B rachyspira

Abstract

Bra.chy.spi'ra. (Gr. adj. brachys , short; Gr. n. spira , a coil, helix; N.L. fem. n. Brachyspira , describing a bacterium that resembles a short helix). Spirochaetes / Spirochaetia / Spirochaetales / Brachyspiraceae / Brachyspira The genus Brachyspira consists of obligately anaerobic, aerotolerant spirochetes, which inhabit the intestinal tracts of birds and mammals, including humans. They have been found globally in free‐living birds. The type species of the genus is Brachyspira aalborgi . There are numerous yet‐to‐be characterized brachyspire species. Brachyspires have fastidious growth requirements requiring chemically complex culture media supplemented with blood or serum. The best studied species, Brachyspira hyodysenteriae, requires cholesterol and phospholipid for growth. The brachyspires are chemoorganotrophic, using various simple carbohydrates for growth. Metabolic products are acetate, butyrate, H 2 , and CO 2 . Brachyspira spp. use NADH oxidase as defense against oxygen exposure. Species are differentiated by 16S rRNA gene sequences and genome DNA homology comparisons (chemical and digital). Genome sequences of the type strains of every species except B. aalborgi are publicly available. There are nine Brachyspira species, of which eight are considered enteropathogenic for their host animal. Diseases associated with the brachyspires include swine dysentery, spirochetal colitis, and intestinal spirochetosis. Dysenteric species ( Brachyspira hyodysenteriae , Brachyspira suanatina , and Brachyspira hampsonii ) form strongly hemolytic (i.e., beta hemolytic) colonies on trypticase soy blood agar. Other species are “weakly” hemolytic. B. hyodysenteriae cells exchange chromosomal genes via VSH‐1, a novel GTA (gene transfer agent). MLST (multiple locus sequence typing) analyses have been applied to investigate B. hyodysenteriae and Brachyspira pilosicoli epidemiology and to interpret species evolution. A database of STs (MLST sequence types) for B. hyodysenteriae strains has been established. DNA G + C content (mol%) : 24.6–27.5 ( T m ; genome sequence). Type species : Brachyspira aalborgi Hovind‐Hougen, Birch‐Andersen, Henrik‐Nielsen, Orholm, Pedersen, Teglbjaerg and Thaysen 1983, 896 VP (Effective publication: Hovind‐Hougen, Birch‐Andersen, Henrik‐Nielsen, Orholm, Pedersen, Teglbjaerg and Thaysen 1982, 1135).