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Penicillium griseofulvum is a species of fungus within the genus of Penicillium which produces the compounds patulin, penifulvin A, cyclopiazonic acid , roquefortine C , shikimic acid, kojic acid and is a producer of the mycotoxin griseofulvin. Penicillium griseofulvum occurs on cereals and nuts, and has a wide distribution throughout the world.

History and taxonomy
Penicillium griseofulvum was discovered in Scotland in 1901, but the fungus has a distribution that spans all over the world. It has been valuable for the oral treatment of dermatomycoses and has also been used to treat fungal infections in plants and other animals, including humans. Penicillium griseofulvum is a species in the kingdom of Fungus within the subdivision of Pezizomycotina in the class of Trichocomaceae. P. griseofulvum is in the order Eurotiales and the genus Penicillium

Growth and morphology
Penicillium griseofulvum grows restrictedly, with colonies grown on CZ at 23-25 &deg;C for 10-14 days rarely exceeding 3 cm in diameter and exhibiting a light grey to grey-blue coloration. Although some contradictions exist with regards to reported coloration, colonies are often grey-blue but never dark blue. Growth is slightly slow for Penicillium, at a rate of 1.8-2 cm in seven days at 24 C on CzA. medium. It displays a range of textures, from velvety to granular growth.

Often observed as light greyish-green to yellow-green colonies, and the reverse or underside of the plate is reported to be pale yellow to orange-brown or red-brown in coloration. Conidia are ellipsoidal, smooth walled, and approximately 2.5-3.5 X 2.2-2.5 μm, rarely exceeding 3 μm in diameter. The conidial nucleus divides when the first germ tube is formed, with one conidium bound nucleus dividing up into two further nuclei which give rise to three further germ tubes for a total of three- to four-stage divergently branched conidiophores. Conidiosphore heads are very variable in length, smooth-walled, brownish colored and asymetrical. Heads consist of unusually short flask-shaped sterigmata (rarely exceeding 6 μm in length), short and stalky metulae (sometimes wedge-shaped, rarely exceeding 10 μm), and branches. A fruity door similar to the scent of strawberries is often produced by colonies of P. griseofulvum. Penicillium griseofulvum is unique in having very short phialides on highly branched conidiophores. . The metulae are 7-10 um long and are sometimes inflated apically. Phialides of P. griseofulvum are closely packed, and reported to be very short at 4.5-6.0 μm.

Physiology
Penicillium griseofulvum colonies grown on CzA are slow growing, and often clustered to synnematal in organization. Colonies have also been found to be intolerant to benomyl. Griseofulvin acts against dermatophytic fungi and its physiological effects in the body and specificity to dermatophytic fungi are not well characterized. It is poorly absorbed by the gastrointestinal tract and is active in skin deposits. More than 300 chemical derivatives of griseofulvin have been synthesized, one of which had excellent plant protecting properties but this n-propyl derivative was financially impractical when compared to other alternatives. Germination can occur anywhere within the range of 4-37 &deg;C. Growth temperature is in the optimal range of 23-30 &deg;C. P. griseofulvum is unable to grow at 37 &deg;C.

Habitat and ecology
Conditions for Penicillium griseofulvum are not highly specific and it grows in many places, at a depth of more than 40 cm. Although not commonly found on forest soils, it has been found under conifers and under shrub and steppe type vegetation, as well as heathland soils. It is also found on desert soils and arable soils, under corn and wheat species particularly. P. griseofulvum has been shown to grow in the stubble-mulched soil after wheat crops have been harvested. It can grow in citrus soils, saline soils, and has been discovered in a uranium mine, caves and in sewage. Colonies can occur on harvested pecans, wheat grain, and corn, as well as, but more rarely, in barely. P. griseofulvum has been found on vole and rabbit dung, as well as tunnels of gerbils and feathers of free-living birds. Penicillium griseofulvum affects plant growth because of its production of patulin. Often crops will be affected by fungal growth even after ploughing, and ploughing of plant remains has been shown to increase growth. The fungus has been reported to grow in Alaska, the British Isles, Germany, the USSR, France, Spain, Isreal, Somalia, Pakistan, India, Australia, Peru and Brazil.

P. griseofulvum generally inoculates on peanuts and cereals. It also grows on harvested pecans, wheat grain, and corn, and more rarely on barley. P. griseofulvum has been documented to grow on the rhizospheres of potatoes, tomatoes, groundnuts and corn, but does not grow in root-free soil that is adjacent to the rhizospheres of these food products. Some accounts of the fungus report it grows on refrigerated dough products. P. griseofulvum has been found to be a common colonizer of decaying gains and animal feed. Alfalfa grown during the winter season has been observed to increase the amount of growth on wheat rhizospheres grown in the following season.

Griseofulvin
Griseofulvin, a chemical present in P. griseofulvum, is regarded as a mycotoxin and is sometimes thought of as an antibiotic and fungicide. However, it is not as toxic to bacteria at it is effective in eradicating fungal infections, especially of the scalp. Griseofulvin is also produced by P. nigricans and P. janczewskii. It is one of the few treatments for skin infecting fungi, along with Amphotericin B and Nystatin produced by actinomyces. . Griseofulvin can be taken orally as a treatment for ringworm (dermatophytosis) infections on the skin and hair but has no effect on the mycosis of internal organs, and is progressively less effective on the lower parts of the body. . Fungal infections of the foot are not effected while scalp infections could be eradicated. Case studies of the use of griseofulvin are not extensive. A man suffering from scalp ringworm for 50 years was cured of the disease by taking griseofulvin. In addition, an eight year old girl with ringworm disease of the body, skin and hair improved with griseofulvin therapy.