Establishment Of A Method For Detection Of Salmonella And Streptococcus Thermophilus In Food

There are many kinds of bacteria that survive in food,and the depth of their research varies.To establish a method for detecting certain bacteria,different methods can be adopted depending on the degree of research.For the more thorough research strains,the genetic structure is very clear.Generally,literature search and gene analysis are used to determine the detection target and establish the detection method.However,for those strains with few studies,if the gene sequence is not clear,The target method is screened by the test method,and then the detection method is established.In order to carry out more effective detection of various bacteria in food,this experiment starts with two bacteria that are very common in food: the Salmonella typhimurium is established by using the foodborne pathogen Salmonella,which causes very high food poisoning rate.Detection method;the fermenting strain S.thermophilus commonly found in fermented dairy products is studied,and a high sensitivity detection method for s RNA is established.Through the research on Salmonella and Streptococcus thermophilus,new methods and research ideas will be provided for the detection of these two bacteria,which have important reference significance for the establishment of bacterial detection methods in food.Various rapid detection methods for bacteria in food have great application prospects in the on-site detection of food.The main research contents and methods are as follows:1.To establish a rapid method for detection of Salmonella by RPA,we worked as follows.The first was designing the primers and probes.We selected the conserved region KJ883520 in Salmonella genome as the detection target by consulting relevant data and comparing genomic sequences.By this way,eight primers and one probe were designed and synthesized.The second was establishing the detection method.Sixteen pairs of primer combinations consisting of eight forward and reverse primers were screened to find one pair of primer combinations with the highest amplification efficiency.At last,the specificity and sensitivity of the method were evaluated.The results showed that the method had good specificity.The minimum detection limit for Salmonella was 10 copies.Rapid detection of Salmonella spp.by RPA provides a more rapid and convenient method for identification of food-borne pathogens.2.Streptococcus thermophiles was used as the research object to establish a highly sensitive detection method for s RNA.The first is to predict the existence of s RNA.We used the Illumina Hi Seq2000 platform to sequence the whole genome of Streptococcus thermophiles,compared in the database,and analyzed the gene function of the genome.Through the prediction of non-coding RNA,we predicted 15 s RNA.The second is to amplify the DNA fragments and RNA fragments at the same time by taking these s RNA as detection targets,and then to compare the differences of their sensitivity of DNA and RNA.In this way we screened two high transcripts of s RNA to establish the detection method.The detection of Streptococcus thermophiles with s RNA as the target provides a new idea and direction for the study of bacterial detection in food.In summary,this test successfully established a rapid detection method for Salmonella and a high sensitivity detection method for Streptococcus thermophilus.