Research Of Rapid Detection Technologies For Escherichia Coli And Coliforms In Aquatic Products

Escherichia coli and coliforms are used as important indicators for determining faecescontamination in water， drug and food. Conventional technologies of E. coli and coliformsdetection have some disadvantages such as long time consuming， low sensitivity， poorspecificity， and unable to detect the slow growing or viable but not cultivable(VBNC)microbe.Three rapid detection technologies based on the molecular biology technology，immunological technology and enzymatic technology have been developed. The rapid detectiontechnologies have advantages of high sensitivity，good specificity，and rapid detection. Amongthem， the enzymatic technology is fit for rapid quantitative detection of E. coli and coliforms inaquatic product because of the several advantages such as less time-consuming and moreeconomical compared with molecular biology technology and immunological technology. Theprogress of development of the three detection technologies is reviewed in this paper， and theexpectation of application in aquatic product is also probed into. Single tube quantitativedetection technology for E.coil assay based on fluorescent method had been established by ourlaboratory. For a better investigating of the application area of single tube quantitative assaytechnology so that the product can be rapidly detected before marketing.In this paper， singletube quantitative detection technology for detecting coliforms was established.And comparisonbetween single tube quantitative assay technology and traditional method was conducted byintroduction these two method in E. coli and coliforms assay for bacterial suspensions preparedby the laboratory， natural seawater， and fishery product samples.Then，the future applicationof single tube quantitative assay technology was evaluated.As follow for concrete research：Influence of incubation temperatures and pH values of culture liquid on growth of coliformsand the OD values of culture liquid had been investigated.Coliforms incubated at42℃in theculture liquid with a pH value in the range of7.0～7.5was found to be the best condition ofdetection for OD values of ONPG enzymolysis product.Single tube quantitative detectiontechnology to detect coliforms was established through the studies on the relationship betweenincubation time， inoculation quantity of coliforms and the OD valuess of cultureliquid．Relatively standard diversity of single tube detection technology was lower than those ofcolony-counting method and the most probably number method．The results indicated that thesingle tube quantitative detection method was fit for coliforms quantitative detection because ofthe several advantages such as less time-consuming and more economical compared with traditional methods.Comparison between MUG single tube quantitative assay method and E. coli multiple tubefermentation technique was conducted by introduction these two method in E. coli assay forbacterial suspensions prepared by the laboratory， natural seawater， and fishery productsamples.The results showed that： no significant difference was found between the results ofsingle tube quantitative assay method and multiple tube fermentation technique; single tubequantitative assay method showed better accurateness， precision， and reproducibility thanmultiple tube fermentation technique; single tube quantitative assay method was more quicklyand economy. The results indicated that MUG single tube quantitative assay method was suitablefor the E. coli enumeration in seawater and fishery products.Comparison between ONPG single tube quantitative assay method and lactose multiple tubefermentation technique was conducted by introduction these two method in coliforms assay forbacterial suspensions prepared by the laboratory， natural seawater， and fishery productsamples. The results showed that： no significant difference was found between the results ofONPG single tube quantitative assay method and lactose multiple tube fermentation technique;ONPG single tube quantitative assay method showed better accurateness， precision， andreproducibility than lactose multiple tube fermentation technique; ONPG single tube quantitativeassay method was suitable for the rapid evaluation of coliforms from water samples. Furtherstudies are require to decide whether the ONPG single tube quantitative assay method is suitablefor the coliforms evaluation of aquatic product.In conlusion， MUG single tube quantitative assay technology was suitable for the E. colienumeration in seawater and fishery products; ONPG single tube quantitative assay technologywas suitable for the rapid evaluation of coliforms from seawater samples. Further studies arerequire to decide whether the ONPG single tube quantitative assay technology is suitable for thecoliforms evaluation of aquatic product.And then， quantitative assay for simples come fromdifferent site and time is still investigated to enlarge quantitative assay of single tube quantitativeassay method.