A systematic review is a rigorous research method that involves a systematic approach of collecting, assessing, and synthesizing relevant unpublished, and published literature to answer a well-defined research question.

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By
NWACHUKWU CHIZOBA GIFT
20171048225
DEPARTMENT OF MICROBIOLOGY
SCHOOL OF BIOLOGICAL SCIENCE (SOBS)
FEDERAL UNIVERSITY OF TECHNOLOGY,
OWERRI
P.M.B. 1526 OWERRI, IMO STATE
Seminar Presentation

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Seminar Topic:
GUT MICROBIOME IMPACT ON
HUMAN GASTROINTESTINAL
TRACT

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Abstract
The purpose of this seminar is to examine how the gut microbiome
impacts the human gastrointestinal tract. The paper described the gut
microbiome as the micro-organisms (bacteria, archaea, lower and
higher eukaryotes, and viruses) as well as their genome (i.e., genes)
that comprise them and the surrounding environmental factors that
influence the collection of microbes, their genes, and their products
that colonise our body since birth. While some bacteria are associated
with disease, others are actually extremely important for your immune
system, heart, weight, and many other aspects of health. This seminar
concluded that the gut microbiome impacts the human gastrointestinal
tract because they are essential to helping humans absorb nutrients.
The gut microbiome has a direct influence on the immune system and
the body’s ability to deal with disease and infection. It further
concludes that factors such as antibiotic therapies poor diet,
psychosocial stress, and direct exposure to pathogenic organisms can
all affect the gut microbiome. Lastly, the study concluded that
imbalances in the gut microbiome in the human gastrointestinal tract
could increase the risk of certain diseases and conditions.

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CHAPTER ONE
The human gastrointestinal tract (GITract) is composed of a variety of
organs, each with varying internal environments. One of the main
components of the GITract is the stomach. The stomach connects to the
small intestine, which in turn connects to the large intestine. Within these
environments, around one quadrillion microbes live and thrive;
collectively, they are referred to as the gut microbiome.
The gut microbiome is the collection of microbes, their genes, and their
products that colonise our body since birth and are transferred vertically.
The highest microbial numbers are found in the gut. These microbiomes
consist of bacteria, viruses, protozoa, archaea, and eukaryotes. With over
one quadrillion microbes in and on our bodies, these microscopic
organisms play a significant role in our health both positively and
negatively.
This seminar paper will examine how the gut microbiome impacts the
human gastrointestinal tract (GI tract).
Introduction

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Objective of the Seminar Paper
The specific objective of this seminar paper is to examine
how the gut microbiome impacts the human gastrointestinal
tract (GI tract).
To understand the impact of the gut microbiome on the
gastrointestinal tract of the human body, it is important,
however, to have an understanding of: the following
1. Meaning of gut microbiome.
2. Overview the human gastrointestinal tracts.
CHAPTER ONE

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 Microbiome refers to the microorganisms (bacteria,
archaea, lower and higher eurkaryotes, and viruses)
found in the gut as well as their genome (i.e., genes)
that comprise them and the surrounding
environmental factors that influence them.
 Environmental exposures and diet can change one’s
microbiome to be either beneficial to health or place
one at greater risk for disease. This means that the
gut microbiome consists of microbes that are both
helpful and potentially harmful.
CHAPTER TWO
Background Information: Meaning of Gut
Microbiome

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 In a healthy body, pathogenic and symbiotic
microbiota coexist without problems. Most
Microbiome are symbiotic (where both the human
body and microbiota benefit) and some are
pathogenic (promoting disease).
 But if there is a disturbance in that balance due to
infectious illnesses, certain diets, or the prolonged
use of antibiotics or other bacteria-destroying
medications, dysbiosis occurs which stops these
normal interactions. As a result, the body may
become more susceptible to disease.
Meaning of Gut Microbiome
continued:
CHAPTER TWO: Background
Information

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 The gastrointestinal tract (GI tract) is the system
of organs within multicellular animals that takes
in water and food, extracts energy and nutrients
from the food, and expels the remainder as waste. It
can also be called the digestive tract, alimentary
canal, or gut. The major functions of the GI tract are
digestion and excretion.
 In humans, the gastrointestinal tract is a long tube
with muscular walls comprising four different layers:
inner mucosa, submucosa, muscularis externa, and
the serosa. It is the contraction of the various types
of muscles in the tract that propel the food.
Overview Human Gastrointestinal
Tract:
CHAPTER TWO: Background
Information

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Overview Human Gastrointestinal Tract
Continued:
Conceptual Review
The GI tract can be
divided into an upper
and a lower tract.
The upper GI tract
consists of the mouth,
pharynx, esophagus,
and stomach.
The lower GI tract is
made up of
the intestines and the
anus.

