Evaluation of antimicrobial effect of probiotics isolated from Gilan province traditional milks against Candida albicans as well as Pseudomonas aeruginosa and comparision with standard probiotics strains.
Evaluation of antimicrobial effect of probiotics isolated from Gilan province traditional milks against Candida albicans as well as Pseudomonas aeruginosa and comparision with standard probiotics strains.
Moayed Atashak,1,*Mahnaz Farahmand,2Elaheh Ali Asgari,3
1. Department of biology, Basic Science Faculty, East Tehran Branch, Islamic Azad University, Tehran, IRAN. 2. Department of biology, Basic Science Faculty, East Tehran Branch, Islamic Azad University, Tehran, IRAN. 3. Department of biology, Basic Science Faculty, East Tehran Branch, Islamic Azad University, Tehran, IRAN.
Introduction: Probiotics are alive microorganisms which are added to human and animal diet for improving and correcting bacterial flora; probiotics are able to restrain unwanted colonization of pathogens in the digestive system. Additionally, probiotics are capable of eliminating pathogens through secreting various bacteriocin materials such as Acetate, Propionate, and Hydrogen peroxide. Candida albicans is a species of yeast which lives in symbiotic relationship with the skin, oral, gut, and vagina of its host. In normal conditions, C.albicans do not cause harms to their host, but the tension of the immune system creates the opportunity for it to manifest itself as a pathogen. Pseudomonas aeruginosa is a similar opportunist microorganism that in case of immune system weakness results in several types of infections including - but not limited to - urinary track, respiratory system, and gastrointestinal infections, particularly in patients suffering from cancer or HIV. Therefore, due to the range of diseases that these pathogens have caused for human beings, and arbitrary consumption of antibiotics that has increased their resistance to old-fashioned medications, finding new ways which are safe, permanent, and available seems necessary. Considering the variety of detriments caused by the aforementioned pathogens and the medical benefits of probiotics, we aimed to identify probiotics from local milk for potential use against C.albicans and P.aeruginosa.
Methods: To begin with, 10 milk samples were collected from different areas of Gilan province. Then, each sample was cultured as well as incubated in MRS Broth medium. Afterwards, for removing the unwanted microorganisms, acidity tolerance and bile site tolerance tests were performed. Microorganisms which could tolerate the conditions were cultured in MRS Agar and were incubated. In the following, to identify the characteristics of those microorganisms, tests such as gram stain, catalase, and carbohydrate fermentation were carried out. In order to detect the microorganisms, first, their DNA’s were extracted through DNA-extraction kit, and then, PCR for 16s rRNA was conducted. Eventually, to measure the effects of harvested probiotics against P.aeruginosa and C.albicans, the well-diffusion method was used. To do so, first, criterion species of C.Albicans (PTCC 5027) and P.aeruginosa (PTCC 1690) were cultured and standard dilution was prepared. Then, the standard dilution of pathogens was inoculated on solid culture medium, and a hole was made in the center of the culture medium. The next step was to prepare a standard dilution of probiotics which was harvested from milk samples, and 50 to 70 μl was added to the hole. This test was reperformed with the difference that this time the standard strain of probiotics was used rather than the harvested one. Finally, samples were incubated for analyzing the results.
Results: Our results indicated that the grown colonies which harvested from milk were the same size, white in color, and were gram positive cocci. Likewise, the result of catalase test was negative, and the results of acidity and bile-salt tests prove that almost %37 of microorganisms tolerated this condition. From nine carbohydrate which were used, the harvested probiotic was capable to ferment six of them including Lactose, Maltose, Mannitol, Ribose, sorbitol, and Glucose, while
Arabinose, Inulin and Raffinose were not fermented. Isolated probiotics were over than %99 similar to Enterococcus Faecalis. Effects of both isolated E.Faecalis and standard strain of E.faecalis showed no harmful impact on C.albicans. At the same time, comparing with C.Albicans, P.aeroginosa was sensitive to E.faecalis. Similarly, standard strain of E.Faecalis and isolated E.Faecalis showed zone of inhibition with diameter of 3.13 mm and 3.86 mm, respectively. Still, there were no observation of P.aeruginosa colonies.
Conclusion: According to our results, we realized that despite the fact that P.Aeruginosa was sensitive to E.Faecalis, C.Albicans showed resistance to E.Faecalis. We also found out that isolated E.Faecalis was more effective in proportion to its standard strain. An interesting point in this study was that different types of probiotics can be effective for eliminating pathogens, unlike other species. Thus, we suggest to test a range of probiotics against quite a few types of pathogens. By doing so, we can use probiotics to purposefully treat infections caused by a specific pathogen, or identify their useful types and use them on food industry to reinforcing the immune system.