Screening And Identification Of Zearalenone Degrading Bacteria And The Research Of Related Characteristics

Zearalenone(ZEN)is a secondary metabolite produced by various Fusarium species.It is a highly contaminated mycotoxin.ZEN polluted grains,animal feed and human food,resulting in huge economics losses.It also hazarded animal and human health.The contamination of mycotoxins such as ZEN has attracted great attention.Some physical,chemical and biological means are mainly used to detoxify toxins.The biological detoxification method which is using microbial degradation toxins has the advantage than other methods.And it has gradually become a research focus.The purpose of this study was to screen strains with the ability to degrade ZEN,identify the strains and study the related properties.In this study,the traditional method was used to screen the strains with ZEN as the sole carbon source.A total of 24 degrading bacteria were screened,belonging to 2phyla 13 genera of the bacterial domain.Meanwhile,a screening model based on Biolog microplate technology was established.The strains were screened by using various carbon sources in Biolog Eco plates as screening medium and phenol,a structural analogue of ZEN,as screening pressure.A total of 72 strains of phenol-tolerant bacteria were screened by this method.And 45 strains had degradation of phenol.By further screening,24 strains were with ZEN degradation ability.These 24strains belonged to 3 phyla 7 genera.Among the degraded strains obtained,strain WLB-29 showed the highest degradation ability to ZEN,and the ZEN degradation bacteria WLB-29 was studied.The morphological observation of the strain and the 16S rDNA sequence phylogenetic tree analysis showed that the strain was Stappia genus,and its similarity with the model strain Stappia indica B106~T was 97.47%,which was initially identified as a potential new species.The degradation characteristics of ZEN by strain WLB-29 were also studied.The results showed that the most suitable medium,optimum temperature,optimum pH value,inoculum and ZEN concentration of WLB-29 were LB medium,37°C,8.0,2%and 10?g/mL,and the degradation rate reached 92.56%after 144 h of culture.A strain of high-efficiency phenol-degrading bacteria was also studied.The salt-tolerant strain YZZ-9 showed extremely high degradation ability to phenol.The strain was Kocuria palustris by analysing morphological observation and phylogenic tree of16S rDNA sequences.After testing,the phenol was almost completely degraded by strain at 1.0 g/L phenol concentration for 120 h.When the phenol concentration reached1.25 g/L,the strain still retained 24.4%degradation ability.The degradation rate of ZEN was 68.9%,which proved the feasibility of the screening model based on Biolog technology.The above research results provide a new strain resource for ZEN biodegradation,which has broad application prospects,and also provides a new screening idea for the screening of similar degrading bacteria,which lays a foundation for the establishment of screening models.