Abstract:
【Objective】 In order to solve the problem of aflatoxin B
1(AFB
1)contamination in feed and food, an AFB
1- degrading strain was screened from soil samples and its capacities for degradation of AFB
1 and inhibition of Aspergillus flavus growth were studied.【Method】 Using coumarin as the sole carbon source, an efficient AFB
1 degrading strain was selected. The species of the strain were identified by 16S rRNA gene sequencing and its degradation characteristics of AFB
1 were studied by High performance liquid chromatography(HPLC). The degradation efficiency of GDAAS003 on AFB
1 was optimized by single factor experiment, and the inhibition effect of GDAAS003 on
A. flavus growth was analyzed by co-culture. Finally, the SOS-Chromotest was used to evaluate the detoxification of AFB
1 by the strain.【Result】Through HPLC detection, a highly efficient AFB
1-degrading strain was selected. 16S rRNA analysis showed that the sequence of GDAAS003 was 100% homologous to that of
Streptomyces cerasinus SR3-134(LC128347.1), and that the AFB
1 degradation activity was extracellular and enzymatic. The results showed that the optimum pH of supernatants to degrade AFB
1 was 8.0 in Na
2HPO
4/NaH
2PO
4 buffer and that the optimum temperature was 30℃. Under the optimized condition, the degradation rate of 50 and 100 ng/mL AFB
1 in 96 h of strain supernatant was 90.50% and 75.68%, respectively. Moreover, the genotoxicity test results of the degradation products showed that the degradation products did not show genotoxicity. In addition, GDAAS003 could inhibit AFB
1 synthesis by
A. flavus in maize.【Conclusion】Streptomyces GDAAS003 not only degraded AFB
1 with high efficiency, but also inhibited the growth of
A. flavus. It has a great application prospect in the food and feed industries.