Chapter 10 Microbial Ecology 10.1 Microorganisms in nature - PowerPoint PPT Presentation

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Chapter 10 Microbial Ecology 10.1 Microorganisms in nature

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Chapter 10 Microbial Ecology 10.1 Microorganisms in nature ecosystem 10.2 Microbial population interactions 10.3 Biogeochemical cycles 10.4 Plant-microbe interactions – PowerPoint PPT presentation

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Title: Chapter 10 Microbial Ecology 10.1 Microorganisms in nature


1
Chapter 10 Microbial Ecology
10.1 Microorganisms in nature ecosystem
10.2 Microbial population interactions
10.3 Biogeochemical cycles
10.4 Plant-microbe interactions
10.5 Bioremediation
2
10.1 Microorganisms in nature ecosystem
1. Microorganisms and microenvironment 2.
Terrestrial Environments 3. Freshwater
Environments 4. Marine Environments
3
10.1.1 Microorganisms and microenvironment
In a microbial ecosystem individual cells grow
to form populations.
Metabolically related populations constitute
groupings called guilds.
Sets of guilds conducting complementary
physiological processes interact to form
microbial communities.
Microbial communities then interact with
communities of macroorganisms to define the
entire ecosystem.
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Microbial number and biomass in cultivated
field soil(15 cm)
6
Main types of soil microorganisms
7
Rhizosphere Effect ( R/S ratio )
The rhizosphere is the soil region in close
contact with plant roots.
Within the rhizosphere, the plant roots exert a
direct influence on the soil bacteria. This
influence is known as the rhizosphere effect.
In the rhizosphere, microbial populations reach
much higher densities in the rhizosphere than in
the free soil.
8
Microbial populations in the rhizosphere may
benefit the plant by
(1) removing hydrogen sulfide, which is toxic to
the plant roots (2) increasing solubilization of
mineral nutrients needed by the plant for growth
(3) synthesizing vitamins, amino acids, auxins,
gibberellins that stimulate plant growth (4)
antagonizing potential plant pathogens through
competition and the production of antibiotics
9
10.2 Microbial population interactions
1, neutralism (???? ) 2, commensalism (????
) 3, synergism (???? ) 4, mutualism (????
) 5, competition (???? ) 6, antagonism (?
??? ) 7, parasitism (???? ) 8, predation
(???? )
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Neutralism, there is no any physiological effect
between the populations.
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Commensalism is a unidirectional relationship
between populations in which one population
benefits and the other one is unaffected.
12
Synergism indicates that both populations benefit
from the relationship but the association is not
obligatory. Both populations are capable of
surviving independently.
13
  • Mutualism
  • Symbiosis is an obligatory interrelationship
  • between two populations that benefits both of
  • them.
  • For example
  • Protozoan-termite relationship
  • Lichens fungus and green algae
  • Rumen ecosystem

14
Competition occurs when two populations are
striving for the same resource of nutrients or
the habitat.
15
Antagonism occurs when one population produces a
substrate inhibitory to another population.
16
Parasitism, the parasite population is benefited
and the host population is harmed.
17
Predation is a widespread phenomenon where the
predator engulfs or attacks the prey. The prey
can be larger or smaller than the prey, and this
normal results in the death of the prey.
18
Classification of population interaction
  • 0, No effect , positive effect -, negative
    effect.

19
10.3 Biogeochemical cycles
1. Carbon cycle 2. Nitrogen cycle 3. Sulfur
cycle 4. Iron cycle
20
Carbon cycle
21
Carbon dioxide is incorporated, or fixed, into
organic compounds by such photoautotrophs as
cyanobacteria, green plants, algae, and green and
purple sulfur bacteria.
Chemoheterotrophs consume the organic compounds,
animals eat photoautotrophs, especially green
plants, and may in turn be eaten by other
animals.
When the organisms die, the organic compounds of
their bodies are deposited in the soil and are
decomposed by microorganisms, principally by
bacteria and fungi. During this decomposition,
carbon dioxide is returned to the atmosphere.
22
Nitrogen cycle
23
Proteins from dead cells and waste products
Microbial decomposition
Amino acids
Almost all the nitrogen in the soil exists in
organic molecules, primarily in proteins. When
an organism dies, the process of microbial
decomposition results in the hydrolytic breakdown
of proteins into amino acids.
Amino acids
Ammonia (NH3)
ammonification
The amino groups of amino acids are removed and
converted into ammonia (NH3). Ammonification is
brought about by numerous bacteria and fungi.
24
Nitrification involves the oxidation of the
ammonium ion to nitrate
Nitrosomonas
NH4
N02-
Ammonium ion
Nitrite ion
Nitrobacter
N02-
N03-
Nitrate ion
Nitrite ion
The genera Nitrosomonas and Nitrobacter are
autotrophic nitrifying bacteria. These organisms
obtain energy by oxidizing ammonia or nitrite.
In the first stage, Nitrosomonas oxidizes
ammonium to nitrites. In the second stage, such
organisms as Nitrobacter oxidize nitrites to
nitrates
25
Key processes and prokaryotes in the nitrogen
cycle
26
Sulfur cycle
27
Key processes and prokaryotes in the sulfur cycle
28
Iron cycles
  • Bacterial iron reduction and oxidation
  • Fe2 1/4O2 2OH-1 1/2H2O Fe(OH)3

