Water Microbiology And Public Health Flashcards
Different freshwater habitats
Groundwater (aquifiers) and surface water (rivers, lakes and reservoirs)
Nutrient definition of freshwaters
Oligotrophic (low in nutrients)
Compare to mesotrophic (medium nutrients) and eutrophic (high in nutrients)
Microbes that live in freshwater
Allochthonous (not usually found in the habitat eg microbes from surrounding soil- gram +ve as need protection)
Autochthanous (usually found there)
Motile, aerobic gram negative rods
Mostly at surface level
Why are microbes in freshwater gram negative (tend to be)
Water body supports the microbe so doesnt need thick cell wall
A thick wall could be detrimental and hinder the microbe’s movement through the environment
Formation and features of an aquifier
Water from rain goes through soil= takes out impurities and many nutrients (filter)
Water lands on an impermeable surface eg rock
The environment around the water acts as a selection pressure on the microbes that can live in the aquifier
When contaminated, difficult to treat and takes a lot of time to get back to being drinkable
~1/3 NZ have nitrate (due to human activity)
~20% NZ have faecal matter (due to human activity)
Features of rivers for microbe inhabitance
Usually shallow and constantly moving/ flowing= oxygenated
Oligotrophic but this can vary- if good nutrients then microbes there will be like soil microbes from surrounding soil (as soil has high nutrients), clean rivers with essentially no nutrients will have low microbial numbers
Microbes attach to surfaces such as rocks in rivers (making slippery) so they get nutrients from the water flowing over the top of them
7 variables for grading rivers
Turbidity
Dissolved oxygen
Total phosphorus
Total nitrogen
Nitrate/ nitrite ratio
Dissolved phosphorus
E.coli levels
Where does river pollution come from
Natural- native bush debris and leaves
Agricultural- use of the nearby land, use pesticides and fertilizers= high N
Industrial- need consent to dump into a river
Urban- storm waters= microbes, rubbish and oil
Three things a lake needs to become stratified
Be in a temperate zone (arctic to tropic of cancer and tropic of capricorn to antarctica)
Occur in summer- sun warms top layer which is less dense and light winds dont disrupt this
Greater than 10m depth
What happens in a stratified lake
Top= epilimnion which is warm from the sun and contains oxygenic photosynthetic bacteria
Zone of transition= metalimnion which contains anoxygenic photosynthetic bacteris from the angle the sun hits, gets this deep for photosynthesis- zone of rapid change for O2 and temp
Bottom= hypolimnion which is cold and has microbes which perform anaerobic fermentation, sulphate reduction and methanogenesis= methane released and exits top out bubbles and H2S also released which stays at the bottom
Oxygen in lakes
Oxygen has low solubility in water (0.07%). Amount of oxygen decreased with increasing depth
Leibig’s law of the minimum
Total biomass of an organism will be determined by the nutrient present in the lowest concentration relative to the organism’s requirements (in oligotrophic waters)
Shelfords law of tolerance
There are limits to environmental factors below and above which a microorganism cannot survive and grow, regardless of the nutrient supply eg temp, pH and O2 levels
What does eutrophication lead to
Increased organic material (N and P)
Increased oxidation by decomposers
Decreased oxygen
Leads to anoxic conditions and the production of toxic products by anaerobes proliferating such as amines, hydrogen sulfate
Why is a river able to go back to normal oxygen levels when they have been depleted by eutrophication
Because it is flowing and becomes more oxygenated as it moves
Why do shallower lakes have more issue with eutrophication
They are not deep enough to absorb the increasing organic material- dont have the capacity
Deep waters are able to absorb so are therefore usually more pristine
Microbe adaptations to the aquatic environment
Small cells (ultramicrobacteria) ~0.3 micrometers- maximises surface area: vol to deal with oligotrophic conditions
Sheathed bacteria for protection and attachment to solid objects
Pigment production for protection from UV light
Motility to move towards O2 or nutrients or away from UV light with flagellum or gas vacuoles (gas cavities which give bouyancy)
Magnetotactic bacteria- magnetosomes
Utilisation of nutrients in low concentrations= increased uptake/ high affinity enzymes or changing physical appearance eg stalk to act as anchor and increase surface area
Features of magnetosomes
Membranous vesicles containing chains of iron oxide magnetite particles which respond to geomagnetic fields in the Earth
Bacteria in N hemisphere swim northward and downward
Bacteria in S hemisphere swim southward and downward
Function is to move microbes towards sediments, towards areas of optimal oxygen concentration
Stratification in oceans
Can occur but is impacted by depth and currents
Depth and surrounding NZ oceans and fishing
Two shallow regions (~200m) are the chatham rise and the Campbell clatou. Most of our fishing is done in these regions because more shallow waters will have more microbes and therefore, more fish
Oxygen concentration in the ocean
Oxygen concentration is low (0.007%) which is impacted by temperature and atmospheric pressure
Salt concentration in the ocean
Salt concentration is 3.2-3.8%, mostly NaCl, sometimes MgCl and CaCl
Hydrostatic pressure in the ocean
Hydrostatic pressure, 1000m= 100ap (increases going down)
Increases 1atm every 10m deep
Sunlight penetration in the ocean
Sunlight penetration, sufficient for photosynthesis depends on season (angle of sun), latitude (angle of sun) and turbidity (up to 50m in turbid waters). Can get up to 1000m deep
How much of the ocean is more than 1000m deep
3/4
Temperature in the ocean
Waters <200m temp varies based on global location and depth
Freezing point of ocean water is -2 to -3 deg
Ocean ranges 5 to -1.5 deg
pH of the ocean
8.3 to 8.5= alkaline
Nutrients in the ocean
Oligotrophic, containing trace elements- some sulphur but most is from photosynthetic organisms
Features of the ocean meaning that microbes decrease with depth
Hydrostatic pressure increases with depth
Sunlight penetration decreases with depth
Temperature decreases with depth
Nutrients decreases with depth
Three adaptations in microbes making them suited to the ocean environment
Halotolerant or halophilic
Piezotolerant or piezophilic
Mutualistic relationships for low nutrients
Halotolerant or halophilic for ocean microbes to deal with salt concentrations
Halotolerant= need 2.5-4% salt in the environment, they can change their active transport and how they concentrate ions in a cell depending on the salt concentration (found in estuaries)
Halophilic= require Na for high maintenance of intracellular potassium concentrations (found in pure ocean environments)
What is a saltwater wedge
Changes with freshwater constantly coming in and out at estauries
Saltwater is more dense so is found below freshwater at these wedges= microbes here are halotolerant and need to change and adapt to the changing salt concentrations
Piezotolerant or piezophilic microbes for dealing with ocean pressure
<3000m deep (300atm)= piezotolerant microbes
>3000m deep (300atm)= piezophilic microbes
Pressure affects the cellular physiology- enzymes fold differently for protection and there are also some outer membrane adaptations
Three examples of mutalism for microbes int he ocean dealing with low nutrients
Tubeworms
Luminescent bacteria
Shipworms
How does the tubeworm mutualistic relationship work
Tubeworms live by hydrothermal vents- absorb hydrogen sulfide from them
Also absorb oxygen and CO2 from the seawater
Goes to the trophosome where bacteria (primary producers, chemolithotrophic) are where they perform sulfide oxidation, making ATP used in the calvin cycle to make organic carbon for the tubeworm and the microbe
Bacteria gets salfe environment, protection and gases for nutrients
Tubeworm gets nourishment from the bacteria
