| Aflatoxin(AFT)is a secondary metabolite produced by Aspergillus flavus,Aspergillus parasiticus,Aspergillus nomius and other fungi of Aspergillus,and the fungaltoxin most harmful to human health and social economic development.The method of AFT biodegradation has a series of advantages such as high efficiency,safety and environmental friendliness.It has become the hot spot focused by researchers in recent years.In order to explore the biological detoxification agent of AFT that can be used in actual production,a strain of Myroides odoratimimus 3J2MO was selected in this study to study its ability to degrade AFT:1.The study showed the ability of Myroides odoratimimus 3J2MO to degrade various AFTs.The bacterial strain 3J2MO was mixed and cultivated with different concentrations of AFTs and their precursor sterigmatocystin for 5 days,and the toxin degradation rate was determined and calculated.Results show that under processing of bacterial strain 3J2MO,AFTs(AFB1、AFB2、AFG1、AFG2、AFM1)and sterigmatocystin were degraded.Among them,aflatoxins can be degraded more than 500 ng per milliliter of bacterial solution The results of research and literature comparison show that Myroides odoratimimus 3J2MO is the bacterial strain which can efficiently degrade most kinds of AFTs,which provides a new material for the pollution reduction and control of AFT in agricultural products.2.The study clarified the safety of Myroides odoratimimus 3J2MO and fermentation broth of its degradation AFB1 product.By the pathogenicity test of acute intraperitoneal injection in mice,the pathogenicity of bacterial strain 3J2MO and fermentation broth of its degradation AFB1 product was determined,and the results showed that the two had no pathogenicity;the acute transoral toxicity of the two was determined by the acute transoral toxicity test in rats,and the results showed that the acute transoral toxicity of the two was low toxicity level;and the acute percutaneous toxicity of bacterial strain 3J2MO and fermentation broth of its degradation AFB1 product was determined by the acute percutaneous toxicity test in rats,and the results showed that the acute percutaneous toxicity level of the two was low toxicity level.Results of the study show that degradation of AFTs in agricultural products by Myroides odoratimimus 3J2MO has the characteristics of high efficiency and safety and the important development value.3.The safe degradation technology of AFT by Myroides odoratimimus 3J2MO in peanut meal through solid state fermentation was established in the study.Through single-factor study,it was proved that culture time of bacterial solution,culture time of sample and inoculation amount of bacterial solution were the main influencing factors for bacterial strain 3J2MO to degrade AFT in peanut meal.Through the test study on response surface,the optimal process conditions for the safe degradation technology of AFT by Myroides odoratimimus 3J2MO in peanut meal were finally determined.That is,the culture time of bacterial solution was 29.04 h,the culture time of sample was 78.72 h,and the inoculation amount of bacterial solution was 4.12 mL(the bacterial concentration was 2.39*10~9 cfu/mL).The degradation rate of AFT in peanut meal was up to 71.95%by using the established safe degradation technology of AFT by Myroides odoratimimus 3J2MO.This study provides an efficient and safe new method for the pollution reduction and control of AFT in agricultural products.4.The whole genome sequence of Myroides odoratimimus 3J2MO was determined and candidate degrading enzymes were searched for.The whole genome sequencing and assembly was completed for bacterial strain 3I2MO.The sequencing results show that the genome of the bacterial strain is composed of a cyclic chromosome,there is no plasmid,and the genome size is about 3.99 Mbp.Functional genes were marked and analyzed.A possible AFT degradation enzyme was preliminarily positioned,which provided scientific basis for the revealing of mechanism of degradation.The results of this study indicated that Myroides odoratimimus 3J2MO provided a new way to develop AFT detoxification agent for agricultural products. |
