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2 Soil Microbiology

This document discusses soil microbiology and the organisms that inhabit soil. It describes the edaphon community of microorganisms in soil and the edaphic factors that influence their development, including water, pH, temperature and nutrients. It classifies soil organisms into microbiota, mesobiota and macrobiota based on their size and provides examples for each group, focusing on viruses, bacteria and fungi as the most important microorganisms in soil.

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222 views10 pages

2 Soil Microbiology

This document discusses soil microbiology and the organisms that inhabit soil. It describes the edaphon community of microorganisms in soil and the edaphic factors that influence their development, including water, pH, temperature and nutrients. It classifies soil organisms into microbiota, mesobiota and macrobiota based on their size and provides examples for each group, focusing on viruses, bacteria and fungi as the most important microorganisms in soil.

Uploaded by

T N
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Environmental Microbiology (CLS 416)

Soil Microbiology
Soil microbiology :
• Soil microbiology is the study of organisms in soil,
their functions, and how they affect soil properties.
• Soil microorganisms can be classified as bacteria,
Actinomycetes, fungi, algae, and protozoa.
 Edaphon:
The organisms living in soil create a community called
the Edaphon.
Edaphic factors

Soil is a natural living environment for various microorganisms. Their


development in soil depends on so called edaphic factors
 Water

 Osmotic pressure

 Soil's pH

 Temperature

 Oxidation

 The content of nutrients

 Toxic compounds

 Light
One % of soil is occupied by Edaphon
Soil formation factors
 Climate
 Water
 Living organisms
 Surface configuration
 Human activity and
 Time (soil's age)
Based on their size, the organisms living in soil may
be categorized into three groups:
 Microbiota (not visible with the naked eye)
viruses, bacteria, fungi, protozoa and some algae
 Mesobiota (0.2-2 mm)
nematodes (worms), mites, wingless insects,
snails, and some small plants.
 Macrobiota (>2 mm)
earthworms, larger insects, moles, rodents such
as field mice, and roots of large plants.
Viruses

 Viruses lead a strictly parasite existence - they reproduce


within bacteria, plants, animals and human cells.

 The most important kind of viruses in the soil environment


are the viruses living in bacteria cells, called bacteriophages
(phages).

 The role of phages in the soil environment depends on


their ability to eliminate some populations of bacteria.
Bacteria
Bacteria constitute the basic mass of all soil microorganisms.
They are characterized by high metabolic activity.

 Most soil bacteria are characterized by the ability to adhere


to surfaces of the mineral molecules and to the soil colloids.

 The environment that is especially suitable for the


development of the bacteria are the plants' roots and their
other underground parts.
Fungi
 Fungi belong to a group of eukaryotic organisms which are
the absolute heterotrophs.
 Most of them belong to the group of aerobes or fermenting
fungi.
 They take the carbon and energy to build their own cells
from the decomposition of the organic compounds.
 Fungi do not have any chlorophyll. In contrast to bacteria
the fungal cell wall contains chitin, glucans and other
polysaccharides.
 They occur mostly in the upper layers of soil however they
can be found as deep as 1 m.

 They get into symbiotic relationships with algae, insects and


higher plants. Many species of fungi are pathogenic to
humans, plants and animals.

 The number and composition of soil microorganisms


depends on the type of soil, its structure, humidity and on
the content of the organic matter.

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