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 1m diameter decomposers

Fungi Eukaryotic heterotrophs non-motile, filamentous typically 1m to 10m diameter and up to 1000m long decomposers, predatory (nematodes)

Algae Eukaryotic phototrophs motile and non-motile, unicellular, multicellular, filamentous, branched, complex extremely wide range m to metres. producers, decomposers

Protozoa Eukaryotic heterotrophs typically motile (nonmotile retain flagella / cilia for feeding) many shapes, some polymorphic range 1m to 2000m predatory, some phototrophic

Metazoa -Eukaryotic heterotrophs Rotifera (simple invertebrates) Nematoda (unsegmented worms) Annelida (segmented worms) Insecta

– Coleoptera (beetles), Diptera (flies)

Higher Organisms Amphibia, Fish

Classification of Organisms

Orders of Magnitudein the Living World

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 aminoacids

viruses bacteria algae, fungi

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

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.

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.

SK

S

S max

Metabolic Diversity

Assimilative metabolic modification of a chemical species for the purpose of its incorporation into

cellular components.

e.g. NO3- , SO4

2- , 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- , SO4

2- , 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

Inorganic CompoundsCO2 HCO3

- CO32-

Organic CompoundsENERGY

Light

InorganicCpds

OrganicCpds

Purple and greenbacteria. Some algae.(Photoheterotrophs)

Algae, Cyanobacteria and purple/green bacteria.(Photoautotrophs)

Iron, sulphur andnitrifying bacteria.(Chemolithotrophic Autotrophs)

Some sulphur bacteria.(Chemolithotrophicheterotrophsor Mixotrophs)

Most prokaryotes and eukaryotes.( Chemoorganotrophs )

Not known

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

Sediment Methanogenic CommunityGuild A - hydrolytic bacteriaGuild B - fermentative bacteriaGuild C - acetogenic bacteriaGuild D - methanogenic bacteria

Producer Communityphotosynthetic microbesalgae, cyanobacteria

Heterotrophic CommunityChemoorganotrophic bacteria

Lake

Sediment

Carbon and nutrient inputs

Carbon and nutrient cycling

nutrients