genotyping pipeline for MultiLocus Sequence Typing (MLST) of bacterial pathogens. This pipeline was implemented through a combination of four automated liquid handling systems, a Laboratory Information Management System (LIMS) consisting of a variety of dedicated commercial operating systems and programs, including a Sample Management System, plus numerous Python scripts. All tubes and microwell racks were bar-coded and their locations and status were recorded in the LIMS. We also created a hierarchical set of items that could be used to represent bacterial species, their products and experiments. The LIMS allowed reliable, semi-automated, traceable bacterial genotyping from initial single colony isolation and sub-cultivation through DNA extraction and normalization to PCRs, sequencing and MLST sequence trace evaluation. We also describe robotic sequencing to facilitate cherrypicking of sequence dropouts. This pipeline is user-friendly, with a throughput of 96 strains within 10 working days at a total cost of < €25 per strain. Since developing this pipeline, >200,000 items were processed by two to three people. Our sophisticated automated pipeline can be implemented by a small microbiology group without extensive external support, and provides a general framework for semi-automated bacterial genotyping of large numbers of samples at low cost.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / classification
  • Bacteria / genetics*
  • Bacterial Typing Techniques / instrumentation
  • Bacterial Typing Techniques / methods*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Genotype
  • Genotyping Techniques / instrumentation
  • Genotyping Techniques / methods*
  • Multilocus Sequence Typing / instrumentation
  • Multilocus Sequence Typing / methods*
  • Polymerase Chain Reaction
  • Reproducibility of Results
  • Sequence Analysis, DNA
  • Software

Substances

  • DNA, Bacterial

Grants and funding

This work was supported by the Science Foundation Ireland (grant number 05/FE1/B882 to MA). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.