Al-Saad Labeed A, Al-Badran Adnan I, Al-Jumayli Sami A, Magan Naresh, Rodríguez Alicia
University of Basrah, College of sciences, Dept. of Biology, Iraq.
University of Karbala, College of Applied Medical Sciences, Iraq.
Int J Food Microbiol. 2016 Jan 18;217:123-9. doi: 10.1016/j.ijfoodmicro.2015.10.016. Epub 2015 Oct 19.
The objectives of this study were to examine the efficacy of four bacterial antagonists against Aspergillus flavus using 50:50 ratio of bacterial cells/conidia for the control of aflatoxin B1 (AFB1) production on two different nutritional matrices, nutrient and maize-based media at different water availabilities (0.98, 0.94 water activity (aw) on nutrient medium; 0.995, 0.98 aw on maize meal agar medium) at 35°C. The indicators of efficacy used were the relative expression of one structural and regulatory gene in the biosynthetic pathway (aflD and aflR respectively) and the production of AFB1. These studies showed that some of the bacterial species could significantly inhibit the relative expression of the aflD and aflR genes at both 0.98 and 0.94 aw on nutrient agar. On maize-based media some of the bacterial antagonists reduced the activity of both genes at 0.94 aw and some at 0.995 aw. However, the results for AFB1 production were not consistent with the effects on gene expression. Some bacterial species stimulated AFB1 production on both nutrient and maize-based media regardless of aw. However, some bacterial treatments did inhibit AFB1 production significantly when compared to the control. Overall, this study suggests that temporal studies are required on the biosynthetic genes under different environmental and nutritional conditions to evaluate the potential of antagonists to control AFB1.
本研究的目的是在35°C下，使用细菌细胞/分生孢子50:50的比例，检测四种细菌拮抗剂对黄曲霉的功效，以控制两种不同营养基质（营养培养基和玉米基培养基）在不同水分有效性（营养培养基上水分活度（aw）为0.98、0.94；玉米粉琼脂培养基上aw为0.995、0.98）时黄曲霉毒素B1（AFB1）的产生。所使用的功效指标是生物合成途径中一个结构基因和调控基因（分别为aflD和aflR）的相对表达以及AFB1的产生。这些研究表明，在营养琼脂上，aw为0.98和0.94时，一些细菌种类能显著抑制aflD和aflR基因的相对表达。在玉米基培养基上，一些细菌拮抗剂在aw为0.94时降低了两个基因的活性，一些在aw为0.995时降低了活性。然而，AFB1产生的结果与对基因表达的影响不一致。一些细菌种类在营养培养基和玉米基培养基上均刺激了AFB1的产生，而与aw无关。然而，与对照相比，一些细菌处理确实显著抑制了AFB1的产生。总体而言，本研究表明，需要在不同环境和营养条件下对生物合成基因进行时间研究，以评估拮抗剂控制AFB1的潜力。
