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Microbes and Metabolism

Microbes and Metabolism. AIM To gain an understanding of : The key microorganisms relevant to Water & Wastewater The different mechanisms of energy production and metabolism References Lester JN & Birkett JW (1999): Microbiology and Chemistry for Environmental Scientists and Engineers

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Microbes and Metabolism

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  1. Microbes and Metabolism AIM To gain an understanding of : • The key microorganisms relevant to Water & Wastewater • The different mechanisms of energy production and metabolism References • Lester JN & Birkett JW (1999): Microbiology and Chemistry for Environmental Scientists and Engineers • Madigan MT, Martinko JM & Parker J (2000): Brock - Biology of Microorganisms • Hawker L.E. and Linton A.H.: Microorganisms - Function, Form and Environment

  2. Why study the biology of water ? • Microbiology is Fundamental to many Wastewater Treatment processes. • Carbon oxidation • Nutrient Removal • Solids Removal • Optimisation of performance • Stability of system to perturbations • flow, influent composition • New Processes • Water Supply - Safety and Quality • Pathogens • Bacterial - Vibrio cholera,Salmonella typhi, Legionella pneumophila • Viral - Hepatitis A, Coxsackievirus A & B, Enterovirus • Protozoan - Entamoeba histolytica, Giardia lamblia • Helminths - tapeworm Taenia saginata, roundworm Ascaris • Toxins • cyanobacterial blooms

  3. Nomenclature • Biology • the study of living things • Zoology • the study of macroscopic vertebrates and invertebrates • Botany • the study of higher plants (Macrophytes) • Microbiology • the study of microorganisms • Bacteriology - (bacteria) • Mycology - (fungi) • Virology - (viruses) • Protozoology (unicellular animals) • Phycology (unicellular and multicellular algae)

  4. Some Biological Fundamentals • Cells - specialised (differentiated) • Cell Walls - Polymer Reinforcement • Membranes - impermeable barrier, • Cytoplasm - internal medium • Nucleus - DNA • Vacuoles - storage, pressure • Ribosomes - protein synthesis (translation) • Enzymes - proteins which catalyse chemical reactions • Proteins - Lipids - Carbohydrates

  5. Definition if ‘LIVING’ • Movement • usually visible, plant cells, trophism • Responsiveness • react to stimuli • Growth • increase in mass • Feeding • active uptake of new ‘building blocks’ and energy. • Respiration • metabolic release of energy • Excretion • efflux of waste products • Reproduction • new generations of similar organisms

  6. Classification of Microorganisms • Prokaryotes • DNA present as a single chromosome • Only small amounts of protein associated with the DNA • have few or no membranes within the cell • Do not have a nucear membrane • e.g. Bacteria • Eukaryotes • DNA present as multiple chromosomes • Chromosomes associates with large amounts of protein • the cytoplasm contains membranes which can be structured (organelles) • Have a nuclear membrane (DNA visible as a nucleus) • e.g. Yeasts, Fungi, all higher organisms

  7. Classification of Organisms • Bacteria • Prokaryotic hetertrophs and chemolithotrophs • motile and non-motile, coccoid, rod and filamentous • small, typically 1mm diameter • decomposers • Fungi • Eukaryotic heterotrophs • non-motile, filamentous • typically 1mm to 10mm diameter and up to 1000mm long • decomposers, predatory (nematodes) • Algae • Eukaryotic phototrophs • motile and non-motile, unicellular, multicellular, filamentous, branched, complex • extremely wide range mm to metres. • producers, decomposers

  8. Classification of Organisms • Protozoa • Eukaryotic heterotrophs • typically motile (nonmotile retain flagella / cilia for feeding) • many shapes, some polymorphic • range 1mm to 2000mm • predatory, some phototrophic • Metazoa -Eukaryotic heterotrophs • Rotifera (simple invertebrates) • Nematoda (unsegmented worms) • Annelida (segmented worms) • Insecta • Coleoptera (beetles), Diptera (flies) • Higher Organisms • Amphibia, Fish

  9. 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101 102 millimetres Molecular Biological atoms viruses bacteria algae, fungi amino acids light microscope electron microscope 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101 102 Orders of Magnitudein the Living World

  10. Metabolic Diversity • Aerobic • where the terminal electron acceptor is dioxygen (O2). Most efficient metabolism in terms of energy production. • Anaerobic • where oxidized inorganic species e.g.. NO3- and SO42- act as electron acceptors in the absence of oxygen. • obligate anaerobes, facultative anaerobes • Fermentation • metabolism of organic compounds without the requirement for external electron acceptors • energy derived from substrate-level phosphorylation • low efficiency with incomplete metabolism of substrate e.g. glucose to ethanol • Maintenance Energy • minimum requirement for staying alive • Growth Rate • rate at which cell divides • Doubling Time - Turnover Time

  11. Metabolism • Substrate Concentration • Bacteria have high affinity, low Ks for substrates.  growth rate KS substrate affinity [S] substrate concentration • better competitors in low substrate environments such as in water treatment. • Metabolic Capability • Can metabolise toxic chemicals Cyanide, THM’s, etc. • Cell physically robust.

  12. Metabolic Diversity • Assimilative • metabolic modification of a chemical species for the purpose of its incorporation into cellular components. • e.g. NO3- , SO42- , and CO2 are reduced before being incorporated into proteins and carbohydrates as (-NH2), (-SH), and (-CH2) groups. • occurs in bacteria, fungi, algae and plants • Dissimilative • metabolic modification of a chemical species in order to generate energy. • NO3- , SO42- , and CO2 are reduced to NH3 , H2S and CH4 which are then excreted from the cell. • carried out by a relatively small number of bacterial species.

  13. Metabolic Diversity • Autotroph • An organism using CO2 as its source of carbon. • Heterotroph • An organism requiring organic compounds as a carbon source. • Phototroph • An organism utilising light as the source of cell energy (e.g. algae) • Chemoorganotroph • Uses organic chemicals as energy sources (electron donor) e.g. most bacteria, all nonphototrophic eukaryotes (e.g. man). • All are Heterotrophs. • Chemolithotroph • Uses inorganic chemicals as energy sources (electron donor), as most obtain carbon from CO2 they are usually Autotrophs • Some Chemolithotrophic bacteria obtain carbon from organic compounds (chemolithotrophic heterotrophs) are termed Mixotrophs.

  14. Metabolic Diversity CARBON SOURCE Inorganic Compounds CO2 HCO3- CO32- Organic Compounds ENERGY Purple and green bacteria. Some algae. (Photoheterotrophs) Algae, Cyanobacteria and purple/green bacteria. (Photoautotrophs) Light Some sulphur bacteria. (Chemolithotrophic heterotrophs or Mixotrophs) Iron, sulphur and nitrifying bacteria. (Chemolithotrophic Autotrophs) Inorganic Cpds Most prokaryotes and eukaryotes. ( Chemoorganotrophs ) Organic Cpds Not known

  15. Microbial Ecology • Individuals • Populations • many of the same species • Guilds • metabolically related microorganisms e.g.. homoacetogenic bacteria • Communities , Consortia • mixed species, interactions between Guilds • Competition • rivalry among organisms for a common resource • Symbiosis • physical interaction between species which is positively beneficial to both e.g.. lichens, mycorrhizae, mussels • Syntrophy • cooperation between organisms e.g.. metabolite exchange

  16. Examples of Microbial Communities Producer Community photosynthetic microbes algae, cyanobacteria Heterotrophic Community Chemoorganotrophic bacteria Carbon and nutrient inputs Lake Carbon and nutrient cycling nutrients Sediment Sediment Methanogenic Community Guild A - hydrolytic bacteria Guild B - fermentative bacteria Guild C - acetogenic bacteria Guild D - methanogenic bacteria

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