title: Temperature, water activity and pH during conidia production affect the physiological state and germination time of Penicillium species.
abstract: Conidial germination and mycelial growth are generally studied with conidia produced under optimal conditions to increase conidial yield. Nonetheless, the physiological state of such conidia most likely differs from those involved in spoilage of naturally contaminated food. The present study aimed at investigating the impact of temperature, pH and water activity (aw) during production of conidia on the germination parameters and compatible solutes of conidia of Penicillium roqueforti and Penicillium expansum. Low temperature (5°C) and reduced aw(0.900 aw) during sporulation significantly reduced conidial germination times whereas the pH of the sporulation medium only had a slight effect at the tested values (2.5, 8.0). Conidia of P. roqueforti produced at 5°C germinated up to 45h earlier than those produced at 20°C. Conidia of P. roqueforti and P. expansum produced at 0.900 awgerminated respectively up to 8h and 3h earlier than conidia produced at 0.980 aw. Furthermore, trehalose and mannitol assessments suggested that earlier germination might be related to delayed conidial maturation even though no ultra-structural modifications were observed by transmission electron microscopy. Taken together, these results highlight the importance of considering environmental conditions during sporulation in mycological studies. The physiological state of fungal conidia should be taken into account to design challenge tests or predictive mycology studies. This knowledge may also be of interest to improve the germination capacity of fungal cultures commonly used in fermented foods.
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Nicolas
authors: N
authors: Nguyen Van Long
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Valérie
authors: V
authors: Vasseur
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, UMT Spore Risk, IUT Quimper, 6 rue de l'Université, 29334 Quimper, France.
authors: Louis
authors: L
authors: Coroller
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Philippe
authors: P
authors: Dantigny
authors: Plateforme Merimage, Station Biologique de Roscoff, CNRS-UPMC, Place Georges Teissier, CS90074, 29688 Roscoff, Cedex, France.
authors: Sophie
authors: S
authors: Le Panse
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Amélie
authors: A
authors: Weill
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
authors: Jérôme
authors: J
authors: Mounier
authors: Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France. Electronic address: karim.rigalma@univ-brest.fr.
authors: Karim
authors: K
authors: Rigalma
mesh_terms: D003080:Cold Temperature; D004777:Environment; D005506:Food Contamination / Q000032:analysis; D018525:Germination / Q000502:physiology*; D005947:Glucose / Q000032:analysis; D008353:Mannitol / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D025282:Mycelium / Q000254:growth & development*; D010407:Penicillium / Q000254:growth & development* / Q000378:metabolism*; D013172:Spores, Fungal / Q000254:growth & development*; D014199:Trehalose / Q000032:analysis; D014867:Water
chemical_list: D014867:Water; D008353:Mannitol; D014199:Trehalose; D005947:Glucose
keywords: Compatible solutes; Conidial germination; Penicillium expansum; Penicillium roqueforti; Predictive mycology; Sporulation