Study On Isolation And Identification Of ZEN-degrading Bacteria From Rumen And Its Degrading Characterizatics

Zearalenone (ZEN) is a nonsteroidal oestrogenic mycotoxin which causes hyperestrogenism and related toxicosis of farm animals and humans. ZEN spread widely in crops and by-products all over the world, not only damage human and animal’s health, and bring a huge economic losses on livestock breeding. Currently, various physical, chemical and biological methods have been developed to decrease the ZEN, biological methods have been the most popular topics for research because of its safety and efficiency, especially biodegradation.Ruminants are known to be very resistant against toxic effects of mycotoxins while rumen fluid has rich microbial resources.The present study aims to isolate and identify efficient ZEN-degrading bacteria from rumen. With the analysis of colony morphology, biological characteristics and 16S rRNA gene sequence to identify the strain; studying the effects of different conditions on ZEN-degrading, degradation characteristics. The particular information of this study was described as follows:(1)One bacterium capable of efficient degrading ZEN was successfully isolated from rumen contents which ZEN was as a sole carbon source, named TH-N1.The degradation rate of ZEN (2μg/mL) reached 59% under 37℃,pH 6.5,160 r/min after 72h;(2)The strain was belonging to Pseudomonas based on colony morphology, biological characteristics and 16S rRNA gene sequence, which named as Pseudomonas otitidis TH-N1;(3)To study the effects of different conditions on ZEN-degrading, several factors such as incubation time, culture temperature, initial pH and initial bacterial concentrations were investigated, the optimum results were:37℃, pH 4.5 and the cell concentration was 109cfu/ml for 72 h in MS medium;(4)The ability of heat-inactivated cell, cell-free supernatant, intracellular cell extract and cell wall to degrade ZEN was also investigated, the degradation rate of the activated cell and intracellular cell extract for ZEN (2 μg/ml) were 59% and 38%, respectively, had a more strong ability to degrade ZEN than while the heat-inactivated cell, cell-free supernatantand、cell wall、cell-free supernatant could rarely degrade ZEN, indicating that intracellular enzyme of strainTH-Nl may working in degrade ZEN.