**4. Microbiota benefits of the body**

The microbiome is essential for human development, immunity and nutrition. Microbiota boost the immune system, break down potentially harmful dietary components, and manufacture vitamins and amino acids such vitamin B and vitamin K [25]. The major enzymes required for the formation of vitamin B12 are exclusively present in bacteria, not plants or mammals [26]. Bacteria living in and on the human body are not always invaders but beneficial colonizers too. Sugars like table sugar and lactose (milk sugar) are quickly absorbed in the upper portion of the small intestine, while more complex carbs like starches and fibers are more difficult to digest and may end up in the large intestine. By creating digestive enzymes, the microbiota aids in the breakdown of these substances. Short chain fatty acids (SCFA) are produced when indigestible fibers are fermented, and they can be utilized by the body as a food source as well as play a role in muscular performance and possibly the prevention of chronic diseases including cancer and bowel disorders. SCFA has been demonstrated to be effective in the treatment of ulcerative colitis, Crohn's disease, and antibiotic-associated diarrhea in clinical trials [25].

Autoimmune diseases like diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, and fibromyalgia have been linked to microbiota dysfunction. Microbes that cause disease build up over time, altering gene activity and metabolic processes, leading in an aberrant immune response to chemicals and tissues that are usually present in the body. A healthy person's microbiota will also defend them from harmful organisms that enter the body by drinking or eating polluted water or food such as

*Prevotella*, *Ruminococcus*, *Bacteroides*, and *Firmicutes* are large families of bacteria found in the human stomach. Anaerobic bacteria such as *Peptostreptococcus*, *Bifidobacterium*, *Lactobacillus*, and *Clostridium* can be found in the colon due to the low oxygen environment [27]. These microbes are thought to prevent harmful bacteria from overgrowing by competing for nutrition and attachment sites on the mucus membranes of the gut, which are a significant site of immune activation and antimicrobial protein production [28, 29]. Autoimmune diseases appear to be passed in families not by DNA inheritance but by inheriting the family's microbiome. Recent studies on gut microbiota modulation suggest that probiotics should be used in the treatment of patients with severe COVID-19 infection, according to the National Administration of Traditional Chinese Medicine and China's National Health Commission [30]. Probiotics are used to prevent secondary bacterial infection and maintain intestinal microbiota balance.
