microbial ecology n.
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Microbial Ecology

Microbial Ecology

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Microbial Ecology

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  1. Microbial Ecology Presented by: FARASAT ALI NOMAN RASHID

  2. Definitionthe interactions of m.o. with the biotic and abiotic components of the environment

  3. The importance of these interactions and their effects on the environment • Biogeochemical Cycles : describe the movement of chemical elements through the biological and geologicalcomponent of the world

  4. producers consumers The role of microorganisms ? decomposers Help in - the decomposition of pollutants and toxic wastes - the efficient utilization of limited natural resources - transformations of chemical substances that can be used by other organisms

  5. Carbon Cycle Anaerobic respiration and fermentation Org.cpd. CO2 fixation (phototrophic bacteria) (anaerobic m.o.) Methanogenic procaryotes Anaerobic CO2 CH4 CO2 Aerobic Methane-oxidizing procaryotes CO2 fixation Respiration (cyanobacteria, algae, plants, and chemoautotrophic procaryotes) (animals, plants, and m.o.) Org.cpd.

  6. Nitrogen Cycle N2O Denitrification N2 (Pseudomonas) Nitrogen fixation NO2- (Klebsiella) Anaerobic Assimilation Organic nitrogen NH3 Aerobic Assimilation Ammonification Nitrogen fixation NO3- (Rhizobium) N2 Nitrification (Nitrococcus) NO2- (Nitrosococcus)

  7. Phosphorus Cycle phytoplankton Higher plant bacteria zooplankton Dissolved org.ortho-P Precipitated inorg.-P Dissolved org.-P Sediment

  8. Sulfur Cycle Beggiatoa Thiothrix Thiobacillus sulfate assimilation R-SH So (some procaryotes) sulfate assimilation desulfurylation Aerobic R-SH H2S SO42- R-SH Anaerobic Dissimilatory sulfate reduction Chromatium Chlorobium Chromatium Chlorobium Desulfovibrio S2O32- So

  9. Photoautotrophs • Use light as E-source for CO2 fixation • Photosynthetic bacteria fix CO2 • Discovered in 1966 in Chlorobiumthiosulfatophilum • requires ATP, NADH + H+, reduced flavin, & reduced ferredoxin • ferredoxin is reduced in a light-dependent reaction coupled with the oxidation of H2S • this cycle probably occurs as a sole pathway • for CO2 fixation or in association with the • Calvin cycle • photoheterotrophs use light as an E-source & organic compound as C-source e.g.Rhodospirillaceae

  10. Chemoautotrophs Use chemical compounds (NH3, NO2-, CH4, H2S, H2) as E-source for CO2 fixation are widely distributed in the natural environment e.g. freshwater ponds and springs Nitrifying bacteria soil Sulfur-oxidizing bacteria (Thiobacillus thiooxidans Thiobacillus ferrooxidans) acid drainage water

  11. Heterotrophic CO2 fixation is a important way for m.o. to synthesize intermediates of TCA cycle from other chemical compounds Phosphoenolpyruvate + CO2 oxaloacetate + Pi ATP + pyruvate + CO2 oxaloacetate + ADP + Pi Oxaloacetate formed by either type of mechanism is used to keep the TCA cycle functioning

  12. Methanogens (Methanobacterium, Methanococcus) can anaerobically reduce CO2 to CH4 CO2 + 4H2 CH4 + 2H2O found in anaerobic habitats rich in organic matter e.g. swamps, marine sediments, intestinal tract and rumens of animals) the amount of CO2 fixed by heterotrophs and methanogens is quite small as compare to photoautotrophs

  13. soil consists of organic and mineral matter and capable of supporting life soil characteristics depend on 1. Climate and availability of water 2. Geologic age (young-old) 3. Biological inhabitants Microbes and Soil

  14. many kinds of bacteria, fungi, algae, and • protozoa are found in soil

  15. they are responsible for many of the biochemical changes in soil the most common soil bacteria : Arthrobacter, Bacillus, Pseudomonas, Agrobacterium, Alcaligenes, Flavobacterium, Streptomyces, andNocardia (Actinomyces) Bacteria are the dominant m.o. in soil

  16. anaerobes such as Clostridium and • Desulfovibrio are also found in soil • soil bacteria are especially noted for their • diverse metabolisms because the organic • nutrients in soil vary Pseudomonas Different types of CHO Bacillus Starch, cellulose, gelatin Arthrobacter Pesticides, caffeine, phenol

  17. Fungi • account for a large part of microbial population in well-aerated, cultivated soil • make up a significant part of total biomass because of their large size and extensive network of filaments • most common fungi isolated from soil : • Penicillium and Aspergillus

  18. Role and activity of fungi • degrade organic matters • control growth of other organisms e.g. • Predator protozoa, nematode • humus formation • improve soil aggregation • help in the nutrient adsorption • of plant roote.g. mycorrhiza • cause disease in human, plants, and animals

  19. Algae eucaryotic algae and cyanobacteria are found in the upper layers of soil algae do not require a source of organic carbon because …????… light accessibility, N, and P are the limiting factor in the distribution of algae

  20. Role and activity of algae increase organic carbon in soil CO2 org.-C soil corrosion (from respiration product) CO2 + H2O H2CO3 prevent soil erosion and improve soil aggregation nitrogen fixation blue-green algae

  21. are found in greatest abundance near the soil surface (104 -105 cells) why ? Protozoa adequate food supply water availability and organic matter • flagellated protozoa (e.g. Allantion, Bodo) • dominate the flora of terrestrial habitats • soil can also be a reservoir for pathogenic • protozoa such as Entamoeba histolytica

  22. Virus • different types of viruses persist in soil • - Bacteriophages of soil bacteria • - viruses that cause human, animal, and • plant dieases e.g. hepatitis virus, tobacco • mosaic virus • - are of agricultural and public health • importance • - the detection and monitoring of such • viruses in soil is important

  23. Symbiotic Nitrogen Fixation rhizosphere = the region of soil closely surrounding the roots rhizosphere effect = a consequence of the excretion of organic matter by plant roots to attract and stimulate the growth of soil bacteria an estimated 5-10 times more nitrogen is fixed symbiotically than nonsymbiotically in free-living bacteria

  24. the mutualistic association between rhizobia and legumes is highly specific The plant benefits from the bacterial conversion of gaseous N into a usable combined form the plant provides the bacterium with nutrient for growth and metabolism N-fixation occurs only if a legume is infected by a specific rhizobial species the roots of leguminous plant secrete flavonoid compounds that attract rhizobia to rhizosphere

  25. Mycorrhiza certain types of soil fungi are closely associated with the roots of vascular plants

  26. they significantly increase the absorption area of the roots for minerals and water Mycorrhizae are especially important in nutrient-poor and water-limited environments the fungus benefits from the carbohydrates made available to it by plant the plants benefit from the increased absorption area provided by the fungus

  27. Endomycorrhiza • the more common type and occur in approx. • 80% of all vascular plant • the fungal hyphae penetrate the cortical • cells of the plant root and extend into the • surrounding soil

  28. Ectomycorrhiza • are typically found in trees and shrubs, • particularly in temperate forests • the plant roots are surrounded but not • penetrated by fungal hyphae

  29. Microbial Leaching Leaching: is commercially used for the extraction of Cu, Pb, Zn, and Ur from sulfide-containing ores Thiobacillus thiooxidans and Thiobacillus ferrooxidans are acidophilic and generally found in acid environments e.g. hot springs and sulfide ore deposits they obtain carbon from CO2 and energy for growth from the oxidation of either iron or sulfur

  30. Fe2+ Fe3+ So S2- S2O32- SO42- Acid mine drainage serious problem FeS2 + H2SO4 + 1/2 O2 FeSO4 + 2 So + H2O 2 So + 2 H2O + 3 O2 2 H2SO4 Acidification of water and surrounding soil

  31. Benefit: Microbial leaching in Copper mining • low grade Cu ores contain <0.5% Cu in the • form of chalcocite (Cu2S) or covellite (CuS) T. ferrooxidans 8 Fe2+ + 2 O2 +8 H+ 8 Fe3+ + 4 H2O CuS + 8 Fe3+ + 4 H2O Cu2++ 8 Fe2++ SO42-+ 8 H+ • microbial leaching of low-grade copper ores • is important in the mining industry

  32. Microbes and the Air Microorganisms are not found in the upper regions of the atmosphere because of the temp. extremes, available oxygen, absence of nutrients and moisture, and low atmospheric pressures m.o. are frequently found in the lower portion of the troposphere (8-12 km from earth) most of them are either spore formers or microbes that are easily dispersed in the air

  33. Ex. : Cladosporium, Alternaria, Penicillium, Actinomyces, Aspergillus, Bacillus, Sarcina, Corynebacterium, Achromobacter the relative low humidity in the atmosphere and UV rays from the sun limit the types and number of m.o. in the air Nevertheless, the atmosphere serves as an important medium for dispersing many types of microbes to new environment many microbial diseases are transmitted through the air during sneezing, coughing, or even normal breathing

  34. sO mANY kINDS oF tHANKS