| Abstrakt: |
Aflatoxin B1 (AFB1), as the most mutagenic and carcinogenic mycotoxin, is commonly present in food worldwide and brings about serious health and economic problem to human. So far, no method could safely and effectively eliminate AFB1 contamination in food. To obtain an efficient strain with capability of inhibiting AFB1 biosynthesis and degrading AFB1 simultaneously, twenty strains of non-toxigenic Aspergillus spp. isolated from the Chinese soybean paste (including 6 of Aspergillus oryzae, 6 of Aspergillus niger, 5 of Aspergillus sojae and 3 of Aspergillus tamarii) were assessed in this research. Resuits showed that 17 strains could decrease the content of AFB1 produced by Aspergillus flavus with different degree (reduction percentage from 19.27% to 80.33%). But only Aspergillus niger and Aspergillus tamarii have the ability to degrade AFB1 (degradation percentage from 6.18% to 57.44%). Among these strains, Aspergillus niger (AN4) presented the strongest ability to control AFB1 contamination and was selected for further study. AFB1 was degraded from 1255.00±134.20 to 200.85±41.51 ng/ml by the culture filtrate of AN4. When the filtrate was supplemented with solid ammonium sulfate up to 80% saturation, the dissolved precipitate had the same AFBI biodegrability as the filtrate; however, the supernatant had lower biodegrability than the filtrate. It suggested that the substances responsible for the degradation of AFB1 are extracellular enzymes produced by AN4. Moreover, spore germination of Aspergillus flavus were inhibited in vitro by the culture filtrate of AN4. Compared to control, only about 30% of spores germination and thinner of hyphae were observed in test. When the culture filtrate of AN4 was applied in the production of fermented soy sauce to control AFB3 contamination, 56.04% of AFB1 biosynthesis was inhibited and 66.93% of AFB3 was degraded, respectively. This research demonstrates that AN4 could effectively control AFB1 contamination and be considered as a promising tool to manage AFB1 in fermented food. [ABSTRACT FROM AUTHOR] |
