Potential of ochratoxin A production byAspergillus carbonariusstrains isolated from grapes at different ecological factors

Abstract

Aspergillus carbonarius is known to colonize and produce ochratoxin A (OTA) on grapes and its derived products which is harmful to humans. We screened and tested A. carbonarius strains which isolated from grapes for production of OTA and selected three high OTA producing strains (ACSP1, ACSP2, ACSP3) for this study. These strains were further tested for their ability to produce OTA at different ecological factors [temperature 15, 25, 30, 358C; water activity (a w ) 0.98, 0.95, 0.90, 0.88; and pH 4.0, 7.0, 9.0, 10.0]. Out of the three strains tested, A. carbonarius ACSP3 produced high levels of OTA than ACSP2 and ACSP1 in all the ecological factors. At 308C A. carbonarius strains produced the highest OTA compared with other temperature regimes. With reference to water activity, a w 0.98 favoured mycelial growth and accumulation of more OTA with all the three A. carbonarius strains. Further, pH 4.0 was encouraged the greatest production of OTA in all the strains. No growth was observed at a w 0.88 and pH 10.0 in all the three strains except the strain ACSP3 at high pH. Our work demonstrated that temperature 308C, a w 0.98 and pH 4.0 is optimum for growth and production of OTA by A. carbonarius strains. Maximum amounts of OTA were found at earlier growth stages (7-9 days of incubation) in all the strains of A. carbonarius. The present study revealed that different ecological factors had great impact on OTA production by A. carbonarius which is useful for understanding OTA contamination and to develop proper management practices in future research programmes.

Modelling the influence of temperature, water activity and sodium metabisulphite on the growth and OTA production of Aspergillus carbonarius isolated from Greek wine grapes

“…Our results are in good agreement with previous works reporting 30 C and 0.960e0.985 a w as optimum conditions of temperature and water activity, respectively, in the absence of antifungal agents (Mitchell et al, 2004;Tassou et al, 2007;Patharajan et al, 2011). Moreover, our findings are in line with Lasram et al (2010) who reported a significant decrease of A. carbonarius growth when temperature increased over 37 C. Pateraki et al (2007) after assessing the germination of five A. carbonarius strains under different a w levels and NaMBS Fig.…”

“…Moreover, Astoreca et al (2007) reported that the highest OTA amounts were measured at 30 C/0.99 a w when assessing two A. carbonarius strains isolated from dried grapes. The highest levels of OTA were found at 0.98 a w and decreased when a w decreased as reported by other researchers as well (Mitchell et al, 2004;Bellí et al, 2005;Medina et al, 2007;Lasram et al, 2010;Patharajan et al, 2011). After treatment with NaMBS, results showed that OTA content was enhanced even in the cases where fungal growth was delayed by the presence of the antifungal agent.…”

Study on the effect of physical, chemical and biotic factors on growth and ochratoxin A production of black aspergilli isolated from greek vineyards

“…Our results are in good agreement with previous works reporting 30 °C and 0.960-0.985 a w as optimum conditions of temperature and water activity, respectively, in the absence of antifungal agents (Mitchell et al, 2004;Tassou et al, 2007b;Patharajan et al, 2011). Moreover, our findings are in line with Lasram et al (2010) who reported a significant decrease of A. carbonarius growth when temperature increased over 37 °C.…”

“…at 30 °C/0.99 a w when assessing two A. carbonarius strains isolated from dried grapes. The highest levels of OTA were found at 0.98 a w and decreased when a w decreased as reported by other researchers as well (Mitchell et al, 2004;Bellí et al, 2005b;Medina et al, 2007a;Lasram et al, 2010;Patharajan et al, 2011).…”

“…The statistical analysis showed that all single factors and the interaction of NaMBS with temperature had significant effects on OTA accumulation (p < 0.05) (Table 2). Patharajan et al (2011) also reported conditions of 30 °C and 0.98 a w as optimum for OTA production, followed by 25 °C and 35 °C, but not within the range of 15-20 °C that is usually reported by other researchers (Mitchell et al, 2004;Bellí et al, 2005b;Leong et al, 2006b;Lasram et al, 2010). Esteban et al (2006b) )…”