Lecture 6 Whyte Flashcards
Industrial activities produce many contaminants that are unfortunately harmful to the environment and _________
human health
What did the Lancet Report revealed in 2017:
Pollution is causing more deaths worldwide than war or smoking - 1/6 deaths are now caused by pollution!
What is the fