جستجوی مقالات مرتبط با کلیدواژه "real time pcr" در نشریات گروه "صنایع غذایی"

Corn and soybeans have the largest area of ​​GM crops in the world. Milk powder and baby food are processed foods that contain corn and soybeans. Therefore, tracking transgenic corn and soy in processed food is one of the research problems. First, 40 samples of baby food and milk powder were collected from pharmacies and supermarkets in Tehran. All the samples were extracted using Azmaelixir DNA kit, and the nucleic acid concentration was checked with a nanodrop device, and internal control genes for soy (Lectin) and corn (Zein) were checked to ensure the extraction. Then, the presence of CaMV35S transgenic gene was checked by Real-time PCR technique. The results showed the presence of transgenic genes in 2.5% of baby food samples and 10% of samples in infant formula. Therefore, in this article, the amount of transgenic gene penetration in baby food and infant formula has been investigated.

Poultry and meat products are the largest sources of non-typhoid salmonella infections in most countries. Studies have shown that raw foods of animal origin, especially poultry and its products, are the main source of contamination of kitchens and restaurants. In terms of growth conditions, these microorganisms are resilient bacteria and easily adapt to their environmental conditions. Salmonella has been known to cause intestinal disease for many years and has been reported as the most important cause of food poisoning. According to Iranian and international standards, there should be no S. enteritidis or S. typhimurium in 25 grams of food. DNA-based methods for the identification and differentiation of Salmonella serovars have been designed and applied using specific primers at the genus and serovar levels. Therefore, they can be used as useful and rapid screening tests, as well as to supplement or replace conventional biochemical and serological tests. Real-time PCR, with the most accurate and reliable results using a fluorescence probe, which of course has a high cost. In this method, sequence specific fluorescence probes are used, and as a result, in the target molecule, screening and determination the presence or even the concentration of specific sequences is possible. Therefore, even in the presence of other types of nucleic acid molecules, the results are obtained quickly and have a high level of specificity. Under these conditions, if specific probes with different florescence dyes are used, even multiple targets can be detected in a single PCR reaction. The aim of this study was to identify S. enteritidis or S. typhimurium by PCR and Salmonella spp. by real time PCR method in poultry products. 

In total, 45 samples of poultry products, including chicken breast, liver and gizzard (15 samples each) were purchased from different regions of Mashhad and from various companies and transferred to the laboratory in accordance with hygienic standards. For each sample, 25 g of tissue was isolated and homogenized under sterile conditions and DNA extraction was then performed using a DNA extraction kit. The extracted DNA was evaluated by agarose gel electrophoresis. The purity and quantity of DNA extracted from each sample was examined by spectrophotometry method. In the next step, in order to identify the genus Salmonella, the samples were examined by real time PCR. In this method we used an internal control to ensure that negative results are not false negative due to inhibitors. The results of real time PCR showed that out of 45 samples, nine samples were infected with Salmonella. Then, these nine samples were evaluated for Salmonella typhimurium and Salmonella enteritidis infection by conventional PCR method. 

The results showed that out of nine samples that were positive in real time PCR test, seven samples were contaminated with Salmonella typhimurium, of which five samples were related to chicken breast and two to liver. Regarding Salmonella enteritidis infection, out of nine samples, only one sample was contaminated, which was related to chicken breast. Conventional methods have been traditionally used to enumerate target bacteria in food. However, these methods have some limitations and require considerable time and labor. Previous studies have already shown that real time PCR is more effective than conventional bacteriological methods for the detection of Salmonella spp. In a study by Whyte et al. (2002) The presence of Salmonella was assessed by traditional culture methods and by a Salmonella-specific polymerase chain reaction (PCR) test. Salmonella was recovered from 16% of samples using traditional culture methods. In contrast, the PCR assay proved to be more sensitive and detected Salmonella DNA in 19% of the examined samples (Whyte et al. 2002). Results of PCR with specific primers showed that reactions in real time PCR with general primers of Salmonella spp. were done correctly. Despite of accuracy and speed of real time PCR to detect DNA of microorganisms, further studies are developed to have more advantages. Loop-mediated isothermal amplification (LAMP) showed a higher sensitivity of Salmonella detection in compare to qPCR (Vichaibun & Kanchanaphum, 2020). Although LAMP could detect trace amount of Salmonella DNA but primer design for this reaction is very difficult. However, it is important to highlight that non-viable cells can be detected by real time PCR or other DNA-based methods, which does not occur in traditional methods of culture and isolation that require viable cells for quantification (Zeng et al., 2016).

Nowadays, the need for new strategies to control the activities of resistant bacteria is felt more than ever. In this regard, a very promising approach is the use of nanomaterials science and the knowledge that is expanding in the field of Nano synthesis biosynthesis should be considered as a global strategy. The aim of this study was to evaluate the antibacterial properties of biosynthetic copper oxide nanoparticles on the expression of the AmpC gene in Pseudomonas aeruginosa. 10 samples of P. aeruginosa were collected from clinical centers of Khorramabad city in 1399 and identified based on biochemical tests. After treatment of MDR strains with the minimum inhibitory concentration of copper oxide nanoparticles, the expression level of the AmpC gene was evaluated using real-time PCR. After applying the effect of biosynthetic copper oxide nanoparticles on AmpC gene expression and calculations performed by MIC and ANOVA one-Tukey statistical analysis test, it was found that copper oxide nanoparticles have an inhibitory effect on the expression of AmpC genes of P. aeruginosa samples. The objectives of this study focused on the use of nanotechnology as a new tool to address current challenges in the treatment of infectious diseases and antibiotic resistance. Therefore, for safer use of this nascent technology, the need for clinical trials and further research at the level of molecular biology is recommended.

Detection of the residual meat or other components of pork in halal food products particularly in Muslim countries is of prime importance. In this study, real-time polymerase chain reaction based on SyberGreen dye was used for detection of pork DNA in meats and highly processed products such as pork gelatin and gelatin-containing products. SyberGreen based real-time polymerase chain reaction was designed for an assay that can detect pork DNA in meats and highly processed pork derivatives including gelatin and gelatin containing products. The proposed method uses the newly specific primers designed by AlleleID7 software that amplify a 114 bp fragment of porcine mitochondrial D-loop region. After optimization of mixture composition and thermal program for achieving maximum fluorescence and minimum threshold cycle, standard curve of serially diluted DNA extracted from pork meat showed power for detection of 0.001 diluted DNA compared with starting DNA material with the efficiency of 92%. Specificity of this method was evaluated by testing the extracted DNA from sheep, cow, chicken and fish which had no amplification for negative control samples. To analyze the method for detecting highly processed pork derivatives, several pork gelatin powders and sheets were selected and the real-time polymerase chain reaction based on SyberGreen dye proved to successfully detect the traces of the pork residues in the samples tested.