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CHAPTER THREE
Firmicutes:
Firmicutes is also a
highly abundant
phylum of Gram-
positive bacteria that
usually have round
(cocci) or rod-like
(bacillus) shapes.
They are known for
their ability to carry
out anoxic
Microbial Species that Forms the Gut
Microbiome
Firmicutes

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CHAPTER THREE
Bacteroidetes:
Bacteroidetes is a
highly abundant
phylum of Gram-
negative, anaerobic,
rod-shaped bacteria
that are abundant in
the short intestines
because of their
resistance to bile.
Microbiome
Bacteroidetes

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CHAPTER THREE
Proteobacteria:
Proteobacteria is a phylum
of gram-negative bacteria
that include some famous
microbes such
as Escherichia coli (E.
coli), Salmonella and
Helicobacter.
Proteobacteria are known
for their nitrogen fixing
activity, which is the ability
to make inorganic
compounds from gaseous
Microbiome
Proteobacteria

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CHAPTER THREE
Actinobacteria:
Actinobacteria is a
phylum of Gram-positive
aerobic or anaerobic
intestinal bacteria that
are known for their
ability to produce
antibiotics such as
actinomycin and
streptomycin.
Microbiome
Proteobacteria

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CHAPTER THREE
Distribution of Gut Microbiome in the GI Tract
The human gastrointestinal
tract (GIT) is composed of a
variety of organs, each with
varying internal environments.
One of the main components
of the GIT is the stomach,
which is an acidic, aerobic
environment. The stomach
connects to the small intestine,
which in turn connects to the
large intestine, and both are
lined with thick mucosal layers.
Within these environments,
around one quadrillion
microbes live and thrive;
collectively, they are referred to
as the gut microbiome. These
microbes consist of bacteria,
viruses, protozoa, archaea and

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CHAPTER FOUR
Gut Microbiome Impact On Gastrointesital
Tract
1. Digestion:
 The gut microbiome plays an active role in digestion of the
carbohydrate, fat and protein components of food.
 They play a particularly important role in digestion of dietary
fibre to yield short-chain fatty acids (SCFA) such as acetate,
propionate, and butyrate. Propionate is thought to play an
important role as a satiety molecule, with the ability to
contribute to the switching off of hunger, while butyrate
promotes programmed cell death (apoptosis) in malignant
epithelial cells lining the large intestine, thereby reducing the
risk of bowel cancer.
 The digestion and fermentation of dietary fibre by the gut
microbiome yields large quantities of gasses such as
odourless methane, carbon dioxide and hydrogen, together

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CHAPTER FOUR
Tract
2. Vitamin Biosynthesis:
 The Gut microbiome carry out biosynthesis on
essential vitamins required for health and survival
since Human cells and tissues are unable to
synthesise the vitamines directly.
 For example, Richin Bifidobacteria, Lactobacilli
and E coliis able to synthesise many of the water-
soluble vitamins, including key B vitamins – such
as folic acid (B9) riboflavin (B2) biotin (B7),
cobalamin (B12), nicotinic acid (B3), panthotenic
acid (B5), and thiamine (B1) – together with
essential fat-soluble vitamins, such as the vitamin

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CHAPTER FOUR
Tract
3. Immune Modulation:
 The Gut microbiome directly influences the body’s
ability to deal with disease and infection.
 Breast milk contains a variety of ‘friendly’ probiotic
bacteria (bacteria that promote health)
including Lactobacillus and Bifidobacterium speci
es, which are known to enhance both gut and
systemic health.
 However, a healthy population of probiotic
bacterial species is generally associated with a
fine-tuned immune system and a general anti-
inflammatory environment.

