The human microbiome refers to the microorganisms that reside in and on human tissues. The intestinal microbiome is the largest and most densely populated microbial community. The small intestine contains trace amounts of microorganisms while the large intestine contains over 300 bacterial species including obligate anaerobes like Bacteroides and Bifidobacterium. The intestinal microbiome aids in digestion, regulates the immune system, controls brain health, and affects overall gut health. Diet, age, genetics, and antibiotic use are some of the main factors that can modify the intestinal microbiome. Diseases caused by intestinal microbes include diarrhea, cholera, shigellosis, and typhoid fever.

1. Topic:
intestinal microbiome
Submitted to:
Dr saghir ahmad
Submitted by
Name :ayesha tahir
Roll number:871
Uni roll number :023822
BS zoology Semester:8

2. HUMAN MICROBIOME
The human microbiome is the aggregate of all microbiota that reside on or within human
tissues and biofluids along with the corresponding anatomical sites in which they reside,[1]
including the skin, mammary glands, seminal fluid, uterus, ovarian follicles, lung, saliva, oral
mucosa, conjunctiva, biliary tract, and gastrointestinal tract.
INTESTINAL MICROBIOME:
Intestinal microbiota,flora, or microbiome are the microorganisms including bacteria, archaea
and fungi that live in the intestinal tracts of humans and other animals. The gastrointestinal
metagenome is the aggregate of all the genomes of gut microbiota. The intestine is the main
location of human microbiota.
 Intestine is the main location of human microbiota
 Fecel material may consist of bacteria and other microorganisms.
 Over 300 different bacterial species have been isolated from human feces.
Intestinal micrbiome consist of:
 Stomach
 Large intestine
 Small intestine

3. Small intestine
 Trace amount of micro organisms are present due to proximity and influence of the
stomach
 Bacterial flora provide regulatory signals and enables the development of utility of the
gut.
 Gram-positive cocci and rod-shaped bacteria are the predominant microorganisms
found in the small intestine. However, in the distal portion of the small intestine alkaline
conditions support gram-negative bacteria of the Enterobacteriaceae.
 The bacterial flora of the small intestine aid in a wide range of intestinal functions.
Large intestine

4.  About 99% of large intestine are made up of the obligate anaerobes'bacteriods and
bifidobacterium.
HOW DOES THE MICROBIOME AFFECT NORMAL HOST PHYSIOLOGY?
As your microbiome grows, it affects your body in a number of ways, including:
Digesting breast milk:
Some of the bacteria that first begin to grow inside babies’ intestines are called Bifidobacteria.
They digest the healthy sugars in breast milk that are important for growth.
Digesting fiber:
Certain bacteria digest fiber, producing short-chain fatty acids, which are important for gut
health. Fiber may help prevent weight gain, diabetes, heart disease and the risk of cancer.
Helping control your immune system:
The gut microbiome also controls how your immune systemworks. By communicating with
immune cells, the gut microbiome can control how your body responds to infection,
Helping control brain health:
New research suggests that the gut microbiome may also affect the central nervous system,
which controls brain function.
Affects Gut Health
It control gut health by communicating with the intestinal cells, digesting certain foods and
preventing disease-causing bacteria from sticking to the intestinal walls.
WHAT FACTORS MODIFY THE INTESTINAL MICROBIOME IN THE NORMAL STATE?
Age,,host genetics, diet and antibiotic use all appear to modify the intestinal microbiome.
Age
The microbiome evolves quickly in early life, and is initially characterized by relatively low
diversity and instability.
Infants born vaginally are initially colonized with vaginal microbiota, such as Lactobacillus and
Prevotella, whereas those born by caesarian section are initially colonized by skin microbes.

