BIOLOGICAL FUNDAMENTALS AND MOLECULAR MECHANISMS OF MICROBIOTA REGULATION

The human microbiome encompasses diverse microbial communities, including bacteria, archaea, viruses, fungi, phages, and protozoa, located at various anatomical sites in the body, which demonstrate dynamic compositional alterations. The holobiont theory characterizes a living creature not as an independent individual, but as a coherent ecological unit comprised of numerous microorganisms that coexist symbiotically with a host. In this ecologic framework, the evolutionary process demonstrates bidirectional progress not only through the host genome but also through the holobiont's genetic repertoire. Gene transmission in the evolutionary process occurs both vertically and horizontally inside the holobiont. This idea posits that the health, characteristics, and evolutionary journey of the host are intrinsically linked to the myriad of small symbiotic partners it houses. These microhabitats, which coevolve with their hosts, serve as vital for the healthy development of bodily functions and maintenance of normal physiology from birth. Dysbiosis, characterized by disruption of host-microbial homeostasis, has been associated with the etiopathogenesis, aggravation, and progression of numerous illnesses. Illuminating the genetic and biological pathways that sustain host-microbiota will help develop targeted therapeutic strategies by identifying metabolic, genetic, and immunological key points related to the pathogenesis of diseases caused by this imbalance. The historical approaches designed to attain therapeutic results in the host through the regulation of the composition and functions of the human microbiota extend back several centuries. The significant growth in literature and clinical procedures in this field shows its revolutionary therapeutic potential. The advancement and increased availability of multiomic methodologies and technologies for cellular reprogramming of the microbiota have resulted in the establishment of a novel field termed "microbiome engineering." These advancements are anticipated to result in the development of evidence-based, individualized therapy strategies that will reduce the morbidity and mortality linked to various diseases. This section intends to summarize the existing knowledge of the biological and molecular mechanisms that drive microbiota modulation across various organ systems. Additionally, it aims to evaluate future prospects in rapidly evolving fields such as microbiome engineering, focusing on the functional manipulation of microbiota.