Penicillium chrysogenum, also known as Penicillium notatum, was the first Penicillium species used for the isolation of penicillin antibiotics, which are effective in treating Gram-positive bacterial infections.
It is also utilized in the production of other β-lactam antibiotics.
The fungus is an allergen and possesses pathogenic activity, though it is uncommon as a cause of disease in humans.
Opportunistic infections caused by P. chrysogenum have been reported, particularly in immune-compromised individuals with underlying health conditions.
The genus name Penicillium originates from the Latin word meaning “painter’s brush,” referring to the fluffy appearance of its conidial spores.
Habitat of Penicillium chrysogenum
Penicillium chrysogenum is commonly found indoors, particularly in humid or damp areas and locations with standing or dumped water.
It is widespread in temperate and subtropical regions.
The fungus is present in moist soil and degraded forest vegetation.
Being saprophytic, it thrives on dead and decaying organic matter.
It can grow on stored food and damp building materials, making it a frequent indoor contaminant.
It has been found on alfalfa leafcutter bees and in subglacial ice, where it feeds on sediment-rich basal ice shelves.
The fungus can also colonize and cause decay in fruits.
Morphology of Penicillium chrysogenum
Penicillium chrysogenum reproduces by producing dry chains of spores called conidia, which arise from a thread-like, brush-shaped structure known as the conidiophore.
Under the microscope, it displays typical filamentous hyphae with conidia, which are the asexual spores of the fungus.
The hyphae are colorless, slender, tubular, branched, and septate.
These hyphae develop from multiple threads of mycelium, which can intertwine to form a hyphal network.
From this hyphal network, conidiophores arise as long, thick tubes with a swelling at the tip known as a vesicle.
The vesicles generate primary sterigmata, from which secondary sterigmata emerge.
The secondary sterigmata give rise to the conidial spores.
The conidia are typically long, cottony, or fluffy in texture.
Cultural characteristics of Penicillium chrysogenum
Colonies of Penicillium chrysogenum typically appear blue-green in color and produce a yellowish pigment.
Alexander Fleming described the fungus as initially forming a white, fluffy mass, which later turns green and eventually black.
After several days, a yellow pigment develops and diffuses throughout the culture medium.
Life Cycle of Penicillium chrysogenum
Penicillium chrysogenum reproduces asexually by producing asexual spores called conidia.
These conidial spores are dispersed through wind, water, or by animals.
Upon landing on a surface with suitable growth conditions and nutrient availability, the spores begin to germinate.
During germination, mycelial threads known as hyphae are formed.
From the hyphae, conidiophore tubes develop, ending in a bulged vesicle at the tip.
From these vesicles, primary sterigmata (also called phialides) arise.
The phialides subsequently produce the conidial spores, completing the cycle.
Pathogenesis of Penicilliun chrysogenum
Penicillium chrysogenum rarely causes disease, and when it does, the infections are typically opportunistic, occurring in individuals with severely suppressed immune systems, such as patients with HIV/AIDS.
The fungus exhibits very low pathogenicity, making its detection and identification in clinical infections uncommon.
Reported symptoms and conditions associated with its infections include:
Pulmonary infections such as pneumonia, localized granulomas, fungus balls, and systemic infections.
Systemic endophthalmitis, an inflammation of the ocular cavity.
Allergic reactions and asthma induction by triggering histamine release in the epithelial lining of the lungs, leading to asthmatic symptoms.
Treatment on Penicillium chrysogenum infection
Treatment involves surgical removal of the infection foci.
Oral antifungal medications such as amphotericin B and itraconazole are used.
For systemic endophthalmitis, topical amphotericin B or itraconazole is recommended.
Industrial Applications of Penicillium chrysogenum
Penicillium chrysogenum is widely utilized in antibiotic production, particularly for producing the hydrophobic β-lactam compound known as penicillin.
Penicillin is used to treat Gram-positive bacterial infections such as pneumonia, gonorrhea, wound infections, staphylococcal infections, and various bacterial fevers.
Structural variations of penicillin classify it into Penicillin G and Penicillin V.
Beyond medical applications, penicillin has been used in agriculture to treat crop diseases in apples, trees, grapes, and tomatoes, helping to induce protective mechanisms against infections.
Prevention and Control
Spray affected areas with water to minimize the spread of fungal spores into the air.
Clean walls using bleach and warm water to eliminate fungal growth.
References and Sources
Rob Dunn Lab. Penicillium chrysogenum – Invisible Life Project. Available at: http://robdunnlab.com/projects/invisible-life/penicillium-chrysogenum/
Botany Department, University of Wisconsin. Tom’s Fungi – November 2003: Penicillium chrysogenum. Available at: https://botit.botany.wisc.edu/toms_fungi/nov2003.html
MicrobeWiki, Kenyon College. Penicillium chrysogenum. Available at: https://microbewiki.kenyon.edu/index.php/Penicillium_chrysogenum
BUSTMOLD. Penicillium chrysogenum – Mold Library. Available at: https://www.bustmold.com/resources/mold-library/penicillium-chrysogenum/
Wikipedia. Penicillium chrysogenum. Available at: https://en.wikipedia.org/wiki/Penicillium_chrysogenum
