Spirochaete

[8][9] Endoflagella are anchored at each end (pole) of the bacterium within the periplasmic space (between the inner and outer membranes) where they project backwards to extend the length of the cell.

Spirochaete bacteria are diverse in their pathogenic capacity and the ecological niches that they inhabit, as well as molecular characteristics including guanine-cytosine content and genome size.

Pathogenic members of this phylum include the following: Salvarsan, the first partially organic synthetic antimicrobial drug in medical history, was effective against spirochaetes and primarily used to cure syphilis.

Molecular markers in the form of conserved signature indels (CSIs) and CSPs have been found specific for each of the orders, with the exception of Brevinimetales, that provide a reliable means to demarcate these clades from one another within the diverse phylum.

[19] CSIs have also been found that further differentiate taxonomic groups within the Borreliaceae family that further delineate evolutionary relationships that are in accordance with physical characteristics such as pathogenicity (viz.

[19] This CSI is a 3 amino acid insert in the flagellar basal body rod protein FlgC which is an important part of the unique endoflagellar structure shared by Spirochaetota species.

Avitreponema" Treponema The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[30] and National Center for Biotechnology Information (NCBI).

Cross section of a spirochaete cell
Endoflagella Components. Legend: Fig. 1: A cross-section of a typical spirochete cell showing endoflagella located in the periplasm between the inner cytoplasmic membrane and the outer membrane. Periplasm, consisting of a gel-like matrix, provides a semi-stable medium to secure endoflagella during rotation. The axial filament, indicated in red, is composed of bundles of endoflagella.
Fig. 2: A side-view of a spirochete cell which shows two axial filaments in opposing motion. One axial filament rotates in a clockwise orientation; an adjacent axial filament rotates in a counter-clockwise orientation. Rotation of the endoflagella creates torsion and drives the corkscrew rotation of the cell.
Fig. 3: An expanded view of the cellular membranes that surround endoflagellum. Both the inner and outer membrane contain a phospholipid bi-layer, with non-polar fatty acid chains in-ward of polar phosphorus heads. Peptidoglycan, the cell wall, provides structure in bacterial microorganisms. Axial filaments are superior to the peptidoglycan.