**7. The function of microbiome in terms of human health**

When you realize that there are as many microorganisms in the body as there are human cells, the microbiome's importance seems understandable. The human microbiome is diverse at each body site, such as the gut, skin, mouth, and nasal cavities, where each community of microorganisms is unique. The core microbiome of a person is developed during the first years of life, although it can alter over time as a result of several

### *Microbiome - The Power House of Health and Disease DOI: http://dx.doi.org/10.5772/intechopen.106026*

factors such as nutrition, drugs, and environmental exposures. Individual vulnerability to various diseases may be determined by differences in the microbiome, which may lead to varying health outcomes from environmental exposures. A healthy microbiome has been found to play a significant role in maintaining good health [69]. Environmental exposures can also alter a person's microbiome, thereby increasing the risk of acquiring diabetes, obesity, cardiovascular and neurological illnesses, allergies, and inflammatory bowel disease. The human microbiome is primarily concentrated in the stomach. These organisms serve a critical role in maintaining and preserving human health. Previous research on the human microbiome project has shown that alterations in the immunological environment can be connected to a dysbiotic gut flora. Dysbiosis has also been related to life-threatening health disorders such as cancer, cardiovascular disease, bowel inflammatory disease, and difficult-to-treat bacterial infections due to antibiotic resistance [70]. A healthy microbiome is a diverse and abundant one, and everything from our nutrition to our surroundings influences how effectively it performs.

However, antibiotic usage and ultra-processed food consumption, for example, are destroying our gut microbiota, making people more susceptible to infections such as *Clostridium difficile* and other diseases. It's only now becoming obvious how important the link between our microbiomes and our health is. The revelation that we can use our microbiome to help us treat or even prevent disease has been perhaps the most significant development. In the last 20 years, the advent of hyper virulent *Clostridium difficile* strains has resulted in a massive increase in infections, with over 20% of cases

#### **Figure 4.**

*Schematic diagram showing the microbiome implicated in a variety of disorder, including skin, metabolic, and cardiovascular disease, as well as cancer, infection, and neurodegenerative and psychiatric disorders [72].*

now involving germs that are drug resistant. The human genome consists of just 23,000 genes, while the microbiome as a whole contains many millions. Scientists are also looking into using microbiota transplants for a wide range of disorders, such as insomnia, Parkinson's disease, HIV, chronic fatigue, multiple sclerosis, obesity, insulin resistance, metabolic syndrome, and autism [71] (**Figure 4**).

### **8. Antimicrobial resistance**

Microorganisms must discover an optimal strategy to coexist with other microbes in a restricted environment in order to thrive. Microbes compete with one another in their surroundings for limited nutrients and space. As a result, they've devised strategies to regulate their own needs by interacting with other microorganisms. Producing antimicrobial compounds that can hinder or kill another germ is one effective technique to do so. Some microorganisms, on the other hand, have evolved mechanisms to survive in the presence of naturally occurring antimicrobials, allowing them to remain a stable member of a microbial community. Antimicrobial resistance can be inherent or acquired in microorganisms. Intrinsic resistance occurs when a bacteria develops resistance to an antibiotic on its own. Microorganisms have had intrinsic resistance mechanisms for millennia, promoting their co-evolution and integration with microbial communities. Antimicrobial medication development and use to treat and eradicate microbial infections is without a doubt the greatest triumph in contemporary medicine. Penicillin, the first mass-produced antibiotic used on a massive scale around the world, saved millions of lives and paved the way for the discovery and development of hundreds of different antimicrobial medications to combat specific infections. Antimicrobial medications have all come from naturally occurring microbial sources, to which certain microorganisms had already evolved innate resistance.

Microbes have developed acquired resistance to antimicrobial medications as a result of increased use of antimicrobial drugs combined with pre-existing resistance. Antimicrobial resistance (AMR) arises when bacteria, viruses, and fungi grow resistant to antibiotics. As a result, infections may become more difficult to remove. AMR is now considered to be one of the most serious risks to world health, food security, and economic development. According to the World Health Organization, at least 700,000 people die each year from drug-resistant diseases, and this number is expected to climb if adequate interventions are not implemented. The overuse and misuse of antimicrobial therapies in a fast rising global economy and population has resulted in a rise in the rate of AMR cases over the last 20 years. Antimicrobials, which are thought to be a panacea for eradicating illnesses, have fueled the emergence of antimicrobial resistance in bacteria.

### **9. Finding biomarkers in microbiome research**

These types of mechanistic tests are currently being carried out in humans by several investigations. The authors assessed the ability of the individual's blood to create cytokines following several antigen challenges in 500 European-ancestral individuals in the Netherlands, and then linked this with data from their gut metagenome. According to the findings, the yeast *Candida albicans* had a particularly strong influence on the host's TNF-alpha response [73]. These investigations are particularly *Microbiome - The Power House of Health and Disease DOI: http://dx.doi.org/10.5772/intechopen.106026*

relevant when dealing with persons who have naturally occurring genetic knockouts or variant alleles. As has been proven for Parkinson's disease, these human genetic variants may enable microbially caused disease that may be investigated in mice with analogous null or variant genetic changes [74].

Characterizing microbial biomarkers offers a lot of promise for precision medicine, and it's a straightforward method to get microbiome research into clinical practice. For example, we know that bacterial probiotics (living bacteria purposely introduced to an animal to have a therapeutic effect) can be utilized to augment immune checkpoint blockade therapy for melanoma patients based on landmark animal studies [75]. Microorganisms in the gut have been identified as biomarkers for diagnosis that can predict if patients are at risk of developing checkpoint blockade therapy after studying the microbiomes of melanoma patients prior to immune checkpoint blockade medication.-colitis caused by a blockage [76].

These prospective studies are critical for correlating the structure, function, and metabolic products of microbial communities to health consequences. Many ongoing investigations, such as the National Institutes of Health Common Core program. Environmental Influences on Child Health Outcomes (ECHO: https://www.nih.gov/ echo), now provide the infrastructure to sequence healthy, susceptible, and diseased participants to examine how lifestyle and environmental experiences shape the development of immune, endocrine, and neurological conditions. Although single time point investigations of birth cohorts show fascinating statistical relationships [77], longitudinal prospective studies accompanied by mechanistic tests in animal models are needed to determine if a specific microbiome causes disease (**Figure 5**).

#### **Figure 5.**

*The iterative cycle of analysis, interpretation and translational intervention that facilitate moving microbiome research out of correlative observation and into therapeutic treatments [78].*
