Next-Generation DNA Sequencing (NGS)

Profile and Identify Dominant Members of a Microbial Community

Next-generation DNA sequencing (NGS) is a collective term for a group of advanced technologies that allow the determination of the exact order of nucleotides present in a DNA molecule. No other technique yet developed offers the ability to better examine microbial community composition in environmental samples and answer the question: Who is there?

Identification: NGS also commonly called metagenomics provides identification of microorganisms present in an environmental sample often down to the genus level with no prior knowledge of the microbial community composition.  Although function cannot always be predicted from phylogeny, comprehensive identification of the microorganisms present offers unprecedented insight into the potential microbial processes occurring in the environment.

Profile Comparisons:  Comparisons of next-generation sequencing results between samples can reveal important differences or shifts in the microbial community by location, over time, or in response to site activities.

When to use NGS:  NGS is most appropriate for identifying members of the microbial community present in a sample when little is known about the process in question. Results provide insight into the potential microbial activities and can be used to develop tools or select qPCR targets for routine monitoring and ultimately controlling a complex microbial process.  For contaminants with well characterized biodegradation pathways, other MBTs like CENSUS qPCR or QuantArray may be more appropriate.

How does it work? While each platform is unique, the overall steps and the underlying concepts are similar. DNA is extracted from the sample and fragmented into a library of small segments that are amplified and subsequently sequenced in millions of parallel reactions. The sequencing step is similar to previous methods – the bases of each DNA fragment are sequentially identified from light signals emitted as the complement to each fragment strand is re-synthesized. The net result is a set of newly identified strings of nucleotides called “reads” that represent members of the microbial community present in the original sample.