The human body is host to trillions of microorganisms. These organisms colonize different parts of the body, including the mouth, skin, nose, and gut. As many would think of these germs as harmful, the fact of the matter is, not all of them are harmful. In fact, some microbes that colonize humans are commensal and others co-exist in a mutualistic relationship beneficial to both.

These microbes, including bacteria, fungi, viruses, and a few protozoans collectively form a microbiome in the host body. This microbiome is beneficial to the immune system as well as acts as an important influencer to the metabolism. Different microbes guest different parts of the body.

Microbiome On Skin

Skin is the largest organ in the human body and the first point of contact. A plethora of bacteria and fungi colonize the skin. They help protect against any pathogenic organism in the vicinity of the skin. For example, Bacillus subtilis, a bacteria that thrives on human skin produces bacitracin on the skin. It is a toxin that helps fight against other microbes. A few other bacteria and fungi colonize specifically around the sebaceous glands in order to form a protective film against pathogenic attacks.

Microbiome In Digestive System

It is the digestive system that hosts more than 90% of the total microbiome population in the human body. Beginning right from the mouth, down the esophagus, until the intestines and the anus, these microbes colonize and help with metabolism in numerous ways.

  • Oral Microbiome

Microbial habitats in the mouth include teeth, gums, gingival sulcus, tongue, and cheeks. There are more than 600 species comprising the oral microbiome. The oral microbiome is helpful in fighting bad breath, and dental problems, and enhancing the digestive process. For example, Streptococcus, Actinomyces, and Lactobacillus secrete acid, leading to an acidic pH. This acid helps with the breakdown of starch in food. Another benefit of this acidic pH is that it helps kill a number of other harmful bacteria. There are other examples of bacteria that form a film around the colonized part and protect against pathogenicity. Having said that, there have been studies to show that the commensal behavior of these microbes can change to pathogenicity owing to changes in their environment or the host’s personal hygiene. That is why maintaining personal hygiene and good oral health is so important. Not just for the host but the microbiome in the oral cavity as well.

  • Microbiome In Gut

The largest and most complex microbiome in the human body is present in the gut. These microbes typically act as catalysts or promoters of good metabolism. Apart from promoting metabolism, these also enhance the immunity of the human body. The microbiome of one host is different from the other owing to the difference in atmosphere, personal hygiene, environment, and topographical and geographical variations. A study of the microbiome in the gut is very crucial in deciding the dietary and drug-related prescriptions of an individual. Maintaining a good microbiome in the gut is crucial to the healthy functioning of all the organ systems in the body. This article explains the importance of maintaining a gut microbiome. For example, some bacteria in the intestines produce fatty acids and peroxides, and specific bacteriocins that can inhibit or kill potentially pathogenic bacteria.

Microbiome In The Nasal Cavity

The identification of the species present inside the nasal cavity is still under study. There are no numbers to specify how many species are present inside the nasal cavity. The nasal microbiome has been identified to contain a few aerobic and anaerobic bacteria apart from some viruses and discrete species of fungi. Though very little is known about the nasal microbiota, it has been established that they influence the reaction between the mucosal and systemic immune systems. Different studies reveal that there are no signs of any colonization of the gram-negative bacteria in the nasal cavity which are far more dangerous than any disease-causing organisms.

Microbiome In The Reproductive Tract

For successful reproduction, a healthy microbiome in the reproductive tract is very crucial. Colonies of different species exist throughout the length of the reproductive tract in variable compositions. These colonies are very crucial to reproductive cyclicity, gametogenesis, pregnancy, and successful delivery of newborns. These microbiomes are equally important for both males and females.

Just how important the interaction between humans and microbes is can now be easily understood. Considering the abundance and influence of these microbes inside the human body, one may think that not all are so bad after all.