Transcript Ecology of microorganisms

Chair of Medical Biology, Microbiology,
Virology, and Immunology
MICROBIAL
ECOLOGY
Kuchmak O.B.
What is Microbial Ecology?
What is “Microbial”?
– of or referring to a minute life form; a
microorganism, especially a bacterium that
causes disease. Not in technical use.
What is “Ecology”?
– the study of the interactions between organisms
and their environment
Microbial ecology = The study of interactions between
microorganisms and their environment (chemical, physical,
and biological environment!)
In microbial ecology the main concepts are:
population - an elementary evolutional
unit (structure) of a definite species;
biotope - site, habitation of a population,
for parasites - place of their localization in
an organism;
In microbial ecology the main concepts are:
microbiocenosis - microbial association,
that is collection of populations of different
species of microorganisms, which live in
the defined biotope (for example, in an oral
cavity, skin);
ecosystem - system, in which enters a
biotope and microbiocenosis.
Symbiosis - living together of two dissimilar organisms
Types of symbioses:
Neutralism - the populations,
existing in one biotope do not stimulate
and do not oppress each other.
Mutualism exists when organisms
live in an obligatory but mutually
beneficial relationship.
The mutualistic association between
rhizobia and N-fixing bacteria
Types of symbioses:
Commensalism - such relationship, at
which the member called the commensal
receives benefits, while its coinhabitant is
neither harmed nor benefitted.
Types of symbioses:
Antagonism - oppression of one
population another. The microbes –
antagonists
produce
antibiotics,
bacteriocines, fatty acids, which cause
destruction of bacteria or delay their
reproduction.
A
B
Types of symbioses:
Parasitism - such kind of symbiosis, at which
one population (parasite) brings harm to the host,
and for itself has a benefit.
Ricketsia – intracellular parasites
• The soil is the major
environment for a habitation
of microorganisms.
• The amount of bacteria in one
gram of soil can be very great
- from 200 millions up to 10
billions
• The ground mass of bacteria
is on depth 10-20 cm.
The microflora of soil includes
hundreds of species of bacteria, viruses,
protozoa, actinomyces and fungi. It is
various species of putrefactiving,
ammonifying, nitrifying, denitrifying,
nitrogen-fixing bacteria, numerous iron
bacteria and sulphur-bacteria. The most
often inhabitants of soil are the
representatives of genus Azotobacter,
Nocardia, and Clostridium.
producers
consumers
The role of microorganisms ?
decomposers
Help in
- the decomposition of pollutants and toxic wastes
the efficient utilization of limited natural resources
transformations of chemical substances that can
be used by other organisms
General microbial number (GNM) – quantity
(amount) of all saprophytic bacteria in 1 g of soil
is examined.
More exact rating is manufactured at
definition coli - index, that is amount of
bacteria E.coli in 1 g of soil.
The soil is considered pure, if its coli-index
does not exceed 2000, and the quantity of
termophilic bacteria is in limits 100 - 1000.
Sanitary - indicative bacteria of soil
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Escherichia coli,
Streptococcus faecalis,
Clostridium perfringens
termophilic bacteria.
A degree of fecal contamination
of soil is determined on presence and
quantity(amount) of first three species.
Soil Pathogens
Clostridium botulinum,
Clostridium tetanus,
Clostridium perfringens,
Bacillus anthracis
Water is a natural medium of a
habitation of various microorganisms.
In sweet and salty waters
representatives of all groups of bacteria
are found Protozoa, Fungi, Viruses,
Water - plant.
The microflora of reservoirs consists of two
groups of microbes:
autochtonal (or aqueous) microorganisms /
permanently live and are multiplied in water/. It
is more often such species: Micrococcus
candicans, M. roseus, Sarcina lutea, Bacterium
aquatilis communis, Pseudomonas fluorescens.
The anaerobes represent by species Clostridium,
Bacillus cereus, B. mycoides.
allochtonal (brought from the outside).
The microbial composition of water is in
the large degree mirrors a soil microflora. A
major factor, which determines quantity of
microbes in water is presence in it of
necessary nutritious materials, that are
various biological matters.
Main path of microbial contamination of
water is penetration of unpurified waste from
sewage of the populated area. Therefore, the
more water is polluted with similar organic
matters, there are more in it of microorganisms.
Zones of water clearness
Polisaprogenic zone is the zone of strong
contamination. It contains many organic matters and
almost there is no oxygen. The quantity of bacteria in
1 ml of water reaches one million and more.
Mesosaprogenic zone is the zone of moderate
contamination(pollution)). In it the nitrifying and
aerobic bacteria prevails. The total number of
microorganisms compounds hundreds of thousand in
one ml.
Oligosaprogenic zone (zone of pure water). The
quantity of bacteria changes from 10 up to 1000 in
one ml.
Sometimes the pathogenic bacteria in
water can get and they will be saved for some
time: Salmonella spp., S. typhi, V. cholerae,
.S. dysentеriae, L. interrogans.
Often various viruses are found:
Polioviruses, Rotaviruses, Enteroviruses,
Hepatitis A virus and others.
The pathogenic microorganism getting in
reservoirs, abundant in a zone of strong
contamination, gradually die in a zone of
moderate contamination. They are almost not
found in oligosaprogenic zones.
Common microbial number of water is examined by
inoculation of 1 ml of water in melted and refrigerated up
to 50 C in agar in Petri dishes.
Coli-index is determined by a method of membrane
filters or fermentation tests.
Membrane filtration for
determinging the coliform
count in a water sample
using vacuum filtration.
Enzymatic assay for coliform
• Colilert system (for P-A test)
• β-galactosidase of coliform
substrate ONPG → nitrophenol (yellow)+Gal
• β-glucuronidase of E. coli
fluorogenic substrate MUG
Microflora of air
Air for microorganisms is less favorable
environment, than soil and water.
There are almost no the nutritious materials
necessary for reproduction of bacteria.
Desiccation and the ultraviolet rays operate
perniciously on microorganisms.
Nevertheless, many microbes in air can be
saved more or less long time.
Main sources of microbial air pollution is
the soil, water and man.
The composition of a microflora of air is
very various. It depends on cleanness of air,
deposits, temperature, humidity, climate and
geographical conditions. Than it is more in
air of a dust, smoke, soot, the more microorganisms.
Vice-versa, above mountains, seas, oceans
and woods, where air is pure, it is not enough
of microbes.
In open air spaces there are less of
microbes, than in the closed rooms.
The constant microflora of air is shaped
at the expense of soil microorganisms. In its
composition many species of Actinomyces,
Penicillinum, Aspergillus, Mucor and others
go into. There are many Micrococcous roseus,
M. candicans, M. luteus, Sarcina lutea, S. alba,
S. rosea, Bacillus subtilis, B. mycoides, B.
mesentericus.
Many microbial diseases are transmitted
through the air during sneezing, coughing, or
even normal breathing:
bacterial - tuberculosis, diphtheria,
legionellosis, wooping cough, acute
angine, epidemic meningitidis,
viral - influenza, measles, mumps,
adenoviral infection
A sanitary - hygienic rating of air include
 general microbial number
 sanitary - indicative microorganisms:
Streptococci haеmolyticus,
S. viridans,
Staphylococcus aureus.
Examination of air microflora is made
according to
 Koch’s sedimentation method
 Krotov’s aspiration method.