Water and temperature relations of growth and ochratoxin A production by Aspergillus carbonarius strains from grapes in Europe and Israel

Abstract

Aims: This study investigated the in vitro effects of water activity (a w ; 0AE85-0AE987) and temperature (10-40°C) on growth and ochratoxin A (OTA) production by two strains of Aspergillus carbonarius isolated from wine grapes from three different European countries and Israel on a synthetic grape juice medium representative of mid-veraison (total of eight strains). Methods and Results: The synthetic grape juice medium was modified with glycerol or glucose and experiments carried out for up to 56 days for growth and 25 days for OTA production. The lag phase prior to growth, growth rates and ochratoxin production were quantified. Statistical comparisons were made of all factors and multiple regression analysis used to obtain surface response curves of a w · temperature for the eight strains and optimum growth and OTA production by A. carbonarius. The lag phase increased from <1 day at 25-35°C and 0AE98 a w to >20 days at marginal temperatures and water availabilities. Generally, most A. carbonarius strains grew optimally at 30-35°C, regardless of solute used to modify a w , with no growth at <15°C. The optimum a w for growth varied from 0AE93 to 0AE987 depending on the strain, with the widest a w tolerance at 25-30°C. There was no direct relationship among growth, environmental factors and country of origin of individual strains. Optimum conditions for OTA production varied with strain. Some strains produced optimal OTA at 15-20°C and 0AE95-98 a w . The maximum OTA produced after 10 days was about 0AE6-0AE7 lg g)1 , with a mean production over all eight strains of 0AE2 lg g)1at optimum environmental conditions. Conclusions: This work demonstrates that optimum conditions for OTA production are very different from those for growth. While growth rates differed significantly between strains, integration of the OTA production data suggests possible benefits for use of the information on a regional basis. Significance and Impact of the Study: Very little detailed information has previously been available on the ecology of A. carbonarius. This knowledge is critical in the development and prediction of the risk models of contamination of grapes and grape products by this species under fluctuating and interacting environmental parameters.

Ochratoxin A and Brewing Technology: A Review

“…These species, A. lacticoffeatus and A. sclerotioniger, need further investigations and are provisionally accepted in section Nigri. In addition, another Aspergillus species, A. alliaceus also named Petromyces alliaceus and isolated from onions 69 , has been previously reported as an OTA producer under laboratory conditions 79 . This species has been suspected of being responsible for the occasional OTA contamination in Californian figs 18,121 and Argentinean medicinal herbs 97 .…”

Redes neuronales y preprocesado de variables para modelos y sensores en bioingeniería

“…Los factores más significativos que influyen en la producción de micotoxinas por los hongos que habitualmente contaminan las cosechas agrícolas tanto durante su cultivo como en postcosecha son diversos [26,155,220,231,232,243,276,287,333]. Entre estos factores destacan:…”

“…Así, en relación con la temperatura ambiente existen especies fúngicas productoras de micotoxinas que se desarrollan mejor a temperaturas suaves o relativamente altas (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) o C) como A. carbonarius [25,190,231,243], mientras que otras están aclimatadas en zonas frías como Penicillium verrucosum (10-15 o C) [205]. Ambas especies producen ocratoxina A.…”

“…También ocurre, al igual que sucede con la temperatura, que los valores de a w más propicios para la producción de micotoxinas no suelen coincidir en general con los más favorables para el crecimiento fúngico [243].…”

“…La producción de OTA es dependiente de la temperatura, la a w , el tiempo, la presencia de fungicidas, la cepa del hongo, etc [26,190,213,243,333]. Según Llorens et al [202] el efecto de la temperatura sobre la producción de DON por F. graminearum y F. culmorum en maíz es muy significativo, consiguiéndose un mayor nivel de DON a 28 o C. El efecto de la humedad fue menos importante y no significativo.…”