Traditionally bacterial species were identified by their phenotypic characteristics. Why is DNA sequencing genotyping a better identification method?
The correct answer and explanation is:
Correct Answer: DNA sequencing genotyping is a better identification method because it provides higher accuracy, allows for identification of non-culturable bacteria, and reveals genetic relationships and evolutionary history.
Explanation:
Traditionally, bacterial identification relied on phenotypic characteristics such as shape, staining properties, metabolism, and growth conditions. These methods were useful in many clinical and environmental settings, but they had limitations. Phenotypic traits can vary depending on environmental conditions, mutations, or the presence of mobile genetic elements. This means two different species could look similar, or the same species might appear different under varying conditions.
DNA sequencing genotyping overcomes these issues by directly analyzing the genetic material of the organism. DNA sequences remain relatively stable and reflect the true evolutionary relationships between organisms. By examining genes that are highly conserved, such as the 16S rRNA gene, scientists can identify bacteria accurately and consistently, regardless of external influences.
This method also allows for the identification of bacteria that cannot be cultured in the lab. Many bacterial species in nature do not grow well or at all in artificial environments, making them invisible to traditional methods. DNA sequencing can detect these unculturable species directly from environmental or clinical samples, expanding the understanding of microbial diversity.
Furthermore, DNA-based methods can detect small genetic differences between closely related species or even between different strains of the same species. This level of resolution is critical in fields like epidemiology, where tracking the source and spread of bacterial infections depends on distinguishing between strains.
Overall, DNA sequencing genotyping is more reliable, comprehensive, and detailed than phenotypic identification. It enables precise classification, improves diagnostics, and supports research into bacterial evolution, antibiotic resistance, and disease outbreaks.