Food Technology Department, Lleida University, XaRTA-TPV, Rovira Roure 191, 25198 Lleida, Spain.
Int J Food Microbiol. 2011 Jan 5;144(3):432-9. doi: 10.1016/j.ijfoodmicro.2010.10.030. Epub 2010 Oct 29.
The aim of this study was to assess the impact of suboptimal environmental conditions on the intraspecific variability of A. carbonarius growth and OTA production using thirty isolates of A. carbonarius. Three a(w)/temperature conditions were tested, one optimal (0.98a(w)/25°C) and two suboptimal: 0.90a(w)/25°C and 0.98a(w)/37°C as suboptimal water activity and temperature, respectively, which might take place through over ripening and dehydration of grapes. For each condition, 12 Petri dishes were inoculated, and colony growth and OTA production were measured over time. ANOVA revealed significant differences among μ and λ within the 30 assayed isolates. Coefficients of variation (CV%) revealed a wider dispersion of growth rates at 0.90a(w)/25°C compared to 0.98a(w)/25°C, and a more than 4-fold higher CV at 0.98a(w)/37°C compared to 0.98a(w)/25°C. However, dispersion of lag phases was similar at 0.98a(w)/25°C and 0.90a(w)/25°C and wider at 0.98a(w)/37°C. There were significant differences (p<0.05) among OTA levels (ng/mm(2)) for the different conditions, values being lower under marginal conditions, and particularly at 0.98a(w)/37°C. Coefficients of variation (CV%) revealed a wider dispersion of OTA production at 0.90a(w)/25°C compared to 0.98a(w)/25°C, while CV at 0.98a(w)/37°C was similar to that at 0.98a(w)/25°C. In order to address the strain variability in growth initiation and prove the well-established notion of reducing OTA in foods by preventing fungal growth, a greater number of strains should be included when developing models for conditions that are suboptimal both for a(w) for OTA production and temperature levels for growth.
本研究旨在评估环境条件不理想对 A. carbonarius 生长和 OTA 产生的种内变异性的影响，为此使用了 30 株 A. carbonarius 的分离株。测试了三种 a(w)/温度条件，一种是最佳条件（0.98a(w)/25°C），另外两种是次优条件：0.90a(w)/25°C 和 0.98a(w)/37°C，分别代表葡萄过熟和脱水时可能出现的低水分活度和温度。对于每种条件，在 12 个培养皿中进行接种，并随着时间的推移测量菌落生长和 OTA 产生情况。方差分析显示，在所测试的 30 个分离株中，μ 和 λ 之间存在显著差异。变异系数（CV%）显示，在 0.90a(w)/25°C 条件下，生长速率的分散度比在 0.98a(w)/25°C 条件下更宽，而在 0.98a(w)/37°C 条件下的分散度比在 0.98a(w)/25°C 条件下高出 4 倍以上。然而，在 0.98a(w)/25°C 和 0.90a(w)/25°C 条件下，滞后期的分散度相似，而在 0.98a(w)/37°C 条件下则更宽。不同条件下的 OTA 水平（ng/mm(2))之间存在显著差异（p<0.05），边缘条件下的数值较低，特别是在 0.98a(w)/37°C 条件下。变异系数（CV%）显示，在 0.90a(w)/25°C 条件下，OTA 产生的分散度比在 0.98a(w)/25°C 条件下更宽，而在 0.98a(w)/37°C 条件下的 CV 与在 0.98a(w)/25°C 条件下相似。为了研究生长起始时的菌株变异性，并证明通过防止真菌生长来减少食品中 OTA 的既定理念，在开发适用于 a(w)和 OTA 产生温度水平都不理想的条件的模型时，应纳入更多的菌株。