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CHAPTER FOUR
Tract
4. Immune System Maturation :
 Another impact that gut microbiota provides on
gastrointestinal tract was revealed by an
examination of the T-helper 17 (Th-17) cells in
microbe-free mice. A study conducted more than
10 years ago found that Segmented Filamentous
Bacteria are needed for the formation of Th-17
cells.
 Th-17 cells are a type of white blood cell that
causes other components of the immune system
to react and eliminate an infectious pathogen.

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CHAPTER FOUR
Tract
5. Prevention of Pathogenic
Infection:
 Our gut microbiome resists pathogens through
two primary means: direct interaction with
pathogens, or inducing our immune system to
eliminate the pathogens. The direct interactions
with pathogens includes producing metabolic
products that inhibit the growth of pathogens or
their ability to invade our cells.
 As for stimulating our own immune system to
attack pathogens, gut bacteria can induce

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CHAPTER FOUR
Tract
5. Prevention of Pathogenic
Infection:
 Our gut microbiome resists pathogens through
two primary means: direct interaction with
pathogens, or inducing our immune system to
eliminate the pathogens. The direct interactions
with pathogens includes producing metabolic
products that inhibit the growth of pathogens or
their ability to invade our cells.
 As for stimulating our own immune system to
attack pathogens, gut bacteria can induce

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CHAPTER FOUR
Tract
6. Dysbiosis and Infection:
 The use of antibiotics disrupts the natural
balance of the gut microbiome, potentially
reducing populations of friendly bacteria
and allowing potentially pathogenic
bacteria such as C difficile to grow
unchecked. This means that disturbing
the gut microbiome with antibiotics can
also lead to disease, including infections
that become resistant to antibiotics.

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CHAPTER FOUR
Tract
6.b. Dysbiosis and Disease:
 Gut microbiome in the
gastrointestinal system play a role
in developing gut conditions,
including inflammatory bowel
diseases (IBD), such as Crohn’s
disease and ulcerative colitis. Low
microbial diversity in the gut also
has links to obesity and type 2

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CHAPTER FIVE:
In conclusion:
 The gut microbiome is a large collection of
symbiotic microbes residing in the gut totaling
over a quadrillion cells and more than 100
bacterial species.
 This community of micro-organisms living in
the gastrointestinal tract exerts powerful and
diverse effects on human physiology, ranging
from many benefits for metabolism, digestion,
immune system, and dietary health.
 Gut microbiomes are essential to helping
humans absorb nutrients.
Summary and Conclusion

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4
CHAPTER FIVE:
 Gut microbiome directly influences the
immune system and the body’s ability to deal
with disease and infection.
 Factors such as antibiotic therapies poor diet,
psychosocial stress and direct exposure to
pathogenic organisms can all affect the gut
microbiome.
 Unfortunately, imbalances in the gut
microbiome in the human gastrointestinal tract
could increase the risk of certain diseases and
conditions.
Summary and Conclusion continued

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References
Barras, C. (2019). Your mystery microbiome. New Scientist; 242: 3225, 28-31.
Marchesi, J. R., & Ravel, J. (2015). The vocabulary of microbiome research: a
proposal. Microbiome, 3, 31. https://doi.org/10.1186/s40168-015-0094-
Knight, J. et al (2019). Gastrointestinal tract 6: the effects of gut microbiota on
human health. Nursing Times [online]; 115: 11, 46-50.
Yang X et al (2009)/More than 9,000,000 unique genes in human gut bacterial
community: estimating gene numbers inside a human body. PloS ONE; 4:
6, e6074.
Das A et al (2016).Xenobiotic metabolism and gut microbiomes. PLoS ONE;
11: 10, 1-26.
Ojo-Okunola A et al. (2018). Human breast milk bacteriome in health and
disease. Nutrients, 10: 11, 164.
Silverthorn, D. (2004). Human Physiology: An Integrated Approach, 3rd ed.
Benjamin Cummings.
Zimmermann, M. et al (2019). Mapping human microbiome drug metabolism by
gut bacteria and their genes. Nature; 570: 7762, 462-467.

A systematic review is a rigorous research method that involves a systematic approach of collecting, assessing, and synthesizing relevant unpublished, and published literature to answer a well-defined research question.

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