Water Microbiology Part I Flashcards
Photic zone
In clear water light will penetrate max depth of 300 m.
- turbidity decreases this depth
Primary producers (oxygenic photoautotrophs) like algae and cyanobacteria living in this zone
Marine environment salinity, depth and temp
Pelagic zone
Main primary producer in pelagic zone
3% salinity - requires halotolerant microbes
75% is deeper than 1000 m with extreme pressure
- temp 2-3°C constant - cryophiles
pelagic zone = open ocean, low primary productivity = oligotrophic
- some areas have upwelling of nutrients from ocean floor promoting productivity
Main primary producers: prochlorophytes like Prochlorococcus (similar to cyanobacteria phylogenetically)
Adaptations for microbes in pelagic zone
Ex.
1) Reduced size (high SA to volume ratio)
2) High affinity transport systems
Ex. Trichodesmium - filamentous cyanobacteria which can float on the surface of the ocean
- contains phycobillins and can N fix
Costal waters
Eutrophic environment due to run off from the land (agricultural run off of P and N)
- causes red tides of dinoflagellates which produce neurotoxins
Primary producers: algae and cyanobacteria
- supports higher level of zooplankton and aquatic animals
Deep sea environment
300-1000m chemoheterotrophs degrade organic matter that falls from photic zones
- temp: 2-3°C (psychrophilic)
Below 1000m carbon is scarce - oligotrophic environs
Hydrothermal vents
Provide heat, source of e-, and e- acceptors
Community in hydrothermal vents:
Ex.Tube worms which do symbiosis with sulfur oxidizing chemoautotrophs
- worms trap and transport nutrients to bacterial symbionts
Fresh water environments
Highly variable in terms of nutrient availability and aeration
Oligotrophic lakes: N + P limiting nutrients, [O2] is high bc dissolution is faster than consumption
Eutrophic lakes: High primary production with algal blooms, rapid chemoheterotroph growth and rapid depletion of O2
- poor light penetration: anaerobic photosynthesis H2S –> sulfate
- health risks: pathogens, blooms –> toxins
Lakes are usually poorly oxygenated/mixed
Rivers are more mixed and oxygenated
- generally no fermentation unless there is dumping into river causing anaerobiosis
Layers of eutrophic lakes
Bottom layer: anaerobic, high in organic dead matter
- supports denitrifiers, methanogens and sulfate reducers (from anaerobic photosynthesis)
- gives bad odor
- H2S + lack of O2 can kill fish and other aerobes
Stratification occurs during summer (and winter) due to thermocline (change):
- epilimnion - less dense, aerobic layer
- hypolimnion - colder, denser anaerobic layer underneath
Spring/fall mixing of water column
BOD
Biochemical Oxygen Demand = measure of how much pollution is in a body of water (measure of oxygen consumption)
Higher BOD –> more anaerobic, chemoheterotroph consume organic material
- more fermentation, sulfate/nitrate reduction as a result of low [O2]
Dumping of sewage into water ways causes eutrophication
Biofilms
Biofilm = microbial cells embedded in ECM (protein, polysaccharides, DNA)
1) Attachment 2) Colonization + CHO prod 3) Growth 4) Active dispersal (when nutrients ↓)
Creates resistance to stress compared to planktonic (free-living) cells
Found in water systems, wet surfaces, medical devices
Waterborn bacteria and viruses to know
Salmonella typhi - typhoid fever in humans, healthy carriers –> systemic infection
Vibrio cholerae - cholera –> severe diarrhea due to enterotoxin
Shigella - bacterial dysentery (bloody diarrhea)
Salmonella - gastroenteritis
Campylobacter - gastroenteritis (most common in Canada)
Enteroviruses: poliovirus, norovirus (highly transmissible, very common), rotavirus (children)
Hepatitis A virus - vaccines available
Waterborne pathogenic protozoa to know
Prevention challenges
Entamoeba histolytica - amoebic dysentery
Giardia lamblia - backpacker’s disease (associated with drinking water in wilderness), chronic diarrhea
Cryptosporidium parvum - chronic/acute diarrhea, problem in immunocompromised, present in 90% sewage samples and 28% drinking water
Note: Hard to make drugs for eukaryotes since we share structures
- Giardia lamblia and C. parvum make cysts that are resistant to disinfectants including chlorine
- C. parvum cysts too small to filter out