5. In the first year of life, breastfed infants have an increased proportion of Bifidobacteria and a
decreased proportion of anaerobic organisms relative to formula fed infants. Some
Bifidobacteria have specialized enzymes that allow them to metabolize human milk.
Adults in contrast possess a greater number of genes for dietary folate use. The microbiome
shifts again with the introduction of solid foods and, by around age 3, children have a relatively
stable, adult-like intestinal microbiome.
It appears that with age, the proportions of many members of the Firmicutes family,
bifidobacteria and Faecalibacterium prausnitzii decrease, whereas proportions of E. coli, other
Proteobacteria and staphylococci increase.
Host genetics
Family members have been observed to have more similar microbiota than unrelated
individuals, raising the possibility that genetics may shape the microbiome. A recent study
examining fecal samples from 977 individuals including from both monozygotic and dizygotic
twin pairs showed that microbiomes were more similar for twins than for unrelated individuals
and more similar for monozygotic than dizygotic twins.
Diet
One of most important modifiers of the intestinal microbiome appears to be diet, both shaping
its composition and functional metabolism. An experiment show that the intestinal microbiota
of children living in rural Burkina Faso differed significantly from children living in Florence, Italy.
The microbiota of the children in Burkina Faso, who ate a high fiber diet rich in carbohydrates
and non-animal protein, had greater microbial richness, greater abundance of Prevotella with
lower abundance of Bacteroides, and seemed to produce more short chain fatty acids — likely
reflective of an enhanced ability to break down fiber, starch, oligosaccharides and
carbohydrates from a diet of whole grains that escape digestion in the small intestine. The
European children in contrast ate a diet high in sugar, starch, animal protein, fat and low in
fiber.
Antibiotics
In any intestinal infection the microbiome has been changed due to invading of pathogenic
microorganisms, so the antibiotics help the body to maintains its normal microbiome in
intestine by killing the pathogenic microbes. Beneficial microbes also effected by antibiotics but
after some time they can attain its normal population.
DISEASEBY MICROBES IN INTESTINE:

6. Diarrhea
Diarrhea is loose, watery stools (bowel movements). You have diarrhea if you have loose stools
three or more times in one day. Acute diarrhea is diarrhea that lasts a short time. It is a
common problem. It usually lasts about one or two days, but it may last longer.Common
bacteria that cause diarrhea include Campylobacter link, Escherichia coli link (E. coli),
Salmonella link, and Shigella link.
Cholera
Cholera is an infectious disease that causes severe watery diarrhea, which can lead to
dehydration and even death if untreated. It is caused by eating food or drinking water
contaminated with a bacterium called Vibrio cholera.
Shigellosis
Shigella infection (shigellosis) is an intestinal infection caused by a family of bacteria known as
shigella. The main sign of shigella infection is diarrhea, which often is bloody. Shigella is very
contagious.
Typhoid fever
Typhoid fever is a bacterial infection that can spread throughout the body, affecting many
organs. Without prompt treatment, it can cause serious complications and can be fatal. It's
caused by a bacterium called Salmonella typhi, which is related to the bacteria that cause
salmonella food poisoning.
How Can You Improve Your Gut Microbiome?
There are many ways to improve your gut microbiome, including:
Eat a diverse range of foods:
This can lead to a diverse microbiome, which is an indicator of good gut health. In particular,
legumes, beans and fruit contain lots of fiber and can promote the growth of
healthy Bifidobacteria
Eat fermented foods:
Fermented foods such as yogurt, sauerkraut and kefir all contain healthy bacteria,
mainly Lactobacilli, and can reduce the amount of disease-causing species in the gut. Limit
your intake of artificial sweeteners:

7. Some evidence has shown that artificial sweeteners like aspartame increase blood sugar by
stimulating the growth of unhealthy bacteria like Enterobacteriaceae in the gut microbiome.
Eat prebiotic foods:
Prebiotics are a type of fiber that stimulates the growth of healthy bacteria. e.g yogurts
Breastfeed for at least six months:
Breastfeeding is very important for the development of the gut microbiome. Children who are
breastfed for at least six months have more beneficial Bifidobacteria than those who are bottle-
fed.
Take antibiotics only when necessary:
Antibiotics kill many bad and good bacteria in the gut microbiome, possibly contributing to
weight gain and antibiotic resistance. Thus, only take antibiotics when medically necessary