Whole genome shotgun sequencing is an approach to decoding an organism’s entire genome, or the sum of its hereditary information. Processing it as a single unit of data is functionally impossible, so instead it is chopped into short pieces of information that can be sequenced and reassembled. This method can generate errors, but can also be extremely rapid, which may balance out the risk of mistakes, depending on the organism under investigation. Genetics organizations collect sequenced genomes from specific organisms and make them available for research and comparison.
This process starts with chopping up the genetic material into units of information that can be processed. One way to do this is with the use of restriction enzymes which cut through the strands of data. Another option is to mechanically separate the strands of Deoxyribonucleic Acid (DNA) with equipment designed to turn it into digestible chunks. These can be inserted into vectors and replicated in colonies of bacteria to create a DNA library, with numerous copies of the information available for sequencing.
The next step involves sequencing these short lengths of data. They can be reassembled by looking for overlaps, where data matches up with data from other strands. In whole genome shotgun sequencing, there can be some room for error, as identical strands might be mixed up, or an overlap might not be readily identifiable. The whole genome shotgun method is less painstaking than other options, however, which makes it more practical for situations where rapid sequencing is desired for immediate results.
Researchers can utilize this approach for a variety of activities. They may be interested in generating sequences of multiple genomes for comparison purposes, or in looking at a specific organism’s DNA for more information about it. The name is a reference to the somewhat broad and scattered effect of a shotgun; whole genome shotgun sequencing provides rapid, broad coverage, even if it might be slightly inaccurate.
Facilities capable of performing whole genome sequencing can be found in a variety of locations around the world. Some focus on providing services to their own researchers and personnel. Others process DNA for a fee, and may offer whole genome shotgun sequencing. Customers need to provide them with viable samples that meet standards set by the lab, and wait times can vary depending on workload and complexity. Humans, for example, have an extremely large genome that may take more time to process than one for an organism with far fewer gene pairs.