Penicillium roqueforti

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Penicillium roqueforti
Penicillium roqueforti on Roquefort cheese

Penicillium roqueforti on Roquefort cheese

Systematics
Class : Eurotiomycetes
Subclass : Eurotiomycetidae
Order : Eurotiales
Family : Trichocomaceae
Genre : Penicillium
Type : Penicillium roqueforti
Scientific name
Penicillium roqueforti
Thom

Penicillium roqueforti is a kind of fungi from the genus of the brush mold ( Penicillium ). It is a globally distributed saprobiont that lives mainly in dead, decomposing, organic matter.

The species is best known for its use in the production of blue cheese .

Penicillium roqueforti grows widely on spoiled food and can release mycotoxins to it.

sexuality

Brush mold ( Penicillium ) have a pleomorphic development cycle ; they have a sexual form ( teleomorph ) and an asexual form ( anamorph ). Many species, such as Penicillium roqueforti , belong to the so-called Fungi imperfecti , which means that it is not known whether they reproduce exclusively asexually or whether the phase of sexual reproduction has not yet been discovered. Only the asexual forms are as Penicillium called, at best known sexual forms get a different genus name, then in the usual scheme of the sac fungi (Ascomycota) in the family of Trichocomaceae is classified.

Of Penicillium roqueforti no sexual form is known. The following description therefore refers exclusively to the anamorphic. In the closely related species Penicillium psychrosexualis , however, a sexual form is known that forms celistothecia .

description

Penicillium roqueforti form lawns of fungi that grow in so-called colonies . The surface of these colonies is usually velvety. It is flat or smooth. The margin is wide, white and thin, still without conidia. It is cobweb-like or veil-like. Inwardly, irregularly nested, circular sections in which sporulation already takes place follow. The colonies are white on the outside, then with bluish circles, turning green towards the center with a dark center. The colonies initially consist of a dense network of hyphae called the mycelium . Exudation does not take place. The mushroom lawn hardly smells and when it does, it is slightly sour or musty.

During fructification , brush-like conidia carriers are formed, which are used for reproduction and on which conidiospores (conidia) mature. The conidiophores consist of a branched conidiophore and phialides . The term conidiophore is used inconsistently, however, and is occasionally used synonymously with the entire conidium carrier.

The conidiophore is almost cylindrical, grows perpendicular to the mycelium and is single or multiple, with long, adjacent or protruding branches, branched. It is mononematous, i.e. separated from the hyphae cells. It is comparatively short for Penicillium species and is between 100 and 150 micrometers high (rarely up to 200 micrometers) and measures between 4.0 and 6.0 micrometers. The wall is littered with incrustations and bumps. A metula with a rough surface develops at the tip , which is between 12 and 15 micrometers high and 3.5 to 4.5 micrometers in diameter. Several phialides spring from it.

The phialides measure 8 to 12 micrometers in length and 3.0 to 3.5 micrometers in diameter. The conidia are almost spherical or perfectly spherical. They are smooth-walled and dark green. They measure 3.5–5.0 micrometers (in extreme cases up to 8.0 micrometers) and are in long, tangled chains.

distribution

Penicillium roqueforti is found in the soil, on fruits in food and as spores in the air. The species prefers to thrive in moist soil, where it acts as a saprobiont to decompose dead plant parts.

Penicillium roqueforti is cosmopolitan , which means that the species can be found almost everywhere on earth. It has even been found in the subglacial ice below arctic glaciers. However, the species is rare in the tropics.

Penicillium roqueforti likes to thrive in various silages , such as corn silage and grass silage . It is the most common mold there.

use

Roquefort cheese

Penicillium roqueforti is mainly used in the production of blue cheese . For example, the cheeses Roquefort , Gorgonzola , Bavaria Blu , Bleu d'Auvergne and Blue Stilton are produced with the help of this type of mold.

The species became historically and is in part still bred on loaves of bread until these are completely streaked with mold. The dried, moldy bread is ground and dissolved in liquid. The suspension, which contains a lot of spores, is then introduced into the still unripe cheese.

While the cheese is ripening, the loaves must be repeatedly pierced with large metal needles so that oxygen can get inside and Penicillium roqueforti can flourish. This process is called pricking out .

As it grows in the cheese, the species releases various methyl ketones into the cheese, which are responsible for its flavor. Since the 1970s, these ketones have also been produced artificially in bioreactors and added to snacks or dressings as an artificial blue mold aroma.

Pathogenicity

Infections

Infections caused by Penicillium roqueforti are extremely rare and excluded in people with an intact immune system. In individual cases, however, aspergillosis-like infections of the lungs are said to have occurred .

Mycotoxins

Penicillium roqueforti often grows on foods and releases secondary metabolites to them, including toxic mycotoxins . The most commonly infected foods include nuts of all kinds, especially peanuts ( Arachis hypogaea ). However, Penicillium roqueforti can also grow on fruits or other foods .

The secondary metabolites released include:

In cheese, at least the PR toxin reacts with the amino acids in milk and is rendered harmless. The Roquefortine are present in Roquefort cheese . Even if, for example, Roquefortin C can be neurotoxic , Roquefort does not pose a threat. In addition, Penicillium roqueforti produces mycophenolic acid , which can act as an immunosuppressive agent.

Allergies

The allergenic potential of Penicillium roqueforti also seems to be significantly below that of other brush molds. Serious allergic reactions are almost exclusively known to workers involved in Roquefort production.

Systematics

Within the genus, the species is classified in the section Asymmetrica, subsection Velutina . The species around Penicillium casei are most similar in morphology .

A 2010 study that included molecular genetic methods found that Penicillium carneum is the sister taxon to Penicillium roqueforti . The species Penicillium psychrosexualis , of which the teleomorph is also known, is basal to the two species.

swell

Unless otherwise stated, the information in the Description chapter is taken from the source: Raper & Thom 1949. EPA 1997 was the main source for the Mycotoxins chapter, unless otherwise stated.

literature

  • Kenneth B. Raper, Charles Thom: A Manual of the Penicillia . Williams & Wilkins, Baltimore 1949, pp. 396-401 (English).
  • Jos Houbraken, Jens C. Frisvad, Robert A. Samson: Sex in Penicillium series Roqueforti . In: IMA Fungus . tape 1 , no. 2 , November 2010, p. 171-180 (English, pdf ).
  • John I. Pitt, Ailsa D. Hocking: Fungi and Food Spoilage . 3. Edition. Springer, Dordrecht 2009, ISBN 978-0-387-92206-5 , pp. 254–257 ( online in Google Book Search).

Web pages

Individual evidence

  1. ↑ Houbraken et al. 2010
  2. ↑ EPO 1997
  3. ↑ Silva Sonjak, Jens C. Frisvad, Nina Gunde-Cimerman: Penicillium Mycobiota in Arctic Subglacial Ice . In: Microbial Ecology . tape 52 , no. 2 , August 2006, p. 207-216 , JSTOR : 25153372 (English).
  4. ^ Pitt & Hocking 2009
  5. ↑ Horst Auerbach, Elisabeth Oldenburg, Friedrich Weissbach: Incidence of Penicillium roqueforti and roquefortine C in silages . In: Journal of the Science of Food and Agriculture . tape 76 , no. 4 , April 1998, pp. 565-572 , doi : 10.1002 / (SICI) 1097-0010 (199804) 76: 4 <565 :: AID-JSFA990> 3.0.CO; 2-6 (English).
  6. ^ ME Boysen, KG Jacobsson, J. Schnürer: Molecular identification of species from the Penicillium roqueforti group associated with spoiled animal feed . In: Applied and environmental microbiology . tape 66 , no. 4 , April 2000, pp. 1523-1526 , PMID 10742236 (English).
  7. ↑ Barry A. Law, Adnan Tamime (Ed.): Technology of Cheesemaking . 2nd Edition. Wiley-Blackwell, ISBN 978-1-4443-4789-0 (English, online in the Google book search).
  8. ↑ Patrick F. Fox: Cheese: Chemistry, Physics and Microbiology: Major Cheese Groups . tape 2 . Springer, 2001, ISBN 978-0-8342-1339-5 , pp. 124 ff . (English, online in the Google book search).
  9. ↑ Basantk. Dwivedi, John E. Kinsella: Continuous Production of Blue-Type Cheese Flavor by Submerged Fermentation of Penicillium roqueforti . In: Journal of Food Science . tape 39 , no. 3 , May 1974, p. 620–622 , doi : 10.1111 / j.1365-2621.1974.tb02963.x (English).
  10. ↑ JF Peberdy: Biology of Penicillium . In: Arnold L. Demain, Nadine A. Solomon (Eds.): Biology of Industrial Microorganisms . Benjamin-Cummings, San Franzisko 1985, ISBN 978-0-8053-2451-8 , pp. 407-431 .
  11. ↑ MycoBank
  12. ↑ JA Campbell, MJ Kryda, MW Trauhaff, JJ Marx Jr., RC Roberts: Cheese workers hypersensitivity pneumonitis . In: The American review of respiratory disease . tape 127 , no. 4 , 1983, p. 495-496 , PMID 6838056 .
  13. ↑ Houbraken et al. 2010