Penicillium

Penicillium is a genus of fungi. It is commonly called green or blue mould. It is saprophytic because it feeds on dead and decaying matter. It is found in soil, air, food, and damp places.

Penicillium includes more than 300 species. Many of them are very useful in medicine, food, and industry. Others may cause allergies or infections.

Classification of Penicillium

Penicillium belongs to the group of Ascomycetes. These fungi produce ascospores during sexual reproduction.

Domain	Eukaryota
Kingdom	Fungi
Phylum	Ascomycota
Class	Eurotiomycetes
Order	Eurotiales
Family	Trichocomaceae
Genus	Penicillium

The name Penicillium comes from a Latin word meaning "painter’s brush". It is because the conidia form a brush-like structure.

Structure of Penicillium

The Penicillium has a multicellular mycelium.
The Mycelium is made of long, branched hyphae.
The Hyphae are septate and have many nuclei.
The cell wall is made of chitin and β-glucans.
Some hyphae grow deep into the substratum to take in nutrients.
The food is stored as oil globules.
Conidiophores grow at the tips and form conidia (asexual spores).
Conidia are formed in basipetal order (youngest at the base).
Phialides are special cells that produce conidia.
Ascospores (sexual spores) are formed in ascocarps inside asci.

Reproduction in Penicillium

Penicillium reproduces by vegetative, asexual, and sexual methods.

Vegetative Reproduction

It occurs by fragmentation of the mycelium. Each fragment grows into a new fungus.

Asexual Reproduction

Asexual spores are called conidia. Conidiophores may be branched or unbranched. They end in metulae, which bear phialides. Phialides produce conidia by mitosis.

Conidia form in chains and get dispersed by wind. When conidia land on a moist surface, they germinate. A germ tube grows and forms new mycelium.

Sexual Reproduction

Sexual spores are called ascospores. Some species are homothallic, others are heterothallic. The male organ is antheridium, the female is ascogonium.

Ascogonium divides and forms many nuclei. Antheridium coils around ascogonium and fuses with it. The fusion of cytoplasm is called plasmogamy. This forms a dikaryon (two nuclei in one cell). After that, karyogamy (fusion of nuclei) happens.

A diploid zygote is formed. It undergoes meiosis and mitosis to form 8 ascospores. Ascospores are released and grow into new fungi.

Economic Importance of Penicillium

Penicillium is very important in medicine, food, and industry.

1. Antibiotics

Penicillin was first discovered in Penicillium notatum by Alexander Fleming in 1929, but industrial production mainly uses Penicillium chrysogenum.
Penicillin fights Gram-positive bacteria.
It works by breaking their cell walls.

2. Cheese Production

P. camemberti helps make Camembert and Brie cheese.
P. roqueforti is used to make Roquefort and blue cheese.

3. Organic Acids and Enzymes

Penicillium produces important organic acids such as citric acid, gluconic acid, and tartaric acid.
It also produces enzymes like amylase, protease, cellulase, and more.

4. Antifungal and Medical Uses

Some Penicillium species help make antifungal drugs.
Others help in making tumour-suppressing compounds.

5. Mycoremediation

Certain Penicillium species are used to remove pollution. They break down toxic chemicals in soil and water.

Harmful Effects of Penicillium

Some types of Penicillium make harmful toxins. These toxins may cause allergies and breathing troubles. Penicillium marneffei can damage lungs, kidneys, and spleen. Cheese factory workers might face skin or eye problems.

Common Species of Penicillium

Species Name	Uses / Characteristics
Penicillium notatum	They produce penicillin and are found on food, leather, and soil
Penicillium chrysogenum	Used in penicillin production and grows in damp places
Penicillium camemberti	Used in making Camembert and Brie cheese
Penicillium roqueforti	Used in making Roquefort and blue cheese. They are non-toxic
Penicillium claviforme	Has medical use; known for synnema-like structure
Penicillium echinulatum	They are found in moist areas and are used in antibiotic production
Penicillium glaucum	Used in cheese production and fermentation

Summary

Penicillium is a fungus commonly known as green or blue mould. It lives on dead matter and is found in soil, air, and damp places. It reproduces by vegetative, asexual, and sexual methods. Penicillium is used to make antibiotics, cheese, enzymes, and acids. Some species can cause allergies or infections in weak individuals.