北京大学：《微生物学》课程PPT教学课件（英文版）Microbial-20Ecology

Chapter 17 Microbial Ecology Microbial Ecology: Microorganisms in soil, water, and other environments and how microorganisms act to chemically change their environments. Microbial ecologists study the biodiversity of microorganisms in nature and how different guilds interact in microbial communities. The activities of microorganisms in nature and monitor their effects on ecosystems

Chapter 17 Microbial Ecology Microbial Ecology: Microorganisms in soil, water, and other environments and how microorganisms act to chemically change their environments. Microbial ecologists study: the biodiversity of microorganisms in nature and how different guilds interact in microbial communities; The activities of microorganisms in nature and monitor their effects on ecosystems

Microbial Ecology Microorganisms in Nature Methods in Microbial Ecology Enrichment and isolation methods Identification and Quantification: Nucleic acid Probes, Fluorescent Antibodies, and Ⅴ iable counts Measurements of Microbial Activity in Nature Stable Isotopes and Their Use in Microbial Biogeochemistry Aquatic Habitats Terrestrial Environments Deep sea microbiology Hydrothermal Vents arbon cvcle

Microbial Ecology Microorganisms in Nature Methods in Microbial Ecology Enrichment and Isolation Methods Identification and Quantification: • Nucleic acid Probes, Fluorescent Antibodies, and Viable Counts Measurements of Microbial Activity in Nature Stable Isotopes and Their Use in Microbial Biogeochemistry Aquatic Habitats Terrestrial Environments Deep Sea Microbiology Hydrothermal Vents Carbon Cycle

8→83-3→3 (a) Individual Population Microorganisms in Nature Community 2 Community 1 6 CO+6H. O Oxic zone. Photic zone- cyanobacteria and c.H.O.+60 Chemoorganotrophic algae bacteria c.H.O.+60 6CO+6H. O A microbial community Sediments Anoxic zone structure in a lake ecosystem Community 3 1. Guild 1: methanogenic bacteria(co CH) homoacetogenic bacteria(Co,--acetate) 2. Guild 2: sulfate-reducing bacteria(SO-H,S) sulfur-reducing bacteria(S H S) 3. Guild 3: denitrifying bacteria (NO ferric iron-reducing bacteria (Fe Fe) 4: Guild 4: fermentative bacteria (fermenting sugars, amino and fatty acids

Microorganisms in Nature A microbial community structure in a lake ecosystem

The microorganisms and the microenvironment 15 1 5 3 Distance o (mm 3 Contour map of 02 3 3 6 concentration in a soil particle Distance(mm)

The microorganisms and the microenvironment Contour map of O2 concentration in a soil particle

The microorganisms and the microenvironment Microhabitats on a few Grains of soil Microcolony 6 Air Water Air

The microorganisms and the microenvironment

Surface and biofilms On surfaces microbial numbers and activity are usually much greater than in free water because of adsorption effects Bacteria grown on a glass slide immersed in a small river 八 Fluorescence photomicrograph of a natural microbial t community colonizing plant roots in soil

Surface and Biofilms On surfaces microbial numbers and activity are usually much greater than in free water because of adsorption effects. Bacteria grown on a glass slide immersed in a small river Fluorescence photomicrograph of a natural microbial community colonizing plant roots in soil

Biofilm Biofilms are encased microcolonies of bacterial cells attached to a surface by way of adhesive polysaccharides excreted by the cells; Functions: trap nutrients for growth of the enclosed microbial population and help prevent detachment of cells on surfaces in flowing systems Significance. in the human body, bacterial cells within a biofilm are made unavailable for attack by the immune system; dental plaque, a typical biofilm, contains acid-producing bacteria responsible for dental caries; In industry, biofilms can slow the flow of water or oil through pipelines, accelerate the corrosion of the pipes themselves

Biofilm Biofilms are encased microcolonies of bacterial cells attached to a surface by way of adhesive polysaccharides excreted by the cells; Functions: trap nutrients for growth of the enclosed microbial population and help prevent detachment of cells on surfaces in flowing systems; Significance: in the human body, bacterial cells within a biofilm are made unavailable for attack by the immune system; dental plaque, a typical biofilm, contains acid-producing bacteria responsible for dental caries; In industry, biofilms can slow the flow of water or oil through pipelines, accelerate the corrosion of the pipes themselves

Other factors affecting microbial ecology Nutrient levels and growth rates microbial competition and cooperation

Other factors affecting microbial ecology Nutrient levels and growth rates microbial competition and cooperation

Methods in Microbial Ecology Study biodiversity: isolation, identification and quantification of microorganisms in various habitats Study microbial activity Radioisotopes Microelectrodes

Methods in Microbial Ecology Study biodiversity: isolation, identification and quantification of microorganisms in various habitats. Study microbial activity: Radioisotopes Microelectrodes

Enrichment and isolation methods Enrichment culture technique: a medium and a set of incubation conditions are used that are selective for the desired organism and are counterselective for the undesired organisms The Winogradsky column: for isolation of purple and green phototrophic bacteria and other anaerobes From enrichments to pure cultures: Steak plate and agar shake tube method

Enrichment and Isolation Methods Enrichment culture technique: a medium and a set of incubation conditions are used that are selective for the desired organism and are counterselective for the undesired organisms. The Winogradsky column: for isolation of purple and green phototrophic bacteria and other anaerobes. From enrichments to pure cultures: Steak plate and agar shake tube method