Huang Kunlun

Ochratoxin A and ochratoxin-producing fungi on cereal grain in China: a review

The mycotoxin ochratoxin A (OTA) is known to be the main contaminant of cereal grain and has become increasingly important in recent years. Therefore, a survey of ochratoxigenic fungi and OTA contamination in China is a special challenge. This paper summarises data on cereals and moulds (Aspergillus niger, Penicillium verrucosum, Aspergillus ochraceus, for example) and on grain and OTA from 1973 by searching Chinese information databases (NCKI, VIP, DuXiu etc.), calculating the OTA-producing mould detection rate, referring to sampling locations, latitude and temperature, and also combining six grain-producing areas of ochratoxigenic fungi and OTA positive rate through a comprehensive analysis. It is concluded that in China rice (excluding shell rice) has less OTA contamination than wheat or maize. The contamination of cereal grains with Aspergillus section Nigri (formerly of the A. niger group) is a serious problem in China, and these fungi may be the main ochratoxigenic fungi on cereals.

Real-time quantitative PCR detection of Escherichia coli O157:H7

A rapid and accurate real-time quantitative polymerase chain reaction (Real-time PCR) method with SYBR GreenⅠfor detecting Escherichia coli O157:H7 was established. A pair of amplify primers were designed to amplify eae gene. The dissociation curves showed that the amplified product was very specific. The optimal reaction program and standard curve were founded. The result indicated that Real-time PCR was sensitive 1000 times more than ordinarily PCR.

Enzyme linked immunosorbent assay for PAT protein detection in genetically modified rape

The immunoassay method to detect genetically modified (GM) rape(Brassica campestris ) containing the phosphinothricin acetyltransferase (PAT) were developed and applied. The purified PAT was identified by Western blot and enzymic activity analysis. The polyclonal antibody against purified PAT protein was obtained and purified by both saturated ammonium sulfate method and protein A-Sepharose 4B. The sensitivity and cross-reactivity of polyclonal antibody has been demonstrated in ELISA test. The result of the ELISA for antiserum sensitivity was about 2×10-5 mg/mL and the cross-reactivity determined experimentally showed a high degree of specificity for the antiserum used, because values were all less than 0.1 %. The detections of transgenic plants were evaluated with two transgenic rapes (MS1/RF1 and MS8/RF3) and the transgenic rapes (MS1/RF1 and MS8/RF3) could be easily distinguished by ELISA.

PCR for the detection of the anti-herbicide genes in genetically modified organisms

Genetically modified organisms (GMOs) containing anti-herbicide genes account for more than 75% of all GMO and the proportion is increasing. The polymerase chain reaction (PCR) method has proved to be an invaluable tool for the specific and sensitive detection of genetically modified material in foodstuffs and PCR screening for the presence of transgenic components in food is becoming a routine method in modern food analysis. In this study, the five kinds of the anti-herbicide genes (bar, pat, cp4-epsps1, cp4epsps2 and gox) were examined by PCR in four kinds of genetically modified crops (soy, maize, cotton and rape). Results indicate that the method was sensitive, specific and credible, and that all genetically modified and approved crops containing the anti-herbicide genes can be examined by this method.