''Propionibacterium'' is a

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is ...

, anaerobic, rod-shaped 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 ...

named for their unique

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

: They are able to synthesize

propionic acid Propionic acid (, from the Greek language, Greek words πρῶτος : ''prōtos'', meaning "first", and πίων : ''píōn'', meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula . It is a ...

by using unusual transcarboxylase

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s. Its members are primarily facultative parasites and commensals of

human Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

s and other animals, living in and around the

sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial s ...

sebaceous gland A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in ...

s, and other areas of the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

. They are virtually ubiquitous and do not cause problems for most people, but propionibacteria have been implicated in

acne Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

and other skin conditions. One study found the ''Propionibacterium'' was the most prevalent human skin-associated genus of microorganisms. In ruminants, propionibacteria reduce nitrate to nontoxic nitrogen compounds. Members of the genus ''Propionibacterium'' are widely used in the production of vitamin B₁₂,

tetrapyrrole Tetrapyrroles are a class of chemical compounds that contain four pyrrole or pyrrole-like rings. The pyrrole/pyrrole derivatives are linked by ( or units), in either a linear or a cyclic fashion. Pyrroles are a five-atom ring with four carbon ...

compounds, and propionic acid, as well as in the

probiotics Probiotics are live microorganisms that provide health benefits when consumed, generally by improving or restoring the microbiota in the Gut microbiota, gut. Probiotics are considered GRAS, generally safe to consume, but may cause bacteria– ...

and cheese industries. The strain ''

Propionibacterium freudenreichii ''Propionibacterium freudenreichii'' is a gram-positive, Motility, non-motile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, Jarlsberg cheese, Leerdammer and Maasdam cheese. Its concentration in Swi ...

'' subsp. ''shermanii'' is used in

cheesemaking Cheesemaking (or caseiculture) is the craft of making cheese. The production of cheese, like many other food preservation processes, allows the nutritional and economic value of a food material, in this case milk, to be preserved in concentrate ...

to create CO₂ bubbles that become "

eyes An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

"—round holes in the cheese.

Pathology

''Propionibacterium'' ''spp.'' are commensal bacteria that can occasionally cause infectious diseases. The most studied of these infections is

acne vulgaris Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

, caused by ''Cutibacterium acnes'' (formerly ''

Propionibacterium acnes ''Cutibacterium acnes'' (''Propionibacterium acnes'') is the relatively slow-growing, typically aerotolerant anaerobic, gram-positive bacterium (rod) linked to the skin condition of acne; it can also cause chronic blepharitis and endophthalmit ...

)''. It is a chronic inflammatory disease caused by the blockage of pilosebaceous units causing inflammatory lesions, non-inflammatory lesions or a mixture of both on the face, neck and/or chest. Acne vulgaris cannot be defined as an infectious disease since the bacteria is found on a vast majority of individuals without causing lesions. ''C. acnes'' colonize the skin only under certain favorable conditions. In most cases, ''C. acnes'' get trapped under the comedones where they proliferate to form micro-comedones, not visible to the naked eye, which can later form structures such as closed comedones (white heads) and open comedones. These comedones can rupture, releasing the follicular material inside the dermis. The cause of this rupture was thought to be the indirect effect of fat metabolism by the bacteria, however it was later found that bacteria are directly involved in comedome rupturing by producing factors such as proteases, hyaluronidases and neuraminidases which might be involved in thinning of the epithelium. ''C. acnes'' can also produce immune factors such as proinflammatory cytokine inducing-factors and chemotactic factors, and can induce host complement pathways.

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).

References

{{Authority control Propionibacteriales Bacteria genera

Pathology

Phylogeny

See also

References