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Objective To develop a rapid and sensitive DNA microarray for Listeria monocytogenes detection.Methods A DNA microarray was developed using gyrB,ISR,16S rRNA,23S rRNA,hlyA,iap and prfA as the target genes and tested against 18 different species of known reference for repeatability,sensitivity,and specificity to verify the effectiveness of the chip.Results After testing of samples by the LM array,results show that the 70 mer Oligos synthesized by IDT are superior to the Oligos synthesized by Sagon with respect to both probe spotting or samples detection.The comparison of 3 spotting probe concentrations of 10 μmol/L,40 μmol/L and 80 μmol/L demonstrated that the 10 pmol/L probes result in good detection signals equivalent to the 40 μmol/L and 80 μmol/L probes.The repeatability and sensitivity evaluated by sample testing on the LM array revealed that the chips developed in this study have good repeatability and the lower limit of sample detection is 0.9 ng DNA.The LM array can distinguish clearly and definitively between Listeria and non-Listeria bacteria in the sample.Conclusion The microarray is able to rapidly detect and identify Listeria monocytogenes.
RESUMO
Objective To understand the microbiological pollution of drinking water dispensers and find out the effective disinfection method for dispensers. Methods The counts of bacteria, fungi and yeast in water samples collected from the water stored in liners of 52 drinking water dispensers were determined. The total counts of bacteria in water samples of 8 water dispensers were determined before and after disinfection by 1/10 YOUJIE disinfectant for 2 min. Results The medians and over standard rates were 440 cfu/ml and 96.15% for the total count of bacteria, 0 and 30.77% for fungi and yeast in the water samples before disinfection respectively. After 2_min disinfection by 1/10 YOUJIE disinfectant, 5 of 8 drinking water dispensers showed bactericidal rates of 100% and other 3 water dispensers showed bactericidal rates of 99.56%, 99.77% and 99.78% respectively. Bacillus was found in some unkilled bacteria. Conclusion Microbiological pollution in water stored in liners of drinking water dispensers was high, which could be effectively eliminated and disinfected by 1/10 YOUJIE disinfectant for 2 min.