''Butyrivibrio'' is a genus of

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

in Class Clostridia. Bacteria of this genus are common in the

gastrointestinal system The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

s of many animals. Genus ''Butyrivibrio'' was first described by Bryant and Small (1956) as

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

, butyric acid-producing, curved rods (or vibroids). ''Butyrivibrio'' cells are small, typically 0.4 – 0.6

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

by 2 – 5 μm. They are

motile Motility is the ability of an organism to move independently using metabolic energy. This biological concept encompasses movement at various levels, from whole organisms to cells and subcellular components. Motility is observed in animals, mi ...

, using a single polar or subpolar monotrichous

flagellum A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

. They are commonly found singly or in short chains but it is not unusual for them to form long chains. Despite historically being described as

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

, their

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

s contain derivatives of

teichoic acid Teichoic acids (''cf.'' Greek τεῖχος, ''teīkhos'', "wall", to be specific a fortification wall, as opposed to τοῖχος, ''toīkhos'', a regular wall) are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohyd ...

, and

electron microscopy An electron microscope is a microscope that uses a beam of electrons as a source of illumination. It uses electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing i ...

indicates that bacteria of this genus have a Gram-positive cell wall type.Beveridge, 1990 It is thought that they appear Gram-negative when Gram stained because their cell walls thin to 12 to 18 nm as they reach stationary phase. ''Butyrivibrio'' species are common in the

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...

s of

ruminant Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microb ...

animals such as

cows Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are called co ...

deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...

and

sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...

, where they are involved in a number of ruminal functions of

agricultural Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...

importance in addition to

butyrate The conjugate acids are in :Carboxylic acids. {{Commons category, Carboxylate ions, Carboxylate anions Carbon compounds Anions ...

production.Miller & Jenesel, 1979 These include fibre degradation, protein breakdown, biohydrogenation of

lipid Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...

s and the production of microbial inhibitors.Blackburn & Hobson, 1962Kalmokoff & Teather, 1997Kepler et al., 1966Dehority & Scott, 1967Polan et al., 1964 Of particular importance to ruminant digestion, and therefore productivity, is their contribution to the degradation of plant structural carbohydrates, principally

hemicellulose A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all embryophyte, terrestrial plant cell walls. Cellulose is crystalline, strong, an ...

.Morris & Van Gylswyk, 1980

Metabolism

''Butyrivibrio'' species are metabolically versatile and are able to

ferment Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic compound, Organic molecules, such as glucose or other sugars, are Catabo ...

a wide range of

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...

sStewart et al., 1997 and cellodextrins.Russell, 1985 Some strains have been reported to break down

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

,Shane et al., 1969 although their ability to sustain growth on cellulose appears to be lost during in vitro culturing. Most isolates are amylolyticCotta, 1988 and are able to degrade

xylan Xylan (; ) ( CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abu ...

by producing xylanolyticHespell et al., 1987Sewell et al., 1988 and

esterase In biochemistry, an esterase is a class of enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis (and as such, it is a type of hydrolase). A wide range of different esterases exist that differ ...

enzymes.Hespell & O'Bryan-Shah, 1988Lin & Thomson, 1991 The induction of

xylanase Endo-1,4-β-xylanase (, systematic name 4-β-D-xylan xylanohydrolase) is any of a class of enzymes that degrade the linear polysaccharide xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls: : En ...

enzymes varies between strains; in group D1 strains (49, H17c, 12) xylanase expression appears to be

constitutively expressed Gene expression is the process (including its regulation) by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, proteins or non-coding RNA, and ultimately affect a pheno ...

, while groups B1 (113) and C (CF3) are induced only by growth on xylan, and those of group B2 are induced by growth on xylan or

arabinose Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. Properties For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, o ...

.Hespell & Whitehead, 1990 A number of genes encoding

glycoside hydrolase In biochemistry, glycoside hydrolases (also called glycosidases or glycosyl hydrolases) are a class of enzymes which catalysis, catalyze the hydrolysis of glycosidic bonds in polysaccharide, complex sugars. They are extremely common enzymes, wi ...

s (GH) have been identified in ''Butyrivibrio'' species including endocellulase (GH family 5 and 9); β-Glucosidase (GH family 3); endoxylanase (GH family 10 and 11); β-Xylosidase (GH family 43); and α-Amylase (GH family 13) enzymes. Several carbohydrate binding modules (CBM) have also been identified that are predicted to bind

glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body. Glycogen functions as one of three regularly used forms ...

(CBM family 48); xylan or

chitin Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...

(CBM family 2); and starch (CBM family 26).Krause et al., 2003Cantarel et al., 2008

Strains

The genus ''Butyrivibrio'' encompasses over 60 strains that were originally confined to the species ''

Butyrivibrio fibrisolvens ''Butyrivibrio'' is a genus of bacteria in Class Clostridia. Bacteria of this genus are common in the gastrointestinal systems of many animals. Genus ''Butyrivibrio'' was first described by Bryant and Small (1956) as anaerobic, butyric acid-pr ...

'' based on their

phenotypic In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...

and metabolic characteristics. However,

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

based on 16S

ribosomal RNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ...

(rRNA) gene sequences has divided the genus ''Butyrivibrio'' into six families.Kopecny et al., 2003 (fig. 1.1) These families include the rumen isolates ''Butyrivibrio fibrisolvens'', ''B. hungateii'', ''B. proteoclasticus'', ''Pseudobutyrivibrio xylanivorans'', and ''P. ruminis'' and the human isolate ''B. crossotus''. The families ''B. fibrisolvens'', ''B. crossotus'', ''B. hungateii'' as well as ''B. proteoclasticus'' all belong to the ''

Clostridium ''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tracts of animals, including humans. This genus includes several significant human pathogens, including the causative ...

'' sub-cluster XIVa.Willems et al., 1996

Phylogeny

The currently accepted taxonomy is based on the

List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclatu ...

(LPSN) and

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is lo ...

(NCBI)

Metabolism

Strains

Phylogeny

See also

References

Further reading