Transcript Groups of Organisms and their Interactions

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.
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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
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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
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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
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Prokaryotic hetertrophs and chemolithotrophs
motile and non-motile, coccoid, rod and filamentous
small, typically 1mm diameter
decomposers
 Fungi
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Eukaryotic heterotrophs
non-motile, filamentous
typically 1mm to 10mm diameter and up to 1000mm long
decomposers, predatory (nematodes)
 Algae
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Eukaryotic phototrophs
motile and non-motile, unicellular, multicellular, filamentous, branched, complex
extremely wide range mm to metres.
producers, decomposers
Classification of Organisms
 Protozoa
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Eukaryotic heterotrophs
typically motile (nonmotile retain flagella / cilia for feeding)
many shapes, some polymorphic
range 1mm to 2000mm
predatory, some phototrophic
 Metazoa -Eukaryotic heterotrophs
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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