Ferrous iron oxidation at acid pH Thiobacillus
ferrooxidans, an iron-oxidizing bacterium, is
strict acidophile, a small number of cells can be
responsible for precipitating a large amount of
iron.
29
Pyrite ???oxidationmetal bioleaching????
  • One of the most common forms of iron and sulfur
    in nature is pyrite (FeS2), in mining operation,
    a slow chemical reaction occurs
  • FeS2 31/2O2 H2O Fe2 2SO42- 2H
  • Fe2 Thiobacillus ferrooxidans Fe3
  • FeS2 14Fe3 8H2O 15Fe2 2SO42-
    16H

Spontaneous
30
Role of iron-oxidizing bacteria in the oxidation
of the mineral pyrite
31
Probiotics for humans and animals
  • Probiotics??? living microorganisms or
    substances to promote health and growth, has the
    potential to reestablish the natural balance and
    return the host to normal health and nutrition.
  • Prebiotics ???oligosaccharide??
  • Synbiotic the combination of prebiotics and
    probiotic microorganisms.

32
How Probiotic microorganisms displace pathogen
  • 1. Competition with pathogens for nutrients and
    adhesion sites
  • 2. Inactivationof pathogenic bacterial toxins or
    metabolites
  • 3. Production of substance that inhibit pathogen
    growth
  • 4. Stimulation of nonspecific immunity

33
Protential health benefits of probiotic
microorganisms for humans
  • 1. Anticarcinogenic ???activity
  • 2. Control of intestinal pathogens
  • 3. Improvement of lactose use in individuals who
    have lactose intolerance
  • 4. Reduction in the serum cholesterol
    concentration

34
10.4 Plant-microbe interactions
1. Lichens and Mycorrhizas 2.The plant
environment 3. Root nodule bacteria and symbiosis
with legumes
35
Lichens
Lichens are leafy or encrusting growths that are
widespread in nature and are often found growing
on bare rocks, tree trunks, house roofs, and
surfaces of bare soils . The lichen plant
consists of a symbiosis of two organisms, a
fungus and an alga. Lichens consist of a tight
association of many fungal cells within which the
algal cells are embedded .
36
Mycorrhizas
Mycorrhiza literally means "root fungus" and
refers to the symbiotic association that exists
between plant roots and fungi. Probably the roots
of the majority of terrestrial plants are
mycorrhizal. There are two classes of
mycorrhizae ectomycorrhizae, in which fungal
cells form an extensive sheath around the outside
of the root with only little penetration into the
root tissue itself, and endomycorrhizae, in which
the fungal mycelium is embedded within the root
tissue.
37
Mycorrhizas
  • Type of Mycorrhizas Ectomycorrhiza and
    Endomycorrhiza
  • Morphology and Function of Mycorrhizal Infection
  • Mycorrhiza and Plant Nutrition
  • Application Potential of VAM in Agricultural
    practice and Ecosystem
  • Development and Application of Molecular Probes
  • Construction and Analysis of Genomic Library

38
Mycorrhizas
  • Ectomycorrhizas
  • Endomycorrhizas
  • Ectendomycorrhizas

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40
Functions of mycorrhiza
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42
Root Nodule Bacteria and Symbiosis with Legumes
  • Stages in Nodule Formation
  • Biochemistry of Nitrogen Fixation in Nodules
  • Genetics of Nodule Formation nod Genes
  • Genetic Cooperativity in the Rhizobium-legume
    Symbiosis
  • Construction and Application of
    Genetic-engineered Rhizobium

43
Symbiosis of Frankia and Non-leguminous Plant
  • Morphology and Physiological Characteristic of
    Frankia
  • Hosts
  • Application Potential

44
10.5 Bioremediation
1. Pollutants 2. Means of bioremediation
45
Wastewater treatment

Waste resource industrial?agricultural and
human Materials organic matter
46
Measuring water quality

TOCtotal organic carbon CODchemical oxygen
demand BODbiochemical oxygen demand(20 ? 5days)
47
Treatment goal
  • Removal of dissolved organic matter and
    possibly inorganic
    nutrients
  • Inactivation and removal of pathogens

48
Water Treatment processes
  • Primarycan remove 20-30 of the BOD
  • Secondary 90-95of the BOD and many bacterial
    pathogens are removed
  • Tertiaryremove nonbiodegradable organic
    material?heavy metals?and minerals

49
Activated sludge treatment

Activated sludge a recycle system of sludge
of active biomass formed with oxidized and
degraded organic matter
50
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,?????????????????????
51
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Questions
  • What is Microbial Ecology and What do microbial
    ecologists study?
  • populations,guides,communities, ecosystem
  • What is the critical characteristic of a
    mutualistic relationship?
  • What is lichen?
  • Schematically describe nitrogen and sulfur cycles
    and microorganisms involved.
  • What are prebiotics, probiotics, synbiotics? How
    do they benefit to human or animals?
  • Explain how primary secondary and tertiary
    treatment are accomplished.
  • What is activated sludge ?
  • After anaerobic digestion is completed , why is
    sludge disposal still of concern? How can it be
    further treated to improve its quality?
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