Biodegradation of aflatoxin-B1 and zearalenone by Streptomyces sp. collection

Abstract

Aflatoxin B1 (AFB1) and zearalenone (ZON) are hazardous mycotoxins. AFB1 has cytotoxic, mutagenic and carcinogenic effects, whereas ZON can disrupt the endocrine system. Biodegradation by microbes is an effective method to eliminate these hazardous toxins. The aim of this work was to screen AFB1 and ZON biodegrading potential of one hundred and twenty-four Streptomyces strains deposited in the Actinomycetes strain collection of the Department of Environmental Safety and Ecotoxicology. Two different biotests were used for screening purposes: SOS-Chromotest was used to monitor genotoxicity and select microorganisms with the best AFB1 degrading potential. Estrogenic effect of ZON was measured with a yeast based bioluminescent test including human estrogen receptors Bioluminescent Yeast Estrogen System (BLYES). Biodegradation experiments were conducted with 1 mg l−1 AFB1 and 1 mg l−1 ZON concentration. On the base of the results, ten strains were selected for biodegradation experiments and Enzyme-linked Immunosorbent Assay tests (ELISA). The results of these tests Streptomyces cacaoi subsp. asoensis (K234) strain degraded AFB1 over 88 per cent and totally eliminated genotoxicity. Two strains of Streptomyces rimosus (K145, K189) degraded almost total amount of ZON and estrogenicity was not detected besides that.