Butyrivibrio
Encyclopedia
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-producing
, curved rods
(or vibroids). Butyrivibrio cells are small, typically 0.4 – 0.6 µm
by 2 – 5 µm. They are motile
, using a single polar or subpolar monotrichous flagellum
. 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, their cell wall
s contain derivatives of teichoic acid
, and electron microscopy indicates that bacteria of this genus have a Gram-positive cell wall type. 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
s of ruminant
animals such as cows, deer
and sheep, where they are involved in a number of ruminal functions of agricultural
importance in addition to butyrate
production. These include fibre degradation, protein breakdown
, biohydrogenation
of lipid
s and the production of microbial inhibitors. Of particular importance to ruminant digestion, and therefore productivity, is their contribution to the degradation of plant structural carbohydrates, principally hemicellulose
.
Butyrivibrio species are metabolically versatile and are able to ferment
a wide range of sugar
s and cellodextrins. Some strains have been reported to break down cellulose
, although their ability to sustain growth on cellulose appears to be lost during in vitro culturing
. Most isolates are amylolytic
and are able to degrade xylan
by producing xylanolytic and esterase
enzymes. The induction of xylanase
enzymes varies between strains; in group D1 strains (49, H17c, 12) xylanase expression appears to be constitutively expressed
, 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
.
A number of genes encoding glycoside hydrolase
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
(CBM family 48); xylan or chitin
(CBM family 2); and starch (CBM family 26).
The Butyrivibrio genus encompasses over 60 strains that were originally confined to the species Butyrivibrio fibrisolvens based on their phenotypic
and metabolic characteristics. However, phylogenetic analyses
based on 16S ribosomal RNA
(rRNA) gene sequences has divided the genus Butyrivibrio into six families. 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
sub-cluster XIVa.
. It was first isolated and described by Attwood et al. (1996), and was originally assigned to the genus Clostridium based on its similarity to Clostridium aminophilum, a member of the Clostridium sub-cluster XIVa. Further analysis has shown that it is more appropriately placed within the genus Butyrivibrio and the organism was given its current name. Within this genus its 16S rDNA sequence is most similar to, but distinct from, that of B. hungateii.
B. proteoclasticus is found in rumen contents at significant concentrations of from 2.01 x 106/ml to 3.12 x 107/mL as estimated by competitive PCR or 2.2% to 9.4% of the total eubacterial DNA within the rumen, as estimated by real time PCR. B. proteoclasticus cells are anaerobic, slightly curved rods, commonly found singly or in short chains, but it is not unusual for them to form long chains. They possess a single sub-terminal flagellum, but unlike other Butyrivibrio species, they are not motile. They are ultrastructurally Gram-positive, although as with all Butyrivibrio species, they stain Gram-negative
B. proteoclasticus has been shown to have an important role in biohydrogenation, converting linoleic acid
to stearic acid
.
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
in Class Clostridia
Clostridia
The Clostridia are a class of Firmicutes, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the genus Clostridium are all Gram-positive and have the ability to...
. 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
Anaerobic organism
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...
, butyric acid-producing
Butyric acid
Butyric acid , also known under the systematic name butanoic acid, is a carboxylic acid with the structural formula CH3CH2CH2-COOH. Salts and esters of butyric acid are known as butyrates or butanoates...
, curved rods
Bacillus (shape)
The word bacillus may be used to describe any rod-shaped bacterium, and such bacilli are found in many different taxonomic groups of bacteria. However, the name Bacillus, capitalized and italicized, refers to a specific genus of bacteria...
(or vibroids). Butyrivibrio cells are small, typically 0.4 – 0.6 µm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
by 2 – 5 µm. They are motile
Motility
Motility is a biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. Most animals are motile but the term applies to single-celled and simple multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs, in...
, using a single polar or subpolar monotrichous flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
. 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, their cell wall
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...
s contain derivatives of teichoic acid
Teichoic acid
Teichoic acids are bacterial polysaccharides of glycerol phosphate or ribitol phosphate linked via phosphodiester bonds.-Location and structure:...
, and electron microscopy indicates that bacteria of this genus have a Gram-positive cell wall type. It is thought that they appear Gram-negative when Gram stained because their cell walls thin to 12 to 18 nm
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
as they reach stationary phase
Bacterial growth
250px|right|thumb|Growth is shown as L = log where numbers is the number of colony forming units per ml, versus T Bacterial growth is the division of one bacterium into two daughter cells in a process called binary fission. Providing no mutational event occurs the resulting daughter cells are...
.
Butyrivibrio species are common in the rumen
Rumen
The rumen, also known as a paunch, forms the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. It serves as the primary site for microbial fermentation of ingested feed...
s of ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
animals such as cows, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
and sheep, where they are involved in a number of ruminal functions of agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
importance in addition to butyrate
Butyrate
Butyrate is the traditional name for the conjugate base of butanoic acid . The formula of the butanoate ion is C4H7O2-. The archaic name is used as part of the name of butyrates or butanoates, or esters and salts of butyric acid, a short chain fatty acid...
production. These include fibre degradation, protein breakdown
Protein catabolism
Protein catabolism is the breakdown of proteins into amino acids and simple derivative compounds, for transport into the cell through the plasma membrane and ultimately for the polymerisation into new proteins via the use of ribonucleic acids and ribosomes...
, biohydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...
of lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s and the production of microbial inhibitors. Of particular importance to ruminant digestion, and therefore productivity, is their contribution to the degradation of plant structural carbohydrates, principally hemicellulose
Hemicellulose
A hemicellulose is any of several heteropolymers , such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
.
Butyrivibrio species are metabolically versatile and are able to ferment
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
a wide range of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s and cellodextrins. Some strains have been reported to break down cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
, although their ability to sustain growth on cellulose appears to be lost during in vitro culturing
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
. Most isolates are amylolytic
Amylolytic process
Amylolysis, or the amylolytic process, is the conversion of starch into sugar by the action of acids or enzymes like amylase.The amylolytic process is used in the brewing of alcohol from grains. Since grains contain starches but little to no simple sugars, the sugar needed to produce alcohol is...
and are able to degrade xylan
Xylan
Xylan is a generic term used to describe a wide variety of highly complex polysaccharides that are found in plant cell walls and some algae. Xylans are polysaccharides made from units of xylose ....
by producing xylanolytic and esterase
Esterase
An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis.A wide range of different esterases exist that differ in their substrate specificity, their protein structure, and their biological function.- EC classification/list...
enzymes. The induction of xylanase
Xylanase
Xylanase is the name given to a class of enzymes which degrade the linear polysaccharide beta-1,4-xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls....
enzymes varies between strains; in group D1 strains (49, H17c, 12) xylanase expression appears to be constitutively expressed
Glossary of gene expression terms
See also: gene expression, List of Glossaries, List of Natural Sciences Glossaries-A:*Activator - protein that binds to an enhancer and activates transcription from nearby promoter....
, 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
Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde functional group.For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, or structurally analogous to D-glyceraldehyde.For sugars, the D/L...
.
A number of genes encoding glycoside hydrolase
Glycoside hydrolase
Glycoside hydrolases catalyze the hydrolysis of the glycosidic linkage to release smaller sugars...
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
Alpha-Amylase
α-Amylase is an enzyme that hydrolyses alpha-bonds of large alpha-linked polysaccharides such as starch and glycogen, yielding glucose and maltose. It is the major form of amylase found in humans and other mammals...
(GH family 13) enzymes. Several carbohydrate binding modules
Carbohydrate-binding module
In molecular biology, a carbohydrate-binding module is a protein domain found in carbohydrate-active enzymes . The majority of these domains have carbohydrate-binding activity. Some of these domains are found on cellulosomal scaffoldin proteins. CBMs were previously known as cellulose-binding...
(CBM) have also been identified that are predicted to bind glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
(CBM family 48); xylan or chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...
(CBM family 2); and starch (CBM family 26).
The Butyrivibrio genus encompasses over 60 strains that were originally confined to the species Butyrivibrio fibrisolvens based on their phenotypic
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
and metabolic characteristics. However, phylogenetic analyses
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
based on 16S ribosomal RNA
Ribosomal RNA
Ribosomal ribonucleic acid is the RNA component of the ribosome, the enzyme that is the site of protein synthesis in all living cells. Ribosomal RNA provides a mechanism for decoding mRNA into amino acids and interacts with tRNAs during translation by providing peptidyl transferase activity...
(rRNA) gene sequences has divided the genus Butyrivibrio into six families. 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
Clostridium is a genus of Gram-positive bacteria, belonging to the Firmicutes. They are obligate anaerobes capable of producing endospores. Individual cells are rod-shaped, which gives them their name, from the Greek kloster or spindle...
sub-cluster XIVa.
Butyrivibrio proteoclasticus B316T
Butyrivibrio proteoclasticus B316T was the first Butyrivibrio species to have its genome sequencedFull genome sequencing
Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...
. It was first isolated and described by Attwood et al. (1996), and was originally assigned to the genus Clostridium based on its similarity to Clostridium aminophilum, a member of the Clostridium sub-cluster XIVa. Further analysis has shown that it is more appropriately placed within the genus Butyrivibrio and the organism was given its current name. Within this genus its 16S rDNA sequence is most similar to, but distinct from, that of B. hungateii.
B. proteoclasticus is found in rumen contents at significant concentrations of from 2.01 x 106/ml to 3.12 x 107/mL as estimated by competitive PCR or 2.2% to 9.4% of the total eubacterial DNA within the rumen, as estimated by real time PCR. B. proteoclasticus cells are anaerobic, slightly curved rods, commonly found singly or in short chains, but it is not unusual for them to form long chains. They possess a single sub-terminal flagellum, but unlike other Butyrivibrio species, they are not motile. They are ultrastructurally Gram-positive, although as with all Butyrivibrio species, they stain Gram-negative
B. proteoclasticus has been shown to have an important role in biohydrogenation, converting linoleic acid
Linoleic acid
Linoleic acid is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2...
to stearic acid
Stearic acid
Stearic acid is the saturated fatty acid with an 18 carbon chain and has the IUPAC name octadecanoic acid. It is a waxy solid, and its chemical formula is CH316CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates...
.