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1.  Environmental microbiology is the study of the
composition and physiology of microbial communities in
the environment. The environment in this case means
the soil, water, air and sediments covering the planet and
can also include the animals and plants that inhabit
these areas.
Environmental microbiology also involves:
 Microbial interaction and interaction with
macroorganisims.
 Population biology of microorganisms.
 Microbial communities genetic and evolutionary processes.
 Element cycles and biogeochemical processes.
 Microbial life in extreme and unusual environment

2. Microbial habitats:Microbes are found in just about every
kind of habitat.Microbes are incredibly diverse thriving in
environments from the very cold to the extremely hot. They
are also tolerant of many other conditions such as limited
water availability high salt content and low oxygen levels.
Not every microbe can survive in all habitats.
Types of microbial habitats:
Terrestial(soil ) microbial habitats.
Aquatic(water) microbial habitats.
Microbial Habitats in Other Organisms.
air microbial habitat.

3.  Soil Microbial Habitats
 Only one percent of microbes that live in soil have been
identified.These organisms take part in the formation of soil
and are essential components of their ecosystems.Bacteria
and fungi that live in soil feed mostly on organic matter such
as other plants and animals. These microbes are very
sensitive to their local environment. Factors such as the
levels of carbon dioxide and oxygen the pH moisture and
temperature all affect the growth of microbes in the soil.

4.  Water Microbial Habitat
 Microbes live in both fresh and salt water.These organisms
include microscopic plants and animals as well as bacteria
fungi and viruses.As with other microbes the ones that live in
water are adapted to the specific conditions of their
environment.Habitats range from ocean water with an
extremely high salt content to freshwater lakes or rivers
 Microbial Habitats in Other Organisms. Microbes also live on
other organisms.As with the ones found on people these
microbes can be harmful or beneficial to the host. Example:
Bacteria grow in nodules on the roots of pea and bean plants.
These microbes convert nitrogen from the air into a form that
the plants can use.In many ways animals and plants have
evolved as habitats for the millions of microbes that call them
home.

5. WATER AS MICROBIAL HABITAT
Water is essential to life, but many people do not have access
to clean and safe drinking water and many die of waterborne
bacterial infections.

6.  The most important bacterial gastrointestinal diseases
transmitted through water are cholera, salmonellosis and
shigellosis. These diseases are mainly transmitted through water
(and food) contaminated with feaces of patients.
 Drinking water can be contaminated with these pathogenic
bacteria, and this is an issue of great concern. However, the
presence of pathogenic bacteria in water is sporadic and erratic,
levels are low, and the isolation and culture of these bacteria is
not straight-forward.
 For these reasons, routine water microbiological analysis does not
include the detection of pathogenic bacteria. However, safe water
demands that water is free from pathogenic bacteria.

7.  Coliforms are a broad class of bacteria found in our environment,
including the feaces of man and other warm-blooded animals
 The presence of coliform bacteria in drinking water may indicate
a possible presence of harmful, disease-causing organisms.
 They are defined as rod-shaped Gram-negative non-spore
forming and motile or non-motile bacteria which can ferment
lactose with the production of acid and gas when incubated at
35–37°C.
 Coliforms can be found in the aquatic environment, in soil and on
vegetation; While coliforms themselves are not normally causes
of serious illness, they are easy to culture, and their presence is
used to indicate that other pathogenic organisms of feacal origin
may be present.

8. A good bacterial indicator of fecal pollution should fulfill the
following criteria:
 (1) exist in high numbers in the human intestine and feaces
 (2) not be pathogenic to humans
 (3) easily, reliably and cheaply detectable in environmental
waters.
 (4) does not multiply outside the enteric environment
 (5) in environmental waters, the indicator should exist in greater
numbers than eventual pathogenic bacteria

9. Bacteria Disease/ infection Symptoms
Aeromonas Enteritis Very thin, blood- and mucus-
containing diarrhea
Campylobacter jejuni Campilobacteriose Flue, diarrhea, head- and
stomachaches, fever, cramps and
nausea
Escherichia coli Urinary tract infections,
neonatal meningitis,
intestinal disease
Watery diarrhea, headaches, fever,
homiletic uremia, kidney damage
Plesiomonas shigelloides Plesiomonas-infection Nausea, stomachaches and watery
diarrhea, sometimes fevers,
headaches and vomiting
Typhus Typhoid fever Fevers
Salmonella
Salmonellosis Sickness, intestinal cramps,
vomiting, diarrhea and sometimes
light fevers
Streptococcus (Gastro) intestinal disease Stomach aches, diarrhea and
fevers, sometimes vomiting
Vibrio Cholera Heavy diarrhea
Bacteria Found In Surface Water

10. Microorganisms Disease Symptoms
Amoeba Amoebic
dysentery
Severe diarrhea, headache,
abdominal pain, chills,
fever; if not treated can
cause liver abscess, bowel
perforation and death
Cryptosporidi
um parvum
Cryptosporidiosis Feeling of sickness, watery
diarrhea, vomiting, lack of
appetite
Giardia Giardiasis Diarrhea, abdominal cramps,
flatulence, belching, fatigue
Toxoplasm
gondii
Toxoplasmosis Flu, swelling of lymph glands
With pregnant women subtle
abortion and brain infections
Protozoa Found in Surface Water

11.  Hepatitis A: inflammation
and necrosis of liver
 Norwalk-type virus: acute
gastroenteritis
 Rotaviruses: acute
gastroenteritis, especially in
children
 Enteroviruses: many types
affect intestines and upper
respiratory tract
 Reoviruses: infects
intestines and upper
respiratory tract

12. SOIL MICROORGANISMS AND THEIR FUNCTIONS
BACTERIA
They are decomposers, eating dead plant material
and organisms' waste. Do you know what soil
smells like? Well actinomycetes, a unique type of
bacteria, cause that smell, and it is a good sign of
healthy soil. Actually, people have been smelling
soil for many, many years as a way to judge if the
land is good for planting [Nitrogen-fixing bacteria
form symbiotic associations with the roots of
legumes like clover and lupine, and trees such as
alder and locust.

13. FUNGI
 Fungi are organisms. They are not plants, nor are they
animals. They group themselves into strings called
hyphae. The hyphae then form groups called mycelium.
 They are helpful but could also be harmful to soil
organisms. Fungi are helpful because they have the
ability to break down nutrients that other organisms
cannot.
 Fungi can attach themselves to plant roots. This is a
good relationship called mycorriza.
 The fungi help the plant by giving it those needed
nutrients, and the fungi get food from the plant, the
same food that plants give to humans. On the other
hand, fungi can get food by being parasites, attaching
themselves to plants or other organisms, but for selfish

14.  Are organisms that have only one cell, and are
microscopic, but larger than bacteria.
 They are grouped by the ways they move: amoeba use a
psuedo(fake) foot, ciliates have cilia (short hair) and
move them very fast, and flagellates have one or
moreflagella (whips) and move them very fast.
 Protozoa eat bacteria which actually helps keep the
bacteria population growing. Protozoa help other soil
organisms and plants by releasing a usable form of
nitrogen into the soil. They release the excess nitrogen
in the form of ammonium (NH4+). This usually occurs
near the root system of a plant.
 Another role that protozoa play is in regulating bacteria
populations. Predatory nematodes may regulate
populations of bacterial-and fungal-feeding nematodes,
thus preventing over-grazing by those groups.

15. MICROBIOLOGY OF AIR
Of all environments, air is the simplest one and it occurs
in a single phase gas. Various layers can be recognized
in the atmosphere up to a height of about 1000km. The
layer nearest to the earth is called as troposphere. This
troposphere is characterized by a heavy load of
microorganisms. The atmosphere as a habitat is
characterized by high light intensities, extreme
temperature variations, low amount of organic matter
and a scarcity of available water making it a non
hospitable environment for microorganisms and
generally unsuitable habitat for their growth.
Nevertheless, substantial numbers of microbes are
found in the lower regions of the atmosphere. The study
of these microbes in air is called as Aero Microbiology.

16. Disease caused by air borne microbes:
Bacterial Diseases
• Brucellosis:
Brucella suis it is mainly an occupational disease among
veterinarian, butcher and slaughter house workers.
• Pulmonary Anthrax:
Bacillus anthracis is the causative agent. Transmission is
mainly by inhaling the dust contaminated by animal products.
• Diseases Caused by Streptococcus Pyogenes:
A number of diseases are caused by Streptococcus pyogenes
which is mainly transmitted through air. Diseases Caused by
Streptococcus pyogenes occur in the throat, skin, and
systemically.
• Rheumatic Fever: This is upper respiratory tract infection by S.
pyogenes Characterized by inflammation and degeneration of
heart valves.
·

17. • Streptococcal Pneumonia:
It is of major occurrence among the bacterial pneumonia. Causative agent is
Streptococcus pneumonia
• Meningitis :
Haemophilus influenzae causes meningitis in children between 6 weeks
and 2 years of age.
• Diptheria:
Diphtheria is mainly contracted by children. Infection of the tonsils, throat and
nose and generalized toxemia are the symptoms. The causative agent is
Corynebacterium diphtheria
• Tuberculosis:
Pulmonary tuberculosis is a severe respiratory disease. Loss of appetite,
fatigue, weight loss, night sweats and persistent cough are some of the
symptoms. Causative agent is Mycobacterium tuberculosis
• Legionellosis:
It is a type of branchopneumonia. Legionella pneumophila is the causative
agent. It occurs in natural water. At times it enters and proliferates in cooling
tower, air cooler and shower bath. Spraying and splashing of water containing
pathogen may produce aerosols which are disseminated in air.

18. It consists of many types. They are following
• Cryptococcosis:
Leads to mild pneumonitis. Causative agent is the yeast Cryptococcus
neoformans. It is a soil saprophyte. Infection is acquired by inhalation of soil
particles containing the causative agent.
• Blastomycosis:
Formation of suppurative and granulomatous lesions in any part of the body.
Blastomyces dermatitis is the causative agent. It is a soil borne fungus and
hence inhalation of soil particles containing the fungus produces the infection.
• Coccidiodomycosis:
Infection may not be apparent but in severe cases it is fatal. Usually infection
leads to self-limited influenza fever known as valley fever or desert rheumatism.
Causative agent of the disease is a soil fungus, Coccidioides immitis. Inhalation
of dust containing arthrospores of the fungus leads to infection.
• Aspergillosis:
It is an opportunistic disease of human. Causative agent is Aspergillus
fumigatus. Infection occurs through inhalation of spores.

19. Air Borne Viral Diseases:
Air borne viral diseases are of different types. They are following,
• Common Cold:
It is the most frequent of all human infections. Characteristic symptom includes
running noses. Rhinovirus is the causative agent. Droplets with nose and throat
discharges from infected persons are the source.
• Influenza:
Symptoms of influenza are nasal discharge, head ache, muscle pains, sore
throat and general weakness. Causative agents are orthomyxovirus.
• Measles:
Measles is the most common communicable human disease mainly affecting
children. Symptoms are fever, cough, and cold and red, blotchy skin rash.
Causative virus is morbillivirus. Source of infection is respiratory tract secretions
in the form of droplets.
• Mumps:
It is a communicable disease and is a common childhood disease. It is
characterized by painful swelling of parotid glands and salivary glands. Droplets
containing infected saliva are the main source.
• Adeno Viral Diseases:
Adenoviruses cause acute self-limiting respiratory and eye infections.
Adenoviruses are transmitted by airborne mode. Diseases include acute febrile
pharyngitis, acute respiratory disease and adenovirus pneumonia.

20. SOURCES OF MICROORGANISM IN AIR:
Quite a number of sources have been studied in this connection
and almost all of them have been found to be responsible for the
air micro flora. One of the most common sources of air micro flora
is the soil. Soil microorganisms when disturbed by the wind blow,
liberated into the air and remain suspended there for a long period
of time. Man made actions like digging or ploughing the soil may
also release soil borne microbes into the air. Similarly
microorganisms found in water may also be released into the air
in the form of water droplets or aerosols. Splashing of water by
wind action or tidal action may also produce droplets or aerosols.
Air currents may bring the microorganisms from plant or animal
surfaces into air. The microorganisms are discharged out in three
different forms which are grouped on the basis of their relative
size and moisture content. They are droplets, droplet nuclei and
infectious dust. It was Wells, who described the formation of
droplet nuclei. This initiated the studies on the significance of
airborne transmission.

21.  Droplet:
Droplets are usually formed by sneezing, coughing or
talking. Each consists of saliva and mucus. Droplets
may also contain hundreds of microorganisms which
may be pathogenic if discharged from diseased persons.
Pathogens will be mostly of respiratory tract origin. The
size of the droplet determines the time period during
which they can remain suspended. Most droplets are
relatively large, and they tend to settle rapidly in still air.
When inhaled these droplets are trapped on the moist
surfaces of the respiratory tract. Thus, the droplets
containing pathogenic microorganisms may be a source
of infectious disease.

22. • Droplet Nuclei:
Small droplets in a warm, dry atmosphere tend to evaporate
rapidly and become droplet nuclei. Thus, the residue of solid
material left after drying up of a droplet is known as droplet nuclei.
These are small, 1-4µm, and light. They can remain suspended in
air for hours or days, traveling long distances. They may serve as
a continuing source of infection if the bacteria remain viable when
dry. Viability is determined by a set of complex factors including,
the atmospheric conditions like humidity, sunlight and
temperature, the size of the particles bearing the organisms, and
the degree of susceptibility or resistance of the particular microbial
species to the new physical environment. If inhaled droplet nuclei
tend to escape the mechanical traps of the upper respiratory tract
and enter the lungs. Thus, droplet nuclei may act as more
potential agents of infectious diseases than droplets. Small
droplets in a warm, dry atmosphere are dry before they reach the
floor and thus quickly become droplet nuclei.

23.  Infectious Dust:
Large aerosol droplets settle out rapidly from air on to various
surfaces and get dried. Nasal and throat discharges from a patient
can also contaminate surfaces and become dry. Disturbance of
this dried material by bed making, handling a handkerchief having
dried secretions or sweeping floors in the patient's room can
generate dust particles which add microorganisms to the
circulating air. Most dust particles laden with microorganisms are
relatively large and tend to settle rapidly. Droplets expelled during
coughing, sneezing, e.t.c consist of saliva and mucus, and each of
them may contain thousands of microorganisms. Occurs in a
warm, dry climate, and before they reach the floor quickly become
droplet nuclei. These are small and light, and may float about for a
relatively long period..

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25.  write short note on vertenary microbiology