title: Effect of water activity and temperature on competing abilities of common postharvest citrus fungi.
abstract: The effect of temperature (4-30 degrees C) and water activity (a(w), 0.995-0.90) on the 'in vitro' interactions between Penicillium digitatum, Penicillium italicum and Geotrichum candidum were evaluated. The effect of temperature on growth of green and blue mould decays and their interactions on wounded oranges was also studied. The major competing abilities were observed at optimal conditions of temperature and a(w) for growth (25 degrees C and 0.995 a(w)), and no differences between growth rates when the fungi were growing alone or paired were observed in the other studied conditions. P. italicum and G. candidum were able to reduce the growth rate of P. digitatum when it was growing paired 'in vitro', suggesting that inhibitory metabolites were produced. In the 'in vivo' assays, growth rates of green mould were higher than those of blue mould at any temperature studied. However, at 4 degrees C, P. italicum began its rot development 1 week before P. digitatum. When these two pathogens were inoculated into the same wound at 25 degrees C, blue mould was practically inhibited. The difference between the results obtained in 'in vitro' and 'in vivo' assays suggests that other factors could interact with fungi, favoring the development of one pathogen to the detriment of the others.
authors.affiliation: Postharvest Unit, CeRTA, Centre UdL-IRTA, 177 Rovira Roure Avenue, 25198 Lleida, Catalonia, Spain. pilar.plaza@irta.es
authors.forename: Pilar
authors.initials: P
authors.lastname: Plaza
authors.forename: Josep
authors.initials: J
authors.lastname: Usall
authors.forename: Neus
authors.initials: N
authors.lastname: Teixidó
authors.forename: Immaculada
authors.initials: I
authors.lastname: Viñas
mesh_terms: D002957:Citrus / Q000382:microbiology*; D018920:Coculture Techniques; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005848:Geotrichum / Q000254:growth & development*; D010407:Penicillium / Q000254:growth & development* / Q000502:physiology; D013696:Temperature; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water