Investigating the effect of kefir products available in the Iranian market on intestinal pathogens

Master's Thesis in Microbial Biotechnology

Abstract

Probiotics are foods that contain living microorganisms that are useful for the body. The microbial balance of the consumer's body. Probiotics are often used in the production of fermented dairy products.

Kefir is a natural probiotic. Paying attention to the microbial and chemical composition of kefir shows that kefir is a complex probiotic containing a large number of bacteria and yeast, which gives this product unique characteristics among other probiotics. Vitamins, minerals, essential amino acids and proteins that are easily digestible. The benefits of consuming kefir in the diet are many, among which we can point out the prevention against some diseases and abnormalities. Measuring the sensitivity of some intestinal pathogenic bacteria such as Escherichia coli O157, Listeria monocytogenes, Vibrio.cholerae, Salmonella.typhi, Shigella sonei, Helicobacter.pylori to the kefir products available in the Iranian market. Using the common porplate method, the samples were examined and the death time graph was drawn for each bacteria. Both kefir products are able to reduce the level of live bacteria. It can be concluded that drinking kefir can be effective in preventing some abnormalities. Key words: probiotics, kefir, sensitivity, intestinal pathogens. rtl;"> 1-1-1- Probiotic

1-1-1-1- History

The origin of the use of fermented dairy products goes back to the beginning of the urbanization process. When, according to different weather conditions, people looked for a way to develop the use of traditional fermented dairy products and kefir sour milk, Kumis [1], Leben [2] and Dahi [3] [1]. Many of these products - which are still widely used in the world - were also used to treat some abnormalities before the recognition and discovery of the existence of bacteria. [2, 3]

At the beginning of the 20th century, the main function of the digestive flora was not well known until Ilya Ilyich Mechinkov or The same Eli Mechinkov[4], the Russian scientist who won the Nobel Prize, usually expressed his opinion as the first person to propose the effect of probiotics. He is actually considered the father of probiotic science. Of course, the word probiotic was never used until 1965, that is, 49 years after the death of Mechinkov. He wrote a book entitled Long Life, and in it he put forward the hypothesis that a series of intestinal bacteria with the production of substances Toxins are the main suspect in the aging process in humans. He believed that the bacterial population living in the human colon produces a series of toxic substances that affect the host's nervous and vascular system, and at the same time, the absorption and circulation of these substances in the blood circulation plays a role in the aging process. His initial proposal was strange: remove and remove the colon! Then, through another hypothesis, he claimed that the health and balance of the digestive environment can be ensured by replacing harmful intestinal bacteria with more beneficial bacterial populations, including fermenting types. In 1908, Mechnikoff claimed a connection between the regular consumption of fermented milk products and the health and longevity of the native populations of Eastern Europe, especially the Bulgarians. After that, he named the bacteria isolated from fermented milk as Lactobacillus delbrueckii subspecies Bulgaricus. [3, 4]

After that, research on the role of lactic acid bacteria in human and animal health began. Tesir's discoveries [5] in 1906 about the presence of Biffidiobacter in the milk consumed by infants, emphasized that bacteria can play a role in health.[5]

Today, for many reasons, including the increase in resistance of bacteria to antibiotics, medical science has turned to more studies and therapeutic use of probiotics. [6]

1-1-1-2- Definition

     The term probiotic[6] means "for life". and the World Health Organization [7] in 2004, refers to this term as "living organisms" that, if consumed continuously, have effective "health-enhancing" effects for their host. These microorganisms are not only not pathogenic, but in principle, they do not lead the body to disease. These organisms can include different genera of bacteria and even yeasts such as Saccharomyces. One of the reasons for using Saccharomyces as a probiotic is that it can pass through the digestive system. Antagonistic interactions have also been observed between Saccharomyces and intestinal pathogens. [8] The acidic environment of the stomach and the initial part of the small intestine is not considered a suitable environment for bacteria, and on the other hand, the rest of the small intestine, especially the large intestine, can be a good host for them. billions, most of these are not pathogenic and the function of some of them is still unknown. The bacterial environment of the intestines is very complex and has the ability of rapid and extensive changes. Often, factors such as diet, stress, antibiotic use and old age can affect the balance of this microbial population. Harmful and non-beneficial species can cause serious injuries. This is why the use of probiotics is increasing today. Most of the microorganisms that are commonly used as probiotics are: lactobacilli, streptococci, and fidobacteria. These three groups of bacteria are the main important compounds in the intestinal digestive system and are known as harmless microorganisms. [9]

According to the above points, probiotics must be microorganisms that:

1- Their usefulness for the host has been proven.

2- They remain alive and active during administration and during passage through the digestive tract until settling in the intestine.

3- Not pathogenic.

4- Can be cultivated easily.

5- Have the ability to connect to the intestinal mucosa tissue in the host body

6- Produce enzymes or physiological substances useful for the host body. [10]

1-1-1-3- The role of probiotics

     Probiotics promote health in several ways. One of their characteristic features is their ability to suppress the growth and activity of pathogenic bacteria. In addition, some probiotics are used to treat or prevent certain diseases [1]. Their beneficial effects depend on the type of bacteria used and the amount of dosage. Probiotics by the individual. Therefore, the results obtained about a probiotic species are not necessarily used for all species [11].

From the theory of probiotics, it may be useful in the treatment of various diseases caused by microorganisms in the body, including some digestive diseases, skin diseases, and some autoimmune diseases. Some specific probiotics are also possible. To play a role in reducing the development of allergy and eczema in children, helping patients reduce the side effects of taking antibiotics, controlling the secretion of some inflammatory substances in the body, preventing urinary infections[7]. In healthy people, probiotic consumption creates and maintains the microbial balance of the body, which means it reduces the number of Coliforms, Clostridia and increases Lactobacilli or Bifidobacteria[12]