Journal of Forensic Research

Molecular Forensic Approaches to the Taxonomic Assessment of Bacteria in a Commercial Consortia

Abstract

Luke Masson, Thomas A. Edge, Christine Maynard, Roland Brousseau, Nathalie Fortin, Charles W. Greer and Jack T. Trevors

The characterization of low complexity (only a few species present) bacterial communities or commercial consortia products in terms of microbial composition can require a variety of molecular techniques for supporting forensic investigations. We examined a low complexity commercial consortium productfor water treatment application as a model for a tiered molecular approach to studying microbial communities. PCR amplification of 16S rDNA and cpn60 genes were performed on total genomic DNA extracted from the consortium. First, the PCR amplicons were cloned, sequenced and subjected to both DGGE and RFLP analysis, or they were fluorescently labeled and hybridized to a dual backbone taxonomic DNA microarray. Secondly, total genomic DNA from the commercial consortium was subjected to quantitative PCR to determine the concentration of the different components.

The data showed that the dual backbone DNA microarray is extremely useful as a first step to identify the major members of the consortium, including lot-to-lot variation of the commercial product, as validated by independent analyses. More importantly, the DNA microarray proved to be a useful screening tool to detect unexpected and potentially pathogenic microbes in the commercial product. This tiered approach using a DNA microarray screen can be a useful guide for application of more rapid and targeted molecular tools in forensic investigations of microbial communities.