Distribution Characteristic Of Cronobacter In Cereals And Related Environment

Cronobacter is a serious health hazard to human,the main people infected with Cronobacter are the infants and the old people with low resistance,it has attracted the attention of relevant scholars at home and abroad for its high mortality and wide distribution.In this study,Cronobacter was used as the research object to analyze the distribution characteristics of the growth cycle,growth environment,processing places and family samples of the cereal grains and products,wheat and rice by means of smear and other sampling methods,such as detection,quantification and molecular typing.With a view to provide a theoretical basis for the prevention and control measures of Cronobacter.In view of the above research,the following conclusions are drawn:(1)The positive detection rate of Cronobacter was 12%in the cereal samples.The positive detection rate of Cronobacter in cereal products was 40.4%;The positive detection rate of Cronobacter of wheat related products and rice was 46.9%and 39.1%respectively.The positive detection rate of Cronobacter in flour was 100%;The lowest detection rate of Cronobacter in wheat and rice instant products,the surface through heating and other processing can reduce the distribution of the bacillus Cronobacter in grain samples.(2)Quantitative analysis results showed that the concentration of Cronobacter in cereal samples was 0.36 MPN/100g-110 MPN/100g,the average concentration was 12.85 MPN/100g,the median concentration was 14.3 MPN/100g.The analysis showed that the concentration of Enterobacter sakazakii in 76.9%sample was less than 10 MPN/100g(average 2.92 MPN/100g),and the concentration of Cronobacter in 2 samples was>100MPN/100g.The infection quantity of Cronobacter was generally lower in the sample,and the average bacterial dye concentration was high,the positive detection rate of Cronobacter was higher.Different cereal foods and products of Cronobacter positive detection rate differences,including flour might be a kind of Cronobacter natural storage place,in the process of the spread of e.sakazakii play an important role.(3)The biochemical detection of Cronobacter showed that:Cronobacter was the most sensitive to β-n-acetyl-glucosamine(βNAG),lysine decarboxylase(LDC),inositol(INO),malonic acid(MNT)and old sugar(PLE),so the five kinds of saccharides could be used as important indexes to distinguish Cronobacter with other bacterium.(4)Cronobacter had been detected from both the wheat and rice in different growth cycle.The positive detection rate of Cronobacter in different wheat growth cycle was 3.0%to 16.9%while the rice is 7.3%to 26.0%.And 6.3%in paddy field water samples.But,it was not detected in rice and wheat soil samples.The positive rate of Cronobacter in rice samples in different growth period was higher than that in the same period of wheat samples.(5)Place of flour and rice processing(sampling from Huaibei in Anhui,Luohe in Henan and Zhuji in Zhejiang,Huangshan in Anhui)Cronobacter detection rate were 62.12%and 51.52%respectively,Cronobacter positive rate is extremely high,which is in the flour and rice flour Cronobacter positive rate high reason,may be due to the production process and environment factors of cross contamination.(6)Through the detection of Cronobacter in the family environment of different communities in Hangzhou,we found that 7 samples of 12 families in Xiaoshan district detected Cronobacter,the highest positive rate was 58.33%.But only 1 positive samples were detected in 9 families of the Lower urban area,the lowest rate was 11.11%.Only 7 of the 52 family samples in jianggan district were positive,the positive rate was 13.46%.For the while,7 of the 30 family samples in the West-lake district showed positive,the positive rate was 23.33%.(7)The total detection rate of 103 family samples was 21.36%.The detection rate of Cronobacter in the ground,basin,hearth,vacuum cleaners and toaster in household samples was higher,accounting for 11.63%,18.6%,16.28%,16.28%,13.95%,respectively.At the same time,the detection rate of Cronobacter in the household environment of southern households was 0,and the detection rate was 66.67%in northern families.That is,dietary habits have a greater effect on the distribution of Cronobacter in the family,and the bacillus Cronobacter is more widely distributed in families that prefer to eat pasta.(8)The molecular typing showed that the samples showed different genotype diversity in each stage,further analysis showed that the similarity coefficient of Cronobacter samples separated from the same location was higher,that is,the relationship was closer,and the high diversity of PFGE type to a certain extent,the common presence of Enterobacter sakazakii in the samples,at the same time,the samples also had a high similarity coefficient.