Microorganisms in Ecosystems PDF

1.3 Microorganisms and Their Environment 1. Microorganisms exist in nature in populations of interacting assemblages called microbial communities. 2. The environment in which a microbial population lives is its habitat 3. Ecosystem refers to all living organisms plus physical and chemic...

1.3 Microorganisms and Their Environment 1. Microorganisms exist in nature in populations of interacting assemblages called microbial communities. 2. The environment in which a microbial population lives is its habitat 3. Ecosystem refers to all living organisms plus physical and chemical constituents of their environment 4. Microbial ecology is the study of microbes in their natural environment Microorganisms and Their Environment 1. Diversity and abundances of microbes are controlled by resources (nutrients) and environmental conditions (e.g., temp, pH, O2) 2. The activities of microbial communities can affect the chemical and physical properties of their habitats Microorganisms and Their Environment Microbes also interact with their physical and chemical environment Ecosystems greatly influenced (if not controlled) by microbial activities Microorganisms change the chemical and physical properties of their habitats through their activities For example, removal of nutrients from the environment and the excretion of waste products © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. MICROORGANISMS IN ECOSYSTEMS 1- SOIL MICROBIOLOGY Aggregates of Soil Particles  FACTORS AFFECTING MICROBIAL GROWTH IN THE SOIL (Soil as an environment for microorganisms). A combination of many physical, chemical and biological factors makes it possible for microorganisms to survive in the soil. Among these factors are: 1.Soil components (soil type and structure) 2.Soil water/moisture content 3.Aeration (The amount of air present in the soil varies, and this often has some relationship with soil water content 4.Soil temperature 5.Soil pH 6.Soil profile (Microbial populations in the soil decreases with an increase in soil depth) SOIL MICROBIOLOGY The soil (as an ecosystem) is the natural medium for terrestrial plant growth. Terrestrial Microbial Habitats: Microbes live in/on soil. Only 1% 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 primarily 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, oxygen, pH, moisture and temperature all affect the growth of microbes in the  Soil aggregate microbiology community 1- macroaggregates(0.25 to 2 mm) 2- microaggregates (