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ABSTRACT: A total of 48 Listeria monocytogenes isolates of different import food products from 8 provinces between 2005 and 2008 were characterized. The serotype and virulence were confirmed for each strain and molecular subtyping were analyzed by multilocus sequence typing (MLST). Twenty five strains were assigned to serotype 1/2a, and 11 isolates to serotype 1/2b, serotype 4b were found in 7 isolate, and the remaining 5 strains were grouped into serotypes 1/2c, 4a, and 4e. Molecular subtyping schemes found thirty two sequence types (STs) among these isolates and the majority of L. monocytogenes strains belonged to lineage II (56%), followed by lineage I (38%), lineage III (6%). Two molecular subtype clusters, cluster A included all isolates of lineage II, while cluster B contained the isolates of lineages I and lineages III. Two L. monocytogenes strains were not grouped in either of the two clusters. Fifty three isolates were as virulent as L. monocytogenes reference strain EGD in mouse virulence assay, while the isolates 22213 and 22265 had low pathogenicity. These results provide the first molecular insight into the L. monocytogenes strains isolated from import food products of 8 provinces in China and indicate the potential risk to cause human disease if intake by contaminated foods. MLST could be used as a routine subtyping method of L. monocytogenes isolates. In China, inspection and quarantine strategies of imported foods should be strengthened. PRACTICAL APPLICATION: There is a potential risk of listeriosis in China and routine subtyping of L. monocytogenes isolates is important. It is necessary for food hygiene management to strengthen the supervision of imported foods.
Journal of Food Science 02/2012; 77(4):M212-6. · 1.66 Impact Factor
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ABSTRACT: To establish a real-time PCR assay for the rapid detection of Listeria monocytogenes in simulated milk specimens.
Based on part fragments of hlyO gene, a pair of primers and Taq-Man probe were designed for quantitative detection of L. monocytogenes. The specificity of the primers and probe were tested by using different L. monocytogenes strains and other common pathogenic bacteria.
L. monocytogenes strains were positive in the detection and other tested strains were negative. The sensitivity of assay was 9 copies per PCR reaction.
The specificity and sensitivity of Taq Man real-time PCR technology for detecting L. monocytogenes in simulated dairy specimens were high, and the assay could be completed within 1.5 h. This method could be used to detect other food samples contaminated by L. monocytogenes and identify the cause of food-borne Listeriosis outbreaks.
Wei sheng yan jiu = Journal of hygiene research 11/2011; 40(6):765-8.
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ABSTRACT: Enterobacter sakazakii, one of the major pathogens affecting the safety of infant formula powder was defined as a species in 1980. However, the new names and new combinations about Enterobacter sakazakii notified in volume 58, part 6, of the International Journal of Systematic and Evolutionary Microbiology (IJSB). The taxonomic relationship of strains described as E. sakazakii, biological characteristics of its new genus and species, the development related to its isolation and identification were reviewed in this paper, in order to facilitate the related personnel to keep in touch with the latest developments on E. sakazakii. It's also conducive to unify and standardize the Chinese name for E. sakazakii.
Wei sheng yan jiu = Journal of hygiene research 03/2010; 39(2):248-50.
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ABSTRACT: A real-time PCR method aimed at the gene sequence of the walnut vicilin-like seed storage protein was established for the detection of the allergen walnut in food. The primers and probe were designed based on published methods. The method provided positive results for walnut and negative results for other tested agricultural plant materials including pecan. The intrinsic detection limit of the method was 0.00125 ng of walnut DNA, and the practical detection limit was 0.001% (wt/wt) walnut content in wheat; both of these values are lower than that of previously published methods. Therefore, this real-time PCR method is sufficiently specific and sensitive for the detection of walnut component in food.
Journal of food protection 11/2009; 72(11):2433-5. · 1.94 Impact Factor
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ABSTRACT: Multiplex PCR–CE–SSCP approach was used to identify foodborne pathogens. 16srRNA system including three target fragments localized
at different position of 16srRNA gene and gyrB system including two target fragments at gyrB gene were established. SSCP profile was analyzed in a similar way as RAPD and the identity of each peak was determined by
relative position to inner standard. Twenty-five reference bacteria strains representing 2 classes, 12 genus and 19 species
were tested. All bacteria could be distinctly determined at genus level by 16srRNA system. GyrB system improved discriminating
resolution of some bacterial at species level. Phylogenetic analysis showed that 16srRNA based phylogenetic relationship was
consistent with traditional classification of these organisms. Good reproducibility and resolution make multiplex PCR–CE–SSCP
protocol a promising approach for fast screening of foodborne pathogens.
European Food Research and Technology 01/2009; 228(4):511-518. · 1.57 Impact Factor
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ABSTRACT: A TaqMan probe real-time PCR method was developed for rapid detection of yak component in raw and cooked meat products. Specific primers and TaqMan probes of yak (Bos grunniens) were designed in the cytochrome b gene. The specificity of the method was evaluated using pure meat of eight yak breeds (Jiulong, Qinghai plateau, Maiwa, Gannan, Bazhou, Sibu, Zhongdian, and Jiali) samples and nine non-Bos grunniens animals (sheep, goat, pig, chicken, cattle, water buffalo, donkey, horse, and rabbit). DNA showed no cross-reaction with non-Bos grunniens animal DNA. This method proved to be sensitive in detecting the presence of low levels of target DNA obtained from 0.001% (w/w) component in a mixed meat sample. The method also successfully identified commercial yak meat products. The results showed that some yak meat might be involved in business fraud by using cattle meat (in this paper, cattle meat means meat of Bos taurus) instead of yak meat. In conclusion, real-time PCR assay used in this study was shown to be a rapid and sensitive method for detection of yak DNA in fresh meat and cooked meat products.
Journal of AOAC International 96(1):142-6. · 1.20 Impact Factor
