Gut Ecology and Health -1

Gut Ecology and Health -1 

The human gut is typically a microbial eco-system with a fascinating diversity of microbial populations, often described as the gut microbiota, gut flora and the gut microbiome. The gut microbiome comprises of various archaeal, bacterial, viral, fungal, and protozoan species that live in a symbiotic relationship in the human gut (Moszak et al, 2020).  

The benefits to the host from the gut microbiome include the biosynthesis of essential vitamins like K and vitamin B, protection from inflammation and pathogenic infections and the conversion of dietary fibres into essential fatty acids (Sherwood et al, 2013).  

Established within two years after birth, the delicate configuration of the human gut microbiota is prone to fluctuations due to factors such as age, diet, and chronic health conditions (Quigley, 2013) and any drastic fluctuation in the gut microbiome, further exerts a definite influence on the host health leading to various metabolic disorders and diseases (Thursby and Juge, 2017).  

Gut Bacterial Diversity 

Of all the microorganisms in the gut, bacteria are the most investigated and ubiquitous. The bacterial florae are described as bacteriome and is classified as those species in the stomach and the intestine. Modern identification of the bacterial florae goes by creation of genetic catalogues of the bacteriome using shotgun metagenomics (Jeannette, 2018).  

Though the gut bacterial species diversity is estimated to stretch from three hundred to one thousand species, only some of them have been elucidated comprehensively (Shanahan, 2002 and Sears, Cynthia 2005). This scientific gap is due to the verity that there are no specific laboratory culture protocols for most of the gut bacterial species yet! 


Recurrent and drastic fluctuations in the gut bacteriome leads to a condition called “Dysbiosis’’, also referred to as ‘Dysbacteriosischaracterized by a reduction in bacterial diversity with a marked decline in the population of beneficial bacteria (Cifone et al, 2017).  

This unfavourable alteration in the bacterial population often results in a concomitant proliferation of pathobionts (Quigley ,2017), a group of symbiotic bacteria that turn pathogenic under specific conditions (Walker, 2017). Indiscriminate usage of antibiotics, dietary habits, malnutrition (Chan et al, 2013), physiological, and psychological stress and alcohol induced hepatitis (Yan et al, 2011), have been identified as significant promoters of dysbiosis. 

Dysbiosis and Diseases 

Dysbiosis causes numerous disorders and chronic diseases of the gut such as obesity, inflammatory bowel disease, and sepsis (Guarner and Malagelada, 2003).  

In the worst scenario, dysbiosis in the stomach, can cause Helicobacter pylori infection resulting in extensive ulceration of the stomach due to the infiltration of the bacteria into the epithelial lining of the stomach. This bacterial infiltration triggers an inflammatory response (Kamboj et al, 2017), injuries the parietal cellscauses excessive release of hydrochloric acid and suppresses production of the mucus (Peptic ulcer disease, 2013).  

Dysbiosis, at times, results in a lethal translocation of the normal gut bacteria due to extrusion of the localized bacterial species into other regions of the intestinal tract within the gut (Faderl et al, 2015). Dysbiosis can also cause Ulcerative colitis and Crohn's disease (Shen et al, 2016). 

Recent studies have elucidated numerous neurologically active compounds synthesized by the gut-bacteriome and their active role in the human neurological response. This neuro-gut microbial link is known as ‘the gut-brain axis’ (Wang et al, 2014) that explicates the role of the gut microbiome in triggering of the signal mechanisms of the enteric nerves through the hypothalamic–pituitary–adrenal (HPA) axis in response to stress situations (Saxena and Sharma, 2016).  

Irritable bowel syndrome is a complication that has documented evidence of change in the luminal and the mucosal microbiome during episodes of stress (Dinan et al, 2015). 

Dietary Manipulations 

Recent studies have established that diet also can be utilized to stabilize the configuration of the gut microbiome in a time bound manner and hence, dietary manipulation is one of the promising and principal therapeutic strategies to restore gut microbial diversity, composition, and stability to reverse dysbiosis towards restoration of health.  



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  1. Sherwood, Linda; Willey, Joanne; Woolverton, Christopher (2013). Prescott's Microbiology (9th ed.). New York: McGraw Hill. pp. 713–21. ISBN 9780073402406. OCLC 886600661 

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  1. Jeannette S. Messer, Eugene B. Chang. Chapter 36 - Microbial Physiology of the Digestive Tract and Its Role in Inflammatory Bowel Diseases. Editor(s): Hamid M. Said, Physiology of the Gastrointestinal Tract (Sixth Edition), Academic Press, 2018, Pages 795-810. 

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  1. W.A. Walker, Chapter 25 - Dysbiosis, Editor(s): Martin H. Floch, Yehuda Ringel, W. Allan Walker, The Microbiota in Gastrointestinal Pathophysiology, Academic Press, 2017, Pages 227-232. 

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  1. Faderl, Martin; Noti, Mario; Corazza, Nadia; Mueller, Christoph (2015). "Keeping bugs in check: The mucus layer as a critical component in maintaining intestinal homeostasis". IUBMB Life. 67 (4): 275–85. doi:10.1002/iub.1374 

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  1. Dinan, Timothy G; Cryan, John F (2015). "The impact of gut microbiota on brain and behaviour". Current Opinion in Clinical Nutrition and Metabolic Care. 18 (6): 552–8. doi:10.1097/MCO.0000000000000221 


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