Isolation and characterization of novel soil bacterium, Klebsiella pneumoniae strain GS7-1 for the degradation of zearalenone in major cereals

Zearalenone (ZEN) is one of the major agricultural feed contaminants causing serious health hazards worldwide and its degradation by beneficial microbial agents is now being widely examined. In this study we investigated the degradation ability of Klebsiella pneumoniae strain GS7-1 isolated from corn field in Shandong province in China on ZEN. The effects of temperature, incubation time and pH were studied. Furthermore, it was examined if the washed cell pellet and the supernatant of fermented culture (SFC) of the bacterial cell components could detoxify ZEN. ZEN removal increased with increase in pH from 61.3% at pH 5–100% at pH 8. The minimum and maximum temperatures at which K. pneumoniae strain GS7-1 degraded ZEN were 28 °C and 60 °C, respectively. Increase in incubation time increased the degradation effect as ZEN was completely degraded at 96 h. The SFC of strain GS7-1 reduced the ZEN content by 100%, while the first and second washed of the cell pellets in PBS reduced the ZEN content by 30% and 25%, respectively. The rate of SFC degradation significantly decreased after treatment with proteinase K, SDS and the combination of proteinase K and SDS. There exists a significant correlation between temperature, incubation time and pH regarding ZEN degradation by strain GS7-1. The results also suggest that enzymes present in the supernatant of Klebsiella pneumoniae GS7-1 were involved in ZEN degradation. The biodegradation of ZEN is a very feasible method for food and feed purification as physical and chemical methods may not only eliminate mycotoxins, but also nutrients and sensory-related compounds.