Penicillium Sp.

Genus/species:  Penicillium Sp.

 

Classification:  Ascomycete; anamorph (Penicillium is often referred as Deuteromycetes)

Morphology:

  • Cell: Multicellular, elipsoid
  • Spore: Conidia; phialidies
  • Zygote: Reproduces asexually, no zygotes
  • Ascus: NA
  • Liquid Growth: pellicle, biofilm

Penicillum spp. are filamentous fungi. They have branched conidiospores. Conidia are round and unicellular. Penicillium reproduces asexually. Species are classified based on the way conidia are produced. In some species, conidia are born on phialidies. In others the conidiophore bears metullae, where phialidies are born. In other species, the conidiophore may branch out before bearing metullae.

Physiological Traits:

  • Saprophyte, nutrients out of dead & decayed substances
  • Penicillium mold inhibits bacterial biofilm formation in part by producing penicillic acid and patulin
  • Dry spores are easily spread through the air as well as carried by water
  • Toxin and allergenic compounds producer

Ecological Traits:

  • Ubiquitous
  • Soil, cereals, silage, breads, onions, garlic, cheese, nuts, fruits, and other foods
  • Lichens (made up of two different species: a fungus and either a cyanobacterium or a green algae)
  • Penicillium spp. strains are more abundant in temperate climatic regions

Distinguishing Features:

  • Penicillium spp. are initially white and become blue-green, gray-green, olive-gray, yellow or pinkish with time
  • Multicellular fungi are composed of filaments called hyphae
  • Hyphae may contain internal crosswalls, called septa, that divide the hyphae into separate cells
  • chitin/glucan wall
  • The spores (conidia) are produced in dry chains from the tips of the phialides, with the youngest spore at the base of the chain, and are nearly always green

Role in wine:

  • Massive negative impact on wine sensory
  • Potential increase in titratable acidity
  • Spores of Penicillium contain mycotoxins (patulin, citrinin, roquefortin, ochratoxin A – “OTA”) responsible for causing a variety of allergy symptoms and illnesses
  • OTA: The International Agency for Research on Cancer classified OTA in group 2B as a possible human carcinogen
  • Fungi  can  alter  the  chemical  composition of  the berries and affect the growth of yeasts during alcoholic fermentation  leading  to changes  in  the color and flavor of wine

Sensitivities:

  • SO2: X
  • Sorbate­­­­­: X
  • DMDC: X
  • pH: X
  • Acids:X
  • Ethanol: X
  • Anaerobiosis: No
  • Heat: > 55°C

References:

Torelli, E. et al, 2006. Ochratoxin A-producing strains of Penicillium spp. isolated from grapes used for the production of ‘‘passito’’ wines. International Journal of Food Microbiology 106 (2006) 307 – 312