The average human gastrointestinal tract consists of trillions of bacteria, which comprises of over 400 species. Our body weight carries nearly four pounds of intestinal microflora. In a healthy human intestine, there are more helpful bacteria than bad bacteria or pathogenic ones.
Among those, Lactobacilli are the most beneficial or helpful bacteria. It consists of various species and many strains for each species that can be closely examined through a microscope. Those that are normally found in the human digestive tract are called Lactobacillus acidophilus. Looking closely through a microscope, L. bulgaricus is the common starter in making yogurt. This type of Lactobacillus, after two weeks yogurt consumption, disappears from the intestine. Another helpful bacterium that is normally found in the human intestine and stays for a longer period of time is the L. plantarum.
Lactobacillus genus is the chief representative nonsporing gram-positive rods that can be closely examined through a microscope. Lactobacilli are unable to use oxygen as an electron acceptor due to the reason that it has no cytochrome system. However, these aerotolerant rods make acids from simple carbohydrates to produce lactic acid. Though acidity kills competing bacteria, lactobacilli grow well on this environment. Through the help of a microscope, this helpful bacterium is very visible. In human body, lactobacilli are normally found in oral cavity, intestinal tract, and in the vagina.
This Lactobacillus genus multiplies heavily in the digestive system. While in the mouth, millions of bacteria exist in each milliliter of saliva. The stomach produces hydrochloric acid, and is relative to the rapid movement of food in the small intestines. Both of them contain a few microorganisms. In contrast, the large intestine has massive numbers of microbes, which are more than 100 billion bacteria in every grain of feces (Fecal mass is 40% made up of microbial cell material) if examined through a microscope. Anaerobes of the genera Lactobacillus, Bacteroides and facultative anaerobes, such as E. coli, Enterobacter, Klebsiella, and Proteus populate the large intestine. Most of them help in the enzymatic breakdown of foods and produce vitamins, such as vitamins 131, B2j B6, and B12, folic acid, biotin, and vitamin K useful for the human body.
Lactobacilli convert lactose to lactic acid and because of this, lactose intolerance is successfully managed. Due to lack or dysfunction of the essential enzyme systems, some people cannot metabolize lactose thus suffer in this condition.
Lactic acid lowers the pH level of the intestinal environment to 4 to 5; as a result, it inhibits the growth of putrefactive organisms and E. coli, which require a higher optimum pH of 6 to 7. Under conditions of low oxidation-reduction potential, some of the precarious acids produced during fermentation also possess some antimicrobial activity.
To cultivate species of Lactobacillus chemically, the medium used must be provided with various organic growth factors. Notice through microscope that fastidious organisms require multiple growth elements. Lactobacillus as one of these organisms, sometimes are used to determine the concentration of a particular vitamin in a substance. For microbiological assays (tests), the growth medium contains all the growth requirements of the bacterium (except the vitamin being assayed,) to test substance and the bacterium. To obtain the proportionate growth of bacteria to the amount of vitamins in a medium, test substance and bacterium is combined. The result will produce the amount of lactic acid. With more lactic acid, the more the Lactobacillus cells are able to grow, and more vitamins are present.
