Brachyspira

Abstract

Bra.chy.spi'ra. Gr. adj. brachys short; L. fem. n. spira a coil, spiral; N.L. fem. n. Brachyspira a short spiral, describing a bacterium that resembles a short spiral. Spirochaetes / Spirochaetia / Spirochaetales / Brachyspiraceae / Brachyspira Brachyspira spirochetes are helical shaped bacteria with regular coiling patterns . Cells measure 2–11 µm by 0.2–0.4 µm. Unicellular, but dividing pairs and occasional chains of three or more cells can be observed in growing cultures. Under unfavorable growth conditions, spherical or round bodies are formed. Gram‐stain negative. Obligately anaerobic, aerotolerant . Cell ends may be blunt or pointed. Cells have a typical spirochete cell ultrastructure, consisting of an outer sheath, helical protoplasmic cylinder, and internal flagella in the space between the protoplasmic cylinder and outer sheath. Brachyspire cells have 8–30 flagella per cell depending on the species (flagellar number usually correlates with cell size and species of smaller cells have fewer flagella). Flagella attach subterminally in equal numbers at each cell end, wrap around the protoplasmic cylinder, and their free ends overlap in the middle of the cells. Flexing and creeping motility at 22°C; translational movement in liquids at 37–42°C. Cultured anaerobically on commercially available media (trypticase soy or brain heart infusion broths) containing a carbohydrate growth substrate and supplemented with defibrinated blood or animal (calf) serum. Grows at 36–42°C, optimally at 37–39°C. Population doubling times on glucose in broth cultures are 1–5 h (not reported for Brachyspira aalborgi ). Chemoorganotrophic, using various carbohydrates for growth. Possess NADH oxidase for reducing molecular oxygen. Consume oxygen during growth in culture broth beneath a 1 % oxygen atmosphere. Acetate, butyrate, H 2 , and CO 2 are major endproducts of glucose metabolism. Higher amounts of H 2 than CO 2 are produced . Weakly hemolytic except for Brachyspira hyodysenteriae which exhibits β‐hemolysis (strongly hemolytic). Associated with animal and human hosts. Some species are pathogenic. The genus Brachyspira is distinguished from other spirochete genera based on 16S rRNA gene sequences . Brachyspira species share high 16S rRNA sequence similarity with each other. Species can be differentiated by DNA–DNA relative reassociation and MLEE (multilocus enzyme electrophoresis) analyses. Similar to other spirochete genera, Brachyspira is insensitive to the antibiotic rifampin. DNA G + C content ( mol %): 24.5–27.1 ( T m ). Type species : Brachyspira aalborgi Hovind‐Hougen, Birch‐Andersen, Henrik‐Nielsen, Orholm, Pedersen, Teglbjaerg and Thaysen 1 9 8 3, 896 VP (Effective publication: Hovind‐Hougen, Birch‐Andersen, Henrik‐Nielsen, Orholm, Pedersen, Teglbjaerg and Thaysen 1982, 1135 VP .).