Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Title: Environmental Microbiology 3: Microbes as a Component of Terrestrial Environments
Description: These notes cover the microbes present in terrestrial environments as well as the factors that effect the soils and the microbes that inhabit them. These notes were taken from class lectures of a year three course.
Description: These notes cover the microbes present in terrestrial environments as well as the factors that effect the soils and the microbes that inhabit them. These notes were taken from class lectures of a year three course.
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
Unit 2 Part 2 - Microbes as a
Component of Terrestrial Environments
Terrestrial Environments
Among all the microbial environments, terrestrial environments are one of the richest
and most complex
Soil constitutes the major habitat of terrestrial microorganisms and is very favorable for
growth and activities of microbes
All soils contain rich diversity of active microorganisms
Various Zones of Soil
1
...
Unsaturated or Vadose Zone
3
...
002
Silt
0
...
02
Fine Sand
0
...
20
Course sand
0
...
0
Stones & Gravel
Above 2
...
Live biomass including animals, microbes, and plant roots
2
...
Humic substances (heterogeneous matter formed by decaying and degradation
of plants, animals and microbial masses)
Organic matter
...
Organic matter
2
...
chlorides, and organic salts of Ca, Mg, Na, K
More Terminology
Eutrophic: Soil with more or less with optimum concentration of various nutrients salts
Oligotrophic: soil with sub-optimal concentration of nutrient salts
Soil acidity: associated with H-ions on exchange complex
- Expressed in pH
Effect of pH on Microbial Activity
Soil pH strongly affects the microbial activities
Below ph 5
...
root-rot of cotton, potato scab
Other soil-borne diseases are controlled by increasing pH
ex
...
H, O, CO2, N2, and others
Waterlogged soils are anaerobic, less O2
Dry soils rarely has CO2 contents (0
...
Parent material
2
...
Time
4
...
Organisms
Soil Profile: During soil formation, distinct layers or horizons are formed
Soil Layers or Horizons
Soil layer or Horizon: a layer which is approximately parallel to soil surface and that
has properties produced by soil forming processes, but are unlike those adjoining layers
Microbes present in surface soil:
-Actinomycetes
-Bacteria
-Algae
-Fungi
-Protozoa
-Bacteriophages
10,000 species of bacteria have been identified from surface soils and the population on
average is 107 to 108 cells per g of soil
Anaerobic bacteria increase with soil depth
Actinomycetes are more important under high pH, high temperature, or water stress
Classes of Indigenous Soil Bacteria
K-selected or autochthonous: these bacteria metabolize very slowly in soil
r-Selected or Zymogenous: they are adapted to intervals of dormancy and rapid
growth
Fungi → yeast and aerobic fungi range in 105 to 106 per g of soil
Mycorrhizae are also present in 103/g soil in rhizosphere
Fungi are decomposers and play important role in nutrient cycling (humification)
Decomposition of:
-
Cellulose
-
Hemicellulose
-
Pectic Substances
-
Lignin
Decomposing Fungi
Substances
Fungi which decompose
Cellulose
Aspergillus
Penicillium
Chaetomium
Trichoderma
Fusarium
Hemicellulose
Alternaria
Aspergillus
Fusarium
Trichoderma
Substances Decomposed by Fungi
Pectic Substances
-
Hydrolytic enzymes
-
Pectinases
Aerobic Bacteria Involved in Decomposing
1
...
Bacilli
3
...
Soil formation
2
...
Bioremediation
4
...
fungi and algae
Microbes secrete polysaccharides which cement soil particles
Nutrient Cycling (Decomposition of organic matter)
Dead animal and plant material is decomposed and is converted into available micro
and macro nutrients
CO2 is consumed during photosynthesis and O2 is released
Biodegradation of waste material
Bioremediation
Bioremediation: Degradation of organic pollutants into usable forms
Examples
-
Insecticides
-
Industrial chemicals
-
Petroleum products
-
Municipal waste material
-
Plastic wastes
Microbial Status in Vadose Zone
Vadose zone: the unsaturated oligotrophic environment lying between the surface and
soil and saturated zone
This zone contains less organic matter (less than 0
Title: Environmental Microbiology 3: Microbes as a Component of Terrestrial Environments
Description: These notes cover the microbes present in terrestrial environments as well as the factors that effect the soils and the microbes that inhabit them. These notes were taken from class lectures of a year three course.
Description: These notes cover the microbes present in terrestrial environments as well as the factors that effect the soils and the microbes that inhabit them. These notes were taken from class lectures of a year three course.