Penicillium chrysogenum
Encyclopedia
Penicillium chrysogenum is common in temperate and subtropical regions and can be found on salted food products, but it is mostly found in indoor environments, especially in damp or waterdamaged buildings. It was previously known as Penicillium notatum. It has rarely been reported as a cause of human disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

. It is the source of several β-lactam antibiotic
Beta-lactam antibiotic
β-Lactam antibiotics are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in its molecular structure. This includes penicillin derivatives , cephalosporins , monobactams, and carbapenems...

s, most significantly penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

. Other secondary metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...

s of P. chrysogenum include various penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

s, roquefortine C
Roquefortine C
Roquefortin C is a mycotoxin produced by various fungi, particularly species from the Penicillium genus. It was first isolated from a strain of Penicillium roqueforti, a species commercially used to make Roquefort cheese.-References:*...

, meleagrin, chrysogine, xanthocillin
Xanthocillin
Xantocillin , also known as xanthocillin X or ophthocillin, was the first reported natural product found to contain the isocyanide functional group. It was first isolated from Penicillium notatum by Westling in 1950 and subsequently from several other sources....

s, secalonic acids, sorrentanone, sorbicillin, and PR-toxin.

Like the many other species of the genus Penicillium
Penicillium
Penicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body...

, P. chrysogenum reproduces by forming dry chains of spores (or conidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...

) from brush-shaped conidiophores. The conidia are typically carried by air currents to new colonisation sites. In P. chrysogenum the conidia are blue to blue-green, and the mold sometimes exudes a yellow pigment. However, P. chrysogenum cannot be identified based on colour alone. Observations of morphology and microscopic features are needed to confirm its identity.

The airborne spores of P. chrysogenum are important human allergens. Vacuolar and alkaline serine proteases have been implicated as the major allergenic proteins.

P. chrysogenum has been used industrially to produce penicillin and xanthocillin X, to treat pulp mill waste, and to produce the enzymes polyamine oxidase, phospho-gluconate dehydrogenase, and glucose oxidase.

Science and history

Penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

 was discovered in 1928 when Alexander Fleming's
Alexander Fleming
Sir Alexander Fleming was a Scottish biologist and pharmacologist. He wrote many articles on bacteriology, immunology, and chemotherapy...

 lab assistant left a window open overnight and had mold spores cover his Staphylococcus
Staphylococcus
Staphylococcus is a genus of Gram-positive bacteria. Under the microscope they appear round , and form in grape-like clusters....

bacteria
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...

l specimens in a petri dish
Petri dish
A Petri dish is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch...

. At first Fleming was very irritated at the contamination but as he was about to throw the specimens away, he noticed something interesting. He looked under the microscope at the bacteria surrounding the blue-green mold and noticed that many were dead or dying. This later turned out to have been due to the mold preventing the bacteria from making new cell walls and reproducing. He identified the mold as Penicillium notatum, which releases the antibiotic penicillin G into the medium. After this he did some testing on humans and animals and discovered that not only did it kill bacteria, but that it was suitable for use in humans and animals. However, the discovery did not attract much attention until the 1940s when Howard Florey, Norman Heatley
Norman Heatley
Norman George Heatley was a member of the team of Oxford University scientists who developed penicillin.He was born in Woodbridge, Suffolk, and as a boy was an enthusiastic sailor of a small boat on the River Deben; an experience which gave him a lifelong love of sailing...

 and Ernst Chain developed methods for mass production
Mass production
Mass production is the production of large amounts of standardized products, including and especially on assembly lines...

 and application in humans, incited by the urgent war-time need for antibacterial agents.
At this point, though the drug had shown success in treating numerous bacterial diseases, it was still so difficult to produce and so dilute that it was not feasible to produce quantities large enough for mass production, and so an effort was begun to find a strain of Penicillium with a higher rate of production of penicillin. Army pilots sent back soil from around the world to be tested for the right kind of mold. Even the people of Peoria, Illinois were told to bring in any molds that they found around their homes. It has also been said that the scientists working on this project kept an eye out for similar looking molds while grocery shopping or when they were cleaning around the kitchen especially their refrigerators. It was by these means that Penicillium chrysogenum was discovered, on a cantaloupe from a grocery store in Peoria, Illinois. The fungus isolated from this cantaloupe produced several hundred times as much penicillin as Fleming's original cultures of Penicillium notatum. Subcultures of this fungus were then irradiated with X-rays and UV rays in an attempt to cause a mutation in the fungus that would lead to an increase in penicillin yield. The effort was successful, and a mutant strain was produced and cultured which yielded more than a thousand times the penicillin of Fleming's original culture. This discovery, in combination with vastly improved methods of culturing the fungus based on the principle of aerating the culture medium, resulted in the ability to mass produce penicillin in quantities great enough for distribution and mass use in the Army in WWII.
The discovery of penicillin ushered in a new age of antibiotics derived from microorganisms. Penicillin is an antibiotic made by growing the mold Penicillium chrysogenum in a fermenter. The mold is grown in a liquid culture containing sugar and other nutrients (for example a source of nitrogen). As the mold grows, the sugar is used up and only starts to make penicillin after using up most of the nutrients for growth.

Genetics and evolution

The ability to produce penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

 appears to have evolved over thousands of years, and is shared with several other related fungi. It is believed to confer a selective advantage during competition with bacteria for food sources. However, some bacteria have developed the ability to survive penicillin exposure by producing penicillinase
Beta-lactamase
Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems . These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam...

s, enzymes that degrade penicillin. Penicillinase production is one mechanism by which bacteria can become penicillin resistant.

The principal genes responsible for producing penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

, pcbAB, pcbC and penDE are closely linked, forming a cluster on chromosome I. Some high-producing Penicillium chrysogenum strains used for the industrial production of penicillin have been shown to have multiple tandem copies of the penicillin gene cluster.

External links

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