microbiology of water

what does biological activity of aquatic ecosystems depend on

what does biological activity of aquatic ecosystems depend on

activities of primary producers

the activities and net numbers of phytoplankton depends on:

temperature

light received

availability of specific limiting nutrients such as nitrogen and phosphorous

what is the photic zone

the depth into the water that light will penetrate in clear water

300m

relevancy: microorganisms must be able to harvest the light that reaches them using accessory pigments

characteristics of marine environments

high salinity (halotolerant organisms)

below 100m the temperature is constant 2-3C

open ocean characteristics (pelagic zone)

low primary productivity due to low inorganic nutrients

oligotrophic

cool, constant temperatures

wind and ocean currents can cause upwelling to bring nutrients to the surface and promote productivity

where does most primary productivity in the open ocean happen

prochlorophytes (related to cyanobacteria) - prochlorococcus

what are adaptations seen in pelagic microorganisms

reduced size for higher S:V ratio

high affinity transport systems

what are the characteristics of coastal waters

eutrophic: productivity is higher because of the influx of nutrients from rivers and other polluted water sources

can cause red rides - nitrogen is a limiting nutrient

higher concentration of animals due to higher primary productivity

what are the primary producers in coastal waters

algae and cyanobacteria

what is the deep sea

300-1000m deep

chemoheterotrophs live off dead organic matter that falls (psychrophiles)

organic carbon is scarce, there are very few microorganisms below 1000m

what are hydrothermal vents

sources of heat, nutrients, electron donors and aceptors

generates community of microorganisms and animals

example of animal in hydrothermal vents

tube worms - symbiosis with sulfur oxidizing chemoautotrophs

trap and transport nutrients to bacterial symbionts

freshwater environment characteristics

highly variable

microbial populations depend on nutrient availability and light and oxygen availability

limited by N and P

lakes have poor mixing and aeration while rivers have good

oligotrophic lakes (N and P limited)

low primary productivity and organic matter

growth of aerobic chemoheterotrophs limited by nutrient supply

organic matter doesn’t accumulate

rate of oxygen dissolution is higher than the comsumption rate - oxygen saturated

clear water - deep light penetration

eutrophic lakes (nutrient rich)

high primary productivity and organic matter

rapid growth of chemoheterotrophs and rapid depletion of dissolved oxygen

low O2

anaerobic zones are created

poor light penetration

there’s another slide i’m overwhelmed by

how do anaerobic zones develop

due to summer stratification (temperature differences)

how does temperature stratification work

when air temperature rises, surface water is warmed forming the epilimnion which is less dense

the cold bottom layer - hypolimnion - is separated from the epilimnion by the thermocline

what is the thermocline

zone of rapid temperature change that separates the hypolimnion and the epilimnion in temperature lakes

what is mixing in lakes

happens in fall and spring when water temperature is constant in all layers

brings nutrients up the water column

mixing in rivers

good

ensures organic matter is degraded effectively

no fermentation or H2S production occurs

excess organic matter may happen in anaerobiosis which leads to similar things as eutrophic lakes

pollution of fresh water

deliberate discharge of effluents into a water way

why is sewage a pollutant

rich in organic matter

contains a large number of organisms - some may be pathogens

organic matter is oxidized using dissolved oxygen - high BOD

what happens when biochemical oxygen demand (BOD) is high due to pollution

water becomes anaerobic, microbial metabolisms increase

fermented products, sulfate reduction, nitrate reduction

what is biofilm

microbial cells embedded inside an extracellular matrix

usually produced by mixed populations of species

resistant cells

found in water systems

how do biofilms happen

attachement of a few motile cells

colonization and growth

development

active dispersal of motile cells - triggered by environmental factors

properties of biofilm (slide)

localized gradients, sorption, enzyme retention, cooperation, competition, tolerance and resistance

water borne pathogens

grow in intestinal tract and transmission is mediated by fecal contamination of water supplies

what are sources of water borne infections

potable water and recreational water (swimming)

examples of water borne pathogens (slide)

salmonella typhi, campylobacter, enterovirus

what does entamoeba histolytica cause (water born pathogenic protozoa)

amoebic dysentery

what does giardia lamblia cause (water born pathogenic protozoa)

giardiasis (beaver fever)

diarrhea

associated wtih drinking water in wilderness areas

cryptosporidium parvum (water born pathogenic protozoa)

diarrhea

no reliable treatment

cyst formation of G lambia and C parvum

form cysts that are resistant to disinfectants

c parvum cysts are not removed by plant filtreation of water

how can water be tested for quality

test for organisms that are present in large numbers in feces

indicates that the water might also contain pathogens

presence of fecal coliforms indicate contamination

absence does not guarantee water quality because of cysts

what are the two water quality indicators

coliforms and fecal coliforms

coliforms as quality indicators

can ferment lactose, are facultative aerobes

bacteria that are not all of intestinal origin

fecal coliforms as quality indicators

coliforms derived from the intestines of warm-blooded animals

thermotolerant

membrane filtration testing

drains a water sample through a filter to catch the pathogen cells which are then cultured

tests large volumes of water

detects both coliforms and fecal foliforms

faster and easier than MPN

most probable number (MPN) testing

tests for coliforms

samples are added to a lactose broth

positive when gas is produced

uses statistical tables to estimate number

requires further testing to confirm

what are the goals of water treatment

remove pathogens

improve clarity

remove compounds that taste or smell poor

soften the water

what are the steps of water treatment

1. sedimentation

2. flocculation treatment (chemical coagulation)

3. filtration

   1. disinfection

what is the sedimentation step

leaving water to stand

allows large particle to settle

what is the flocculation step

a coagulant is added

water in transferred to a flocculation basin and allowed to settle

precipitates form and trap fine particles

80% of bacteria and colour have been removed

what is the filtration stage

water is filtered through sand to remove remaining particles and cysts

most bacteria has been removed

filter is backflushed to prevent clogging

what is the disinfection step

chlorination to kill remaining organisms and neutralize stinky chemicals

residual chlorine: leftover chlorine when it leaves treatment plant intended to protect the water in the distribution system

using ozone for disinfection

more effective than chlorine because it can kill cysts however it has a very short half life

wastewater/sewage treatment aims

reduce BOD and removes organic matter

destroys pathogens

requires a primary and secondary and tertiary treatment

primary treatment

sedimentation tanks and flocculation

produces primary sludge

reduces BOD

can be discharged into waterways or to secondary treatment

secondary treatment (liquid stage)

trickling filter: liquid from primary treatment is sprayed over rock so that microorganisms form a biofilm and oxidize organic matter - reduces BOD

activated sludge: air is blown through the liquid, slime forming bactera clump and form activated sludge to oxidize OM. sludge is removed for disposal - reduces BOD

secondary treatment (sludge)

sludge is microbially digested under anaerobic conditions

CH4 produced can power the plant

BOD is reduced

remaining material is burned

tertiary treatment - liquid

reduced BOD, bacteria and N and P

can be biological treatment, flocculation, filtration, chlorination

final liquid effluent may be suitable for drinking

septic tank

minimal treatment

inside the tank the material settles and minimal sludge digestion happens

effluent flows to a leaching field so the soil can filter and decompose organic matter

cannot contaminate groundwater or waterways because it is disgusting!