Lecture 16: Water microbiology and public health Flashcards
(38 cards)
aquifer
normal travel of water through soil layers is halted because a impermeable substance is hit
the freshwater environment
surface water = rivers and lakes
ground water = aquifers
general habitat = low nutrients, low oxygen but can be moving (so oxygenated), lakes can be stratified
microbes found in freshwater are generally:
- oligotrophic (compare with mesotrophic and eutrophic)
- motile, aerobic, gram-negative rods
- examples are Pseudomonas, Vibrio, Flavobacterium
- microbes found in sediments are more like soil microbes
- allochthonous microbes enter the water from another habitat ; for autochthonous microbes, water is their natural habitat
why are freshwater microbes usually gram negative
because the don’t need thicker gram negative walls for protection, thicker cell wall can impede their movement
what is the gram reaction of soil microbes
–> gram positive
- because they need the protection from the thick cell wall, from soil to water nutrients has dropped and cell wall might be a problem in the water environment
allochthonous
soil is their natural environment and they flow into the water
autochthonous
they are in their natural environment eg: water is their natural environment and thats where they are
oligotrophic
low nutrients
mesotrophic
medium lvls of nutrients
eutrophic
very high amounts of nutrients, sometimes to much = causes problems
stratified
layers of temps, results from summer sun heating up the top layer of water
the marine environment
- can be stratified (but currents disturb stratification)
- low oxygen
- 3.2%-3.8% salt
pressure (1 atm increase per 10m depth) - sunlight intensity varies depending on season, latitude and turbidity
- generally low temp
- oligotrophic
summary aquatic environments
- nutrient conc. decreases with depth
- temp decreases with depth
- oxygen decreases with depth
- pressure increases with depth
- sunlight decreases with depth
–> overall microbial activity decreases with depth
–> especially decrease when the depth is greater than 1000m
–> to overcome this they need adaptations
microbial adaptations to the aquatic environment
- small cells (ultramicrobacteria)
- sheathed bacteria
- pigment production
- motility
- flagella
- gas vacuoles - magnetotactic bacteria (Fe3O4)
- utilisation of nutrients in low concentrations
- high affinity enzymes
- stalk
what is the advantage of having small cells
higher surface area to ratio = maximise nutrient uptake = essential for oligotrophic environment
what is the advantage of having sheathed bacteria
Sheath = protective, as well as helping them attach, don’t want to be at the mercy of currents
what is the advantage of pigment production
Pigment production = aquatic environment has a lot of uv exposure, pigment means they are protecting themselves against these rays
what is the advantage of motility
helping them move around aquatic environment, helps them find more nutrients (especially useful bc environment lacks nutrients)
what is the advantage of magneto tactic bacteria
Permanent magnetic dipole, enables them to respond to geomagnetic poles of the earth, anaerobes so they want to be in the sediments of the marine environment, use poles to align themselves in the sediments which is where they want to be
what is the advantage of utilisation of nutrients in low concentrations
High affinity enzymes = concentrate dilute nutrients in the environment
Stalk = outgrowths from the cell, increasing surface area of the bacteria, also help them stick to surfaces for attachment
contamination of source water: natural pollution
- salts and minerals
- makeup of the soil that the water runs across - animal or plant waste
- decaying plants, animal manure - dissolved gases
- if environment has a lot of CO2 there will be lots of carbonate in the water etc - run off from peat bogs, silt
- acidic can make the water smell, change pH and colour - natural radioactivity, heavy metals
- soil that the water catchment is collected from
contamination of source water: human pollution
- thermal
- discharge of warm water from power stations - pathogenic microorganisms
- dont want humans to have access to the area where we are collecting water from - organic matter from industries
- also good to have no industries in that area where we are collecting water from - toxic compounds
- pesticides and herbicides, enter from agriculture - eutrophication
- excess nutrient enrichment eg: algae will grow and we might end up with a algae bloom = too much nutrients can be a problem - detergents
- contain phosphate = reduces atmospheric oxygen - radioactivtiy
water treatment systems
- protection of source water
- sedimentation or screening
- aeration
- chemical flocculation
- filtration
- chlorination
- fluoridation
- ultra violet light treatment
protection of source water
- want to avoid all natural and human pollution
- come from highest source possible, no humans, no animals, no land fills
