Osmotic and matric potential effects on growth, sugar alcohol and sugar accumulation by Aspergillus section Flavi strains from Argentina.
OBJECTIVE
The effect of osmotic and matric potential stress on growth and sugar alcohols (polyols: glycerol, erythritol, arabitol and mannitol) and sugars (trehalose and glucose) accumulation in toxigenic and nontoxigenic colonies of Aspergillus flavus and A. parasiticus was evaluated.


RESULTS
Growth of Aspergillus section Flavi with significant reductions at 20 and 30 degrees C was more sensitive to changes in matric potential, between 60 and 100% in the range of -7 to -14 MPa. No significant differences were found between toxigenic and nontoxigenic strains for both species. Total polyol accumulation in unamended maize meal agar medium (-0.75 MPa water potential) was higher at 30 than 20 degrees C. The major change in concentrations of endogenous sugars and total polyols was in matrically amended medium (with PEG 8000) at -7 and -10 MPa. Accumulation of glucose, arabitol, mannitol and erythritol content of A. flavus and A. parasiticus mycelial colonies was greater in normal unstressed maize meal agar medium (-0.75 Mpa) at 20 degrees C. This was modified by solute and matric stress.


CONCLUSIONS
The data showed relative sensitivity to osmotic and matric potential, and temperature, and the impact on growth rates, polyol and sugar accumulation in mycelia of A. flavus and A. parasiticus.


CONCLUSIONS
The matric potential effects on growth may be of particular importance for growth and survival in environments with low-matric potential stress. The tolerance of spoilage fungi such as Aspergillus section Flavi to such modifications could increase the potential for spoilage and mycotoxin production in such substrates. This knowledge is important for understanding the relative ecological fitness of these aflatoxigenic species and in the development of prevention strategies for their control.
Nesci
A
A
Departamento de Microbiologìa e Inmunología, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
Etcheverry
M
M
Magan
N
N
D001118:Argentina; D001230:Aspergillus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D050260:Carbohydrate Metabolism; D003470:Culture Media; D003681:Dehydration; D017753:Ecosystem; D004896:Erythritol / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D025282:Mycelium / Q000378:metabolism; D009995:Osmosis / Q000502:physiology; D012988:Soil Microbiology; D013402:Sugar Alcohols / Q000378:metabolism*; D013696:Temperature; D014199:Trehalose / Q000378:metabolism
D003470:Culture Media; D013402:Sugar Alcohols; D008353:Mannitol; D014199:Trehalose; D005947:Glucose; D005990:Glycerol; D004896:Erythritol; C014999:arabitol