NECESSITY OF MICROBIOTA STUDIES AND ESTABLISHMENT OF THE MICROBIOTA BANK IN IRAN

The term human microbiota refers to the population of microorganisms, including bacteria,viruses, fungi, and protozoans, and their genetic material that live on and inside the human organisms[1]. The number of bacteria occupying the human body is estimated to be in the trillions and it is estimated that there are two to four million distinct nonhuman genes in the human body. Our intestine contains more microorganisms, especially bacteria, than all of our other colonized sites combined. There are also populations of bacteria on the skin, in the urogenital tract, mouth, nose, ears, and eyes. The human microbiome modulates many host processes, including metabolism, inflammation and immune and cellular responses. The microbiome has received increasing attention over the last 15 years. For example, numerous studies have reported changes in the gut microbiota during not only obesity, diabetes, and liver diseases but also cancer and even neurodegenerative diseases[2]. Recently, it has become evident that microbiota and particularly gut microbiota modulate the responses to cancer therapy (including chemotherapy, radiotherapy and immunotherapy) as well as susceptibility to toxic side effects[3, 4]. Furthermore, several studies demonstrated that Candida yeast which mostly occur in association with humans, thriving on the mucosal surfaces of the gastrointestinal (GI) and genitourinary tracts and skin could serve an alternative niche for H. pylori (the main cause of gastritis, peptic ulcers and gastric cancer) and may be also reservoir for other fastidious organisms. It is believed that this phenomenon might explain why such fastidious bacteria are able to survive outside the human body and remain highly prevalent in certain populations[5-7]. The human gut microbiota is viewed as a potential source of novel therapeutics such as novel antimicrobials[8] and probiotcs. Between 2013 and 2017, the number of publicatons focusing on the gut microbiota was, remarkably, 12900, which represents four-ffhs of the total number of publicatons over the last 40 years that investgated this topic. probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Historically, conventional probiotic strategies included a phylogenetically limited diversity of bacteria including Bifidobacterium, Lactobacillus species and other lactic acid bacteria (LAB) and some yeast strains. However, therapeutic strategies evolved in the last years with the advent of fecal microbiota transplant (FMT), successfully applied for treating CDI, IBD, and other diseases. Despite the positive outcomes, long-term effects resulting from the uncharacterized nature of FMT are not sufficiently studied. Thus, developing strategies using characterized gut colonizers with identified phylogenetic diversity may be a promising alternative[9]. Microbiota composition is affected by a number of factors including host genetics, diet, ethnicity, geography, age and antibiotics consumption. It is argued that geography is the strongest predictor of the gut microbiota composition. It has been demonstrated that, microbiota are as diverse as human populations. Because of the high diversity of human microbiota worldwide, introduction of healthy but unfamiliar or foreign bacteria native to another population may simply be ineffective in the target population or may even disrupt the indigenous integrity of population-specific indigenous intestinal microbiota, and also give rise to unwanted side effects and even metabolic, epigenetic and carcinogenic complications .In this regard, it is recommended to isolate probiotics from native microbiomes and in the case of efficacy, to use them in the same population[10]. In most of human microbiome projects, the study of the human gut microbiota has been done by metagenomic studies. However, a growing problem is the gaps that remain in metagenomics, which correspond to unidentified sequences that may be correlated with an identified organism. Moreover, the exploration of relations between the microbiota and human health require—both for an experimental model and therapeutic strategies—the growing of microorganisms in pure culture. From 2016, a new high throughput method terms as culturomics render an ever-growing portion of microbiota cultivable and investigable [11, 12]. Culturomics which considered as rebirth of culture in microbiology consists of the application of high-throughput culture conditions to study the human microbiota and uses matrix-assisted laser desorption/ionization– time of flight (MALDI–TOF) or 16S rRNA amplification and sequencing for the identification of growing colonies, some of which have been previously unidentified[13]. Currently culturomics has identfed 1070 different bacterial species and 168 bacteria frst isolated from humans[12]. It is believed that these culturable bacteria could serve as potential sources for delighting new microbiome-based therapeutic approaches and elucidation the real impact of microbiota on human health and diseases.In our country, some public collections of microorganisms have already been established and few of them are members of WFCC (World Federation of Culture Collections). These microorganism banks currently containing strains of archaea, bacteria, filamentous fungi, yeasts and algae mainly from environmental sources and perform scientific research including taxonomic studies and screening of industrially and environmentally significant organisms. Despite the importance of microbiota, no studies have been conducted on the cultivation and maintenance of this vast microbial source in Iran. Accordingly, lunching microbiome biobanks for archiving native microbiome is a promising proposal. Culturing and preserving the Iranian microbiota provides platforms for extending future research about microbiome–human interactions, disease mechanisms, identification of novel drug targets and diseases biomarkers, novel probiotics design, drug discovery, and maintenance of human health.