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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 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 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) 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 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 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 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 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 Orders of Magnitude in the Living World 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 Molecular -1 10 0 10 1 10 1 10 2 Biological amino acids atoms 10 viruses bacteria algae, fungi light microscope 10 -9 10 -8 10 -7 10 -6 electron microscope -5 -4 -3 10 10 10 10 -2 10 -1 10 0 10 2 millimetres 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 Metabolism Substrate Concentration Bacteria have high affinity, low Ks for substrates. m growth rate KS substrate affinity [S] substrate concentration m m max S K S S better competitors in low substrate environments such as in water treatment. Metabolic Capability Can metabolise toxic chemicals Cyanide, THM’s, etc. Cell physically robust. 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. 2 NO3 , SO4 , 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. 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. Metabolic Diversity CARBON SOURCE ENERGY Organic Compounds Inorganic Compounds CO2 HCO3- CO32- Purple and green bacteria. Some algae. (Photoheterotrophs) Algae, Cyanobacteria and purple/green bacteria. (Photoautotrophs) Inorganic Cpds Some sulphur bacteria. (Chemolithotrophic heterotrophs or Mixotrophs) Iron, sulphur and nitrifying bacteria. (Chemolithotrophic Autotrophs) Organic Cpds Most prokaryotes and eukaryotes. ( Chemoorganotrophs ) Not known Light 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 Examples of Microbial Communities Producer Community photosynthetic microbes algae, cyanobacteria Carbon and nutrient inputs Heterotrophic Community Chemoorganotrophic bacteria 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