The effect of seasonal changes on the physiological and biochemical properties of foodborne pathogenic bacteria isolated from beef carcass-es

In this study, the changes in the physiological and biochemical properties of pathogenic bacteria isolated from samples taken from beef carcass meat depending on the seasons were investigated. The study was continued by detecting bacteria from meat samples using the isolation and identification application method. For this study, raw beef carcass samples obtained from the meat and meat products processing facility in Afyonkarahisar province were evaluated. Raw meat samples were taken from 50 cattle carcasses by determining the dates of 15.01.2023 (winter), 15.04.2023 (spring), 15.07.2023 (summer), 15.10.2023 (autumn) as seasonal. Pathogen isolation studies were started by taking 200 g samples in all seasons and pre-enriching them using %1 (w/v) meet peptone. Different bacteria were isolated in each season. As physiological characteristics of the isolated bacteria; The media in which they showed specific growth were prepared at %2, %5 and %10 salt concentrations, and the bacteria isolated from 4 seasons were cultivated with the help of a sterile loop and incubated for 24-48 hours. After incubation, different growth characteristics of bacteria were observed in different salt concentrations in different seasons. To evaluate the growth characteristics vi of bacteria in acidic and basic environments, specific media were prepared with pH 4 and pH 10. Bacteria isolated in different seasons were planted in these prepared media using sterile loops and incubated for 24-48 hours. After incubation, varying growth characteristics of the bacteria were observed in media at different pH levels. In order to see the development of bacteria with incubation growth temperatures of 30oC and 37oC at different temperatures, the bacteria were planted on specific media with the help of a sterile loop and were incubated for 24-48 hours at temperatures of 4oC, 10oC and 41oC. Fermentative properties of the isolated bacteria were investigated using different types of sugar solutions. Bacteria isolated in %2 (w/v) lactose, fructose, sucrose, sorbitol, dextrose and glucose sugar solutions were incubated at 41oC for 24-48 hours. After incubation, turbidity in the solution due to seasonal changes, gas formation and pH decreases due to fermentation were observed in the sugar solutions of the bacteria. The differences in antibiotic susceptibility of the isolated bacteria depending on seasonal changes were evaluated based on 5 types of antibiotics. For antibiotic sensitivity, bacteria whose density was adjusted to 0,5 in Ringer's solution were planted in 10 μl on Mueller-Hinton Agar medium with the help of a pipette, and Erythromycin, Penicilin G, Clindamycin, Tetracycline and Streptomycin antibiotic disks were placed on them. After 24-48 hours of incubation, the inhibition zone diameters formed by the bacteria around the antibiotic discs were measured and the effects of seasonal change on antibiotic sensitivity were observed. Statistical findings based on the antibiotic sensitivity data obtained confirmed that seasonal change has effects on antibiotic sensitivity. As the biochemical properties of the isolated bacteria; Bacteria that remained actively alive in the media were evaluated by dropping 1 ml of hydrogen peroxide (H2O2) onto the bacteria and the changes that developed in a short time were evaluated as catalase activity. For urease activity, bacteria were incubated in a %2 (w/v) urease solution prepared for 24-48 hours, and turbidity, gas formation and pH changes due to urease activity were examined in the tube. It has been observed that seasonal changes have different effects on the physiological and biochemical properties of isolated bacteria. Based on the results obtained, while the increase in salt concentration inhibited the bacterium, it was determined that C. freundii bacteria did not grow in spring and autumn at 10% salt concentration depending on the season, but showed growth in summer. The vii effect of seasonal differences on the development of bacteria incubated at 4-10-41oC has been determined. L. monocytogenes bacteria incubated at 4oC did not grow in winter and spring, but did grow in summer and autumn. All bacteria incubated at 10oC showed growth. V. cholerae bacteria incubated at 41oC did not grow in summer, but it did grow in winter and spring. The pH of the medium where bacteria generally grow is neutral. In the study, S. flexneri bacteria did not grow in the pH 4 medium in the autumn season, but did grow in the spring season. While S. Enteritidis bacteria did not grow in the pH 10 medium in the autumn season, it did grow in the summer season. A seasonal effect was detected on sugar fermentation of bacteria isolated using different types of sugar. While P. aeruginosa bacteria could not ferment fructose sugar in winter and autumn, it fermented it in spring. While S. Enteritidis bacteria could not ferment sucrose sugar in autumn, it fermented it in summer. While V. cholerae bacteria could not ferment sorbitol sugar in winter and spring, it fermented it in summer. While L. monocytogenes bacteria could not ferment lactose sugar in spring, summer and autumn, it fermented it in winter. It was determined that all bacteria isolated in the study fermented glucose and dextrose sugars. It was observed that the sensitivities of the bacteria isolated in the study using different types of antibiotics changed depending on the seasons. The season when B. cereus bacteria is most sensitive to the antibiotic Erythromycin (E 15) is winter, and the season when it is most resistant is summer. The season when S. Enteritidis bacteria is most sensitive to the antibiotic Penicillin G (P 10) is autumn, and the season when it is most resistant is summer. The season when S. epidermidis bacteria is most sensitive to the antibiotic Clindamycin (DA 2) is autumn, and the season when it is most resistant is summer. The season when E. coli bacteria is most sensitive to Tetracycline (TE 10) antibiotic is summer, and the season when it is most resistant is spring. The season in which P. aeruginosa bacteria is most sensitive to the Streptomycin (S 25) antibiotic is autumn, and the season in which it is most resistant is winter. No effect of seasonal differences was observed on the catalase and urease activity characteristics of the bacteria isolated in the study. Many different microorganisms belonging to the families Pseudomonas, Bacillus, Clostridium, Escherichia, Enterobacter, Enterococcus, Streptococcus, Lactococcus, Lactobacillus, Micrococcus, Listeria, Staphylococcus, Campylobacter, Pediococcus, viii Salmonella, Serratia, Yersinia and Enterobacteriaceae, which can cause spoilage and food poisoning in meat and meat products. There are in order to control microorganisms in meat and meat products, it is necessary to pay attention to personnel and equipment hygiene-sanitization and critical control points during production, starting from the slaughterhouse stage until they reach the consumer. Varying growth characteristics of bacteria were observed depending on different temperatures after incubation.