Alonso V, Vergara L Díaz, Aminahuel C, Pereyra C, Pena G, Torres A, Dalcero A, Cavaglieri L
a Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales , Universidad Nacional de Río Cuarto , Río Cuarto , Córdoba , Argentina.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2015;32(2):236-44. doi: 10.1080/19440049.2014.996256. Epub 2015 Jan 19.
Environmental conditions play a key role in fungal development. During the silage production process, humidity, oxygen availability and pH vary among lactic-fermentation phases and among different silage sections. The aim of this work was to study the physiological behaviour of gliotoxicogenic Aspergillus fumigatus strains isolated from maize silage under simulated natural physicochemical conditions - different water activities (a(W)), temperatures (Tº), pH and oxygen pressure - on the growth parameters (growth rate and lag phase) and gliotoxin production. The silage was made with the harvested whole maize plant that was chopped and used for trench-type silo fabrication. Water activity and pH of the silage samples were determined. Total fungal counts were performed on Dichloran Rose Bengal Chloramphenicol agar and Dichloran 18% Glycerol agar. The morphological identification of A. fumigatus was performed with different culture media and at different growth temperature to observe microscopic and macroscopic characteristics. Gliotoxin production by A. fumigatus was determined by HPLC. All strains isolated were morphologically identified as A. fumigatus. Two A. fumigatus strains isolated from the silage samples were selected for the ecophysiological study (A. fumigatus sensu stricto RC031 and RC032). The results of this investigation showed that the fungus grows in the simulated natural physicochemical conditions of corn silage and produces gliotoxin. The study of the physiological behaviour of gliotoxigenic A. fumigatus under simulated environmental conditions allowed its behaviour to be predicted in silage and this will in future enable appropriate control strategies to be developed to prevent the spread of this fungus and toxin production that leads to impairment and reduced quality of silage.
环境条件在真菌发育中起着关键作用。在青贮饲料生产过程中，湿度、氧气供应和pH值在乳酸发酵阶段以及不同青贮饲料区域之间会有所变化。这项工作的目的是研究从玉米青贮饲料中分离出的产毒烟曲霉菌株在模拟自然物理化学条件下——不同水分活度（a(W)）、温度（Tº）、pH值和氧气压力——对生长参数（生长速率和延迟期）以及麦角硫因产生的生理行为。青贮饲料由收获的整株玉米制成，切碎后用于建造壕沟式青贮窖。测定了青贮饲料样品的水分活度和pH值。在孟加拉玫瑰氯霉素琼脂和18%甘油孟加拉琼脂上进行总真菌计数。使用不同的培养基并在不同的生长温度下对烟曲霉进行形态学鉴定，以观察微观和宏观特征。通过高效液相色谱法测定烟曲霉产生的麦角硫因。所有分离出的菌株在形态上均被鉴定为烟曲霉。从青贮饲料样品中分离出的两株烟曲霉菌株被选用于生态生理学研究（狭义烟曲霉RC031和RC032）。这项调查的结果表明，该真菌在玉米青贮饲料的模拟自然物理化学条件下生长并产生麦角硫因。对产毒烟曲霉在模拟环境条件下生理行为的研究使其在青贮饲料中的行为得以预测，这将在未来有助于制定适当的控制策略，以防止这种真菌的传播以及毒素产生，从而导致青贮饲料质量受损和下降。
