RESUMO
The effect of atmosphere containing 80% CO(2) and 20% O(2) on growth of Mucor plumbeus, Fusarium oxysporum, Byssochlamys fulva, Byssochlamys nivea, Penicillium commune, Penicillium roqueforti, Aspergillus flavus, Eurotium chevalieri and Xeromyces bisporus was investigated. Production of aflatoxin by A. flavus, patulin by B. nivea, roquefortine C by P. roqueforti, and cyclopiazonic acid by P. commune was also studied. Fungal growth was evaluated by three methods: colony diameter, hyphal length or mycelium dry weight and ergosterol content. Among the nine fungal species examined, two E. chevalieri and X. bisporus, did not grow under these conditions. In this study, fungi differed in their response to modified atmospheres in biomass, ergosterol content, mycotoxin production and morphology. Reductions of 57.8-96.9%, 73.7-99.6% and 91.5-99.9% were obtained in colony diameter, hyphal length and ergosterol content, respectively, under this atmosphere compared to air. Ergosterol content was more affected in most species than other measurements. Patulin, cyclopiazonic acid and roquefortine C were produced in this atmosphere, although levels were very low and aflatoxin was not produced at all. Growth was quite extensive as measured by colony diameters, but hyphal lengths were low and ergosterol production was also affected in all species of this study.
Assuntos
Atmosfera/química , Dióxido de Carbono/química , Fungos/metabolismo , Micotoxinas/biossíntese , Oxigênio/química , Dióxido de Carbono/farmacologia , Fungos/efeitos dos fármacos , Oxigênio/farmacologia , Fatores de TempoRESUMO
The influence of high carbon dioxide and low oxygen concentrations on growth by the foodborne fungal species, Mucor plumbeus, Fusarium oxysporum, Byssochlamys fulva, Byssochlamys nivea, Penicillium commune, Penicillium roqueforti, Aspergillus flavus, Eurotium chevalieri and Xeromyces bisporus was investigated. Production of aflatoxin by A. flavus, patulin by B. nivea and roquefortine C by P. roqueforti was also studied. Fungal growth was evaluated under atmospheres consisting of 20, 40 and 60% CO(2) plus <0.5% O(2), on two media, Czapek Yeast Extract agar and Potato Dextrose agar. Several methods for measuring fungal growth were used: colony diameter, ergosterol content, hyphal length and/or mycelium dry weight. Among the nine species, three groups were distinguished with respect to their growth responses under modified atmospheres: (i) species which did not grow in 20% CO(2) <0.5% O(2) (P. commune, E. chevalieri and X. bisporus); (ii) species which grew in 20% CO(2) <0.5% O(2), but not 40% CO(2) <0.5% O(2) (P. roqueforti and A. flavus); (iii) species which grew in 20%, 40% and 60% CO(2) <0.5% O(2) (M. plumbeus, F. oxysporum, B. fulva and B. nivea). Facultatively anaerobic behaviour was observed in these last four species, which grew under the same conditions as the obligate anaerobe, Clostridium sporogenes. The production of aflatoxin, patulin, and roquefortine C was greatly reduced under all of the atmospheres tested.
Assuntos
Dióxido de Carbono/farmacologia , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Fungos/crescimento & desenvolvimento , Fungos/metabolismo , Micotoxinas/biossíntese , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Relação Dose-Resposta a Droga , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Oxigênio/farmacologiaAssuntos
Ergosterol/análise , Microbiologia de Alimentos , Fungos/classificação , Fungos/isolamento & purificação , Hifas/fisiologia , Biomassa , Contagem de Colônia Microbiana , Meios de Cultura , Contaminação de Alimentos , Fungos/crescimento & desenvolvimento , Fungos/fisiologia , Especificidade da EspécieRESUMO
The use of modified atmospheres to prevent fungal growth and mycotoxin production in cheese was evaluated. Eight fungal species: Mucor plumbeus, Fusarium oxysporum, Byssochlamys fulva, B. nivea, Penicillium commune, P. roqueforti, Aspergillus flatus and Eurotium chevalieri were inoculated onto cheese and incubated under conditions of decreasing concentrations of O2 (5% to < 0.5%) and increasing concentrations of CO2 (20-40%). Fungal growth was measured by colony diameter and ergosterol content. All fungi examined grew in atmospheres containing 20% and 40% CO2 with 1% or 5% O2, but growth was reduced by 20-80%, depending on species, compared with growth in air. The formation of aflatoxins B1 and B2, roquerfortine C and cyclopiazonic acid was greatly decreased but not totally inhibited in these atmospheres. At 20% or 40% CO2 with < 0.5% O2, only B. nivea exhibited growth, which was very slow. Growth of F. oxysporum, B. fulca, P. commune and A. flavus showed good correlations between colony diameter and ergosterol content. However, for the other species correlations were inconsistent.