Mateo Eva M, Gómez José Vicente, Gimeno-Adelantado José Vicente, Romera David, Mateo-Castro Rufino, Jiménez Misericordia
a Microbiology and Ecology Department , University of Valencia , Valencia , Spain.
b Analytical Chemistry Department , University of Valencia , Valencia , Spain.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2017 Jun;34(6):1039-1051. doi: 10.1080/19440049.2017.1310400. Epub 2017 May 17.
Aspergillus flavus is a highly aflatoxin (AF)-producing species infecting maize and other crops. It is dominant in tropical regions, but it is also considered an emerging problem associated with climate change in Europe. The aim of this study was to assess the efficacy of azole fungicides (prochloraz, tebuconazole and a 2:1 (w/w) mixture of prochloraz plus tebuconazole) to control the growth of A. flavus and AF production in yeast-extract-sucrose (YES) agar and in maize kernels under different water activities (a) and temperatures. Aflatoxins B and B were determined by LC with fluorescence detection and post-column derivatisation of AFB. In YES medium and maize grains inoculated with conidia of A. flavus, the growth rate (GR) of the fungus and AFB and AFB production were significantly influenced by temperature and treatment. In YES medium and maize kernels, optimal temperatures for GR and AF production were 37 and 25°C, respectively. In maize kernels, spore germination was not detected at the combination 37ºC/0.95 a; however, under these conditions germination was found in YES medium. All fungicides were more effective at 0.99 than 0.95 a, and at 37 than 25ºC. Fungicides effectiveness was prochloraz > prochloraz plus tebuconazole (2:1) > tebuconazole. AFs were not detected in cultures containing the highest fungicide doses, and only very low AF levels were found in cultures containing 0.1 mg l prochloraz or 5.0 mg l tebuconazole. Azoles proved to be highly efficient in reducing A. flavus growth and AF production, although stimulation of AF production was found under particular conditions and low-dosage treatments. Maize kernels were a more favourable substrate for AF biosynthesis than YES medium. This paper is the first comparative study on the effects of different azole formulations against A. flavus and AF production in a semi-synthetic medium and in maize grain under different environmental conditions.
黄曲霉是一种能产生大量黄曲霉毒素（AF）的菌种，可感染玉米和其他作物。它在热带地区占主导地位，但在欧洲也被视为与气候变化相关的一个新出现的问题。本研究的目的是评估唑类杀菌剂（咪鲜胺、戊唑醇以及咪鲜胺与戊唑醇按2:1（w/w）比例混合的药剂）在不同水分活度（a）和温度条件下，对酵母提取物蔗糖（YES）琼脂以及玉米粒中黄曲霉生长和黄曲霉毒素产生的控制效果。黄曲霉毒素B1和B2通过液相色谱法结合荧光检测以及黄曲霉毒素B1的柱后衍生化来测定。在接种了黄曲霉分生孢子的YES培养基和玉米粒中，真菌的生长速率（GR）以及黄曲霉毒素B1和B2的产生受到温度和处理方式的显著影响。在YES培养基和玉米粒中，生长速率和黄曲霉毒素产生的最佳温度分别为37℃和25℃。在玉米粒中，37℃/0.95 a的条件下未检测到孢子萌发；然而，在这些条件下，在YES培养基中发现了萌发现象。所有杀菌剂在水分活度0.99时比0.95 a时更有效，在37℃时比25℃时更有效。杀菌剂的效果为咪鲜胺>咪鲜胺加戊唑醇（2:1）>戊唑醇。在含有最高杀菌剂剂量的培养物中未检测到黄曲霉毒素，在含有0.1 mg/L咪鲜胺或5.0 mg/L戊唑醇的培养物中仅发现极低水平的黄曲霉毒素。尽管在特定条件和低剂量处理下发现了黄曲霉毒素产生的刺激现象，但唑类在减少黄曲霉生长和黄曲霉毒素产生方面被证明是非常有效的。玉米粒是比YES培养基更有利于黄曲霉毒素生物合成的底物。本文是关于不同唑类制剂在不同环境条件下对半合成培养基和玉米粒中黄曲霉及黄曲霉毒素产生影响的首次比较研究。
