Aspergillus flavus induced ear rots and subsequent contamination of maize (Zea mays L.) by aflatoxin is a serious food safety issue. As México is one of the countries with maize highest per capita consumption, exposure to aflatoxin represents a serious potential health problem. Use of beneficial organisms such as bacteria and fungi with antagonistic capabilities against A. flavus can be applied to minimize aflatoxin contamination of maize. In this work we evaluated the antifungal activity against A. flavus and the inhibition of aflatoxin production of three bacterial isolates (Brevundimonas sp, Chromobacterium sp and Stenotrophomonas sp.) and one basideomycete fungi strain (Pleurotus ostreatus). For the antagonism assays the bacterial and fungal strains were inoculated on PDA medium added with a 10% wheat straw extract 3 cm in distance opposite to pathogenic fungi and incubated at 25 ° C with a photoperiod of 12:12 during 7 and 25 days for bacteria and fungi respectively. The barrier between strains and fungi indicated antagonist interaction between them. Aflatoxin production was detected by fluorescence of agar medium under ultraviolet light. Bacterial strains had an inhibitory effect on A. flavus growth after three days and not aflatoxin production was detected. On the other hand for the assays with Plerurotus ostreatus, the A. flavus growth was slower than the control and fluorescence was detected from day 5 and particularly by contact between both fungi, reaching its maximum at day 11, after that it decreased gradually until day 25 were fluorescence was not detected.
Full conference title:
- MS 2017