Phylogenetic position of Taylorella equigenitalis determined by analysis of amplified 16S ribosomal DNA sequences.

The study focuses on determining the genetic place of Taylorella equigenitalis, a bacterium involved in a horse disease, by analyzing its DNA. The analysis showed that it falls in the same group as certain bacteria but surprisingly differs from others despite similarities in their genetic content.

Detailed Explanation

• The research revolves around the phylogenetic placement of Taylorella equigenitalis, a bacterium that was previously known as Haemophilus equigenitalis. This bacterium is responsible for a sexually transmitted disease in horses known as Contagious Equine Metritis (CEM). The phylogenetic position of a species is vital in indicating its evolutionary connections with other organisms.
• The researchers determined the 16S ribosomal DNA sequence of T. equigenitalis. This type of DNA sequencing is a common method used in microbiology to identify and classify bacteria. By comparing the DNA sequences, scientists can determine how closely related different species are.
• Upon analysis of this sequence, it was found that T. equigenitalis holds its position in the beta subclass of the Proteobacteria class. This placed it apart from Haemophilus Influenzae, a bacterium which belongs to the gamma subclass of Proteobacteria. This identification is significant as it helps in the classification of the bacterium and offers insights into its characteristics and potential behaviors.
• Furthermore, a strong evolutionary relationship was detected between T. equigenitalis and two other bacteria: Alcaligenes xylosoxidans and Bordetella bronchiseptica. Other bacteria such as Spirillum volutans and Chromobacterium fluviatile (also known as Iodobacter fluviatile) were found to be part of the same group as T. equigenitalis, but slightly removed – indicating a lesser degree of relatedness.
• Interestingly, despite these evolutionary relationships, there were considerable differences found in the G + C content of these bacteria’s genomes. G + C content, or guanine-cytosine content, refers to the percentage of nitrogenous bases in a DNA molecule that are either guanine (G) or cytosine (C). This discrepancy was unexpected, as organisms that share a close evolutionary relationship typically have similar GC content. This serves as an example of how genetic diversity can exist even amongst closely related microorganisms.