Abstract:

Aflatoxin produced by Aspergillus flavus TO has strong carcinogenesis. Aspergillus niger mutant, resulted from original Aspergillus niger infiltrated with N+ ion beams at dose of 90×2.6×1013 N+/cm2, was selected to suppress growth of Aspergillus flavus TO and favored to be applied in control of a secondly possible contamination in Aspergillus flavus-contaminated raw materials in ferment industry. Based on such experiments as cultivation of Aspergillus flavus TO and N+-infiltrated Aspergillus niger strains together, and cultivation of Aspergillus niger and Aspergillus flavus TO strains alone and together, the results showed that Aspergillus flavus TO strains are inhibited by both Aspergillus niger and N+-infiltrated Aspergillus niger strains, and the inhibition in the former is slight but that in the latter is almost complete. In addition, grey and slim mycelia in Aspergillus flavus TO strains are also shown in the cultivation together with N+-infiltrated Aspergillus niger strains. Moreover, extracts from media were also examined by aflatoxin fluorescence analysis. Relatively obvious signals are observed in the Aspergillus flavus TO group, faint signals in the Aspergillus niger group, but no signals in the N+-infiltrated Aspergillus niger strain group. In conclusion, the original Aspergillus niger strain exerts slight inhibition against Aspergillus flavus TO growth and makes the decline in synthesis of aflatoxin and related pigments, while the Aspergillus niger mutant strain shows significant inhibition against the growth of Aspergillus flavus TO strain compared with the control. Therefore, the Aspergillus niger mutant strain has the potential be introduced to alcohol industry to prevent from Aspergillus flavus TO contamination and ensure safety in the ferment ation process.

Key words: Aspergillus niger mutant strain, Aspergillus flavus-TO, inhibition