Microbes and Metabolism

1. Microbes and Metabolism AIM To gain an understanding of the following: • The Key Microorganisms in Environmental Engineering • The different mechanisms of energy production and metabolism References • Kiely G (1996): Environmental Engineering • 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 Water Microbiology ? • 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 invertebrate • 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. Classification of Organisms • 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

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

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

7. Some Biological Fundamentals • 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

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

9. Microbial Interactions • Ecosystem • stable association of biological, physical, and chemical components • Environment • everything surrounding a living organism • Microenvironment • the immediate environmental surroundings • Habitat • location in nature where an organism resides • Niche • specific conditions of pH, light, water, temperature etc within a habitat which favour a particular organism

10. Microbial Ecology • Individuals • single cell • Populations • many individuals 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 • an interaction between species which is positively beneficial to both e.g.. lichens, mycorrhizae, mussels • Syntrophy • cooperation between organisms e.g.. metabolite exchange

11. Microbial Communities Light Producer Community photosynthetic microbes algae, cyanobacteria Lake Nutrient cycling Decomposer Community Chemoorganotrophic bacteria Sediment Sediment Community (decomposers) Guild A - fermentative bacteria Guild B - methanogenic bacteria Guild C - sulphate reducing bacteria Guild D - Denitrifying bacteria

12. Metabolic Diversity • Aerobic • dioxygen (O2) is terminal electron acceptor.Most efficient type of metabolism • Anoxic • oxidized inorganic species e.g.. NO3- and SO42- act as electron acceptors (NO oxygen) • Anaerobic • Carbon dioxide is terminal electron acceptor • 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

13. 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 few number of bacterial species.

14. Metabolic Diversity • Autotroph • An organism using CO2 as its carbon source. • 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) • most obtain carbon from CO2 i.e. are Autotrophs • Some obtain carbon from organic compounds (are chemolithotrophic heterotrophs) also known as Mixotrophs.

15. 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 Inorganic Cpds Some sulphur bacteria. (Chemolithotrophic heterotrophs or Mixotrophs) Iron, sulphur and nitrifying bacteria. (Chemolithotrophic Autotrophs) Most prokaryotes and eukaryotes. ( Chemoorganotrophs ) Organic Cpds Not known