Download Spectrophotometry, Colour and Turbidity

Bacterial Diversity
 Objective
 To be able to describe the main features of bacterial
cells and to understand the different nutritional and
metabolic types.
 References
 Gray N.F.
Biology of Wastewater Treatment
 Madigan M.T., Martinko J.M., Parker J.
Brock - Biology of Microorganisms
 Stanier R.Y. General Microbiology
 Lecture Outline
 Bacterial Cell Structure
 Characteristics of Bacteria
Introduction
What are they?
 Prokaryotic organisms
 Bacteria (eubacteria), Archaea (archaebacteria)
Importance in Environmental Engineering
 Biodegradation
 Nutrient Cycling
 Pathogens in Contaminated Waters
Cell Structure
Size
 smallest living organisms, 1m.
Shape
 typically cocci or rods (bacilli), spiral, stalked,
filamentous.
 multicellular swarms (gliding myxobacteria, myxococcus)
DNA
 single strand, supercoiled, no nuclear membrane.
 Extranuclear DNA or Plasmids.
Reproduction
 Asexual = Binary fission, Conjugation via Pili.
Cell Structure
Cell Wall
 Two types, Gram Positive, Gram Negative
 Both have Peptidoglycan
 Gram Negatives also have Lipopolysaccharide (LPS)
Archaea
 similar to G+ve, have pseudopeptidoglycan
Cell Structure
Flagellum




May be present - Motile
Polar or peritricious
Driven by Proton motive Force (PMF)
Chemotaxis - tumble frequency increases.
Cytoplasm
 complex subcellular organelles usually absent.
 vesicular and lamellar structures (mesosomes) form by
invagination of cytoplasmic membrane (e.g. N-fixing,
Nitrifying, and Phototrophic bacteria).
 cytoplasmic membrane essential (maintains PMF).
 Ribosomes - Protein synthesis
 Enzymes - metabolism
 Granules (Inclusions)
 Gas Vesicles (buoyancy, e.g. cyanobacteria)
Characteristics
Extreme environments
 Barophiles, halophiles,
Temperature
 Thermophiles 55 - 65C
 Mesophiles
30 - 40C
 Psychrophiles 5 - 15C
e.g. Thermus aquaticus
e.g. Escherichia coli
e.g. Flavobacterium sp.
pH
 most environments are at pH 5 - 9.
 Neutrophiles pH6 - pH8 e.g. most
 Acidophiles
< pH2
e.g. Thiobacillus ferrooxidans
 Alkaliphiles
> pH10
e.g. Bacillus sp.
Characteristics
Oxygen Requirements




Aerobic
Microaerophilic
Facultative (aerobe)
Anaerobic (strict)
Growth Requirements - Organic substrates
 Heterotrophic (Chemoorganotrophs)
– Pseudomonas, Bacillus, Zoogloea, etc.
 Key role in Nutrient Cycling
 Biodegradation of Organic Detritus
 Soluble low molecular weight substrates e.g. acetate,
methanol, sugars.
 Polymers degraded by extracellular hydrolytic Enzymes.
Metabolism
Growth Requirements - Inorganic substrates
 Autotrophic (Chemolithotrophic, Phototrophic)
– Nitrosomonas, Nitrobacter, Methanococcus, Chlorobium, etc.




Reduced forms of sulphur H2S, S0, S2O32-, SO3Reduced forms of nitrogen NH3
Hydrogen H2
Iron Fe2+
Growth Requirements - Light




Photosynthetic (phototrophic)
light and CO2
oxygenic
blue-green (cyanobacteria)
anoxygenic
green-sulphur (Chlorobium sp.)
Metabolism
Substrate Concentration
 Bacteria have high affinity, low Ks for substrates.
 
 max S 
K S  S 
 growth rate
KS substrate affinity
[S] substrate concentration
 better competitors in low substrate environments such as
in water treatment.
Capability
 Can metabolise toxic chemicals Cyanide, THM’s, etc.
 Cell physically robust.