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Zearalenone (hereafter referred to as ZEA) is a nonsteroidal estrogenic mycotoxin produced by several Fusarium spp. on cereal grains. ZEA is one of the most hazardous natural endocrine disrupting chemicals (EDC) which induces hyper estrogenic responses in mammals. This can result in reproductive disorders in farm animals as well as in humans. Consequently, detoxification strategies for contaminated crops are crucial for food safety. In this study we have developed a bacterial based detoxification system using a non-pathogen Rhodococcus pyridinivorans K408 strain. Following 5 days treatment of ZEA with R. pyridinivorans K408 strain HPLC analyses showed an 87.21% ZEA-degradation efficiency of the bacterial enzyme systems. In another approach, the strain biotransformation ability has also been confirmed by a bioluminescent version of the yeast estrogen screening system (BLYES), which detected an 81.75% of biodegradability of ZEA, in a good agreement with the chemical analyses. Furthermore, the capacity of R. pyridinivorans to eliminate the estrogenic effects of ZEA was tested by using an immature uterotrophic assay. Prepubertal female rats were treated with vehicle (olive oil), 17β-estradiol, ZEA (0.1-1-5-10 mg/kg body weight) and LB broth containing 500 mg/l ZEA that has already been incubated with or without Rhodococcus pyridinivorans K408 strain. Uterine weights were measured and the mRNA level changes relating to apelin, aquaporin 5, complement component 2, and calbindin-3 genes were measured by qRT-PCR. These genes represent the major pathways that are affected by estromimetic compounds. Zearalenone feeding significantly increased the uterus weight in a dose dependent manner and at the same time upregulated complement component 2 and calbindin-3 expression as well as decreased apelin and aquaporin 5 mRNA levels comparable to that seen in 17β-estradiol exposed rats. In contrast, LB broth in which ZEA was incubated with Rhodococcus pyridinivorans K408 prior to the feeding did not display any estrogenic effect neither on uterine weight nor on the expression of estrogen-regulated genes. Consequently, the identification of Rhodococcus pyridinivorans K408 strain in ZEA biodegradation proved to be a very efficient biological tool that is able to eliminate the complete estrogenic effects of ZEA. It is also remarkable that this biotransformation pathway of ZEA did not result in any residual estrogenic effects.

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Ochratoxin-A (OTA) is a mycotoxin with possibly carcinogenic and nephrotoxic effects in humans and animals. OTA is often found as a contaminant in agricultural commodities. The aim of the present work was to evaluate OTA-degrading and detoxifying potential of Cupriavidus basilensis ŐR16 strain. In vivo administration of OTA in CD1 male mice (1 or 10 mg/kg body weight for 72 hours or 0.5 mg/kg body weight for 21 days) resulted in significant elevation of OTA levels in the blood, histopathological alterations- and transcriptional changes in OTA-dependent genes (annexinA2, clusterin, sulphotransferase and gadd45 and gadd153) in the renal cortex. These OTA-induced changes were not seen in animals that have been treated with culture supernatants in which OTA was incubated with Cupriavidus basilensis ŐR16 strain for 5 days. HPLC and ELISA methods identified ochratoxin α as the major metabolite of OTA in Cupriavidus basilensis ŐR16 cultures, which is not toxic in vivo. This study has demonstrated that Cupriavidus basilensis ŐR16 efficiently degrade OTA without producing toxic adventitious metabolites.

a b s t r a c tAflatoxin 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 À1 AFB1 and 1 mg l À1 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.

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Aflatoxin B1 (AFB1) and zearalenone (ZON) are dangerous mycotoxins due to their carcinogenicity or oestrogenicity. To alleviate negative effects on humans and animals, successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins can be an effective way in food and feed industry enhancing food safety. Several Rhodococcus strains are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology. In this study, we investigated the AFB1 and ZON detoxification ability of 42 type strains of Rhodococcus species. Samples were analysed by high-performance liquid chromatograph equipped with fluorescence detector for mycotoxin concentration and SOS-chromotest was used for monitoring remaining genotoxicity. Out of the 42 Rhodococcus strains, 18 could eliminate more than 90% of the applied AFB1 and the genotoxicity was ceased by 15 strains in 72 h (R. imtechensis JCM 13270, R. erythropolis JCM 3201, R. tukisamuensis JCM 11308, R. rhodnii JCM 3203, R. aerolatus JCM 19485, R. enclensis DSM 45688, R. lactis DSM 45625, R. trifolii DSM 45580, R. qingshengii DSM 45222, R. artemisiae DSM 45380, R. baikonurensis DSM 44587, R. globerulus JCM 7472, R. kroppenstedtii JCM 13011, R. pyridinivorans JCM 10940, R. corynebacterioides JCM 3376). In case of ZON, only R. percolatus JCM 10087 was able to degrade more than 90% of the compound and to reduce the oestrogenicity with 70%.