Isolation of Lactobacillus bacteria from traditional dairy products in Fars province and evaluation of its probiotic properties

Isolation of Lactobacillus bacteria from traditional dairy products in Fars province and evaluation of its probiotic properties
Neda Zamani,¹ Sorour Aalipanah,^2,* Shohreh nasiri poroj,³
1. Department of Microbiology, Faculty of Life Sciences, Islamic Azad University, North Tehran Branch
2. Department of Microbiology, Faculty of Life Sciences, Islamic Azad University, North Tehran Branch
3. Department of Microbiology, Faculty of Life Sciences, Islamic Azad University, North Tehran Branch
Introduction: Probiotics are a group of beneficial bacteria with special properties that affect the general health of the human body, among other things, they are involved in the improvement of many diseases related to the gastrointestinal tract, such as diarrhea and constipation. Probiotics are used as dietary supplements and they are found in a variety of food products, including dairy products, also with continuous use, they create balance in the intestinal environment. The purpose of this study was to isolate, characterization and identify the probiotic properties of Lactobacillus bacteria, the most important bacteria in this group, from traditional milk and yogurt in Fars province, thereupon a number of isolated bacteria had probiotic properties.
Methods: In this study, different types of local milk and yogurt from different parts of the province were selected. After preparation of dilution and culture in MRS broth and agar, the samples were incubated in CO2 incubator at 37C for 24-72 hours. After that, conventional culture and identification methods were performed on bacteria based on their biochemical properties that including: fermentation of carbohydrates and gas production from glucose, gram staining, catalase test. Then, to investigate the probiotic properties of these bacteria including, pH resistance, high NaCl concentration and bile salts was evaluated. Seven strains of Lactobacillus bacteria were isolated. Also, the antimicrobial effect of these isolates on pathogenic bacteria was evaluated by well method. Therefore, one strain with the best characteristics was selected and other methods such as 16sRNA, PCR and gene sequencing were used for more accurate evaluation.
Results: As a result of these steps, gram-positive isolated lactobacilli were catalase negative, the best growth temperature was at 37 ° C, and were able to use the sugars arabinose, trehalose, xylose, sucrose, fructose, galactose, lactose, mannose, and mannitol, but strains Isolated Lactobacillus.plantarum was negative for inositol and rhamnose. In the case of probiotic tests, it was able to growth at a NaCL concentration of 4.5% and was resistant to bile salts and the optimum pH for growth was 5.5. Also all of them were able to inhibit the growth of pathogenic bacteria. The results of molecular tests showed the isolation of Lactobacillus.plantarum.
Conclusion: The use of probiotic products has a great impact on human health, as a result of this industry is expanding and progressing in the world and the need to study and isolate new bacteria with probiotic properties is very important and a valuable contribution to this industry. The isolated lactobacillus.plantarum has significant probiotic properties that can be valuable for use in dietary supplements.
Keywords: Probiotic, Lactobacillus, Isolation, Dairy products