| Summary: | We examined the resilience of strains of <i>Aspergillus westerdijkiae </i>in terms of growth and ochratoxin A (OTA) production in relation to: (a) two-way interacting climate-related abiotic factors of water activity (a<sub>w</sub>, 0.99–0.90) × temperature (25–37 °C) on green coffee and roasted coffee-based media; (b) three-way climate-related abiotic factors (temperature, 30 vs. 35 °C; water stress, 0.98–0.90 a<sub>w</sub>; CO<sub>2</sub>, 400 vs. 1000 ppm) on growth and OTA production on a 6% green coffee extract-based matrix; and (c) the effect of three-way climate-related abiotic factors on OTA production in stored green coffee beans. Four strains of <i>A. westerdijkiae</i> grew equally well on green or roasted coffee-based media with optimum 0.98 a<sub>w</sub> and 25–30 °C. Growth was significantly slower on roasted than green coffee-based media at 35 °C, regardless of a<sub>w</sub> level. Interestingly, on green coffee-based media OTA production was optimum at 0.98–0.95 a<sub>w</sub> and 30 °C. However, on roasted coffee-based media very little OTA was produced. Three-way climate-related abiotic factors were examined on two of these strains. These interacting factors significantly reduced growth of the <i>A. westerdijkiae</i> strains, especially at 35 °C × 1000 ppm CO<sub>2</sub> and all a<sub>w</sub> levels when compared to 30 °C. At 35 °C × 1000 ppm CO<sub>2</sub> there was some stimulation of OTA production by the two <i>A. westerdijkiae</i> strains, especially under water stress. In stored green coffee beans optimum OTA was produced at 0.95–0.97 a<sub>w/</sub>30 °C. In elevated CO<sub>2</sub> and 35 °C, OTA production was stimulated at 0.95–0.90 a<sub>w</sub>.
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