Prevalence of virulence factors and antibiotic resistance in lactic acid bacteria isolated from traditional dairy products
Prevalence of virulence factors and antibiotic resistance in lactic acid bacteria isolated from traditional dairy products
Armin Moghadam,1Mohammad Javad Rezaei,2Ehsan Sohrabi ,3Seyed Saeed Mirdamadi,4Mohammad Mohammadi,5Ali Naghoni,6,*
1. Research and Development Unit, Fara Daru Fanavar Mehr Pharmaceutical Co., Tehran, Iran 2. Research and Development Unit, Fara Daru Fanavar Mehr Pharmaceutical Co., Tehran, Iran 3. Research and Development Unit, Fara Daru Fanavar Mehr Pharmaceutical Co., Tehran, Iran 4. Iranian Research Organization for Science and Technology (IROST), Tehran, Iran 5. Fara Daru Fanavar Mehr Pharmaceutical Co., Tehran, Iran 6. Research and Development Unit, Fara Daru Fanavar Mehr Pharmaceutical Co., Tehran, Iran
Introduction: Lactic acid-producing bacteria are the most commonly used probiotics in foods and dietary supplements. It is well known that probiotics have a number of beneficial health effects in humans and animals. Probiotics are distinguished by astonishing criteria: improving the balance of the microbiota inside the intestine, inhibiting pathogenic microorganisms in the gastrointestinal tract, adjusting the intestinal environment, ability to reduce pathogen adhesion activity, capabilities of regulating intestinal mucosal immunity, and maintaining intestinal barrier function. Since these bacteria are typically viable when consumed, considerable characterization is required to ensure the absence of undesirable properties.
Methods: In this study, 244 strains from different sources of traditional dairy products such as, yogurt, yogurt drink, milk, and butter were collected from different regions of Iran. 18 out of 240 LAB isolates were selected due to their primary probiotic properties (resistance to low pH, bile tolerance, and tolerance to pepsin and trypsin) and identified by phenotypic and 16S rRNA gene sequence analysis. The 20 isolated species were assessed for the incidence of virulence genes (gelE, efaAfm, efaAfs, ace, espfs, cylM, cylA and cylB), sensitivity to different antibiotics. The incidence of virulence genes was determined by polymerase chain reaction and antibiotic susceptibility was assessed by disk diffusion method.
Results: The dominant bacterial genera isolated were Lactobacillus, Lacticaseibacillus, and Bifidobacterium. Also, the results of this study showed no virulence genes for all 20 isolated species. In addition, minority of strains showed only low level of resistance to rifampicin and chloramphenicol and were sensitive to all other antibiotics tested for.
Conclusion: The results of this study showed that our isolates can be good candidates for using as a probiotic. However, for further assessment, it is recommended that whole-genome sequencing of each strain be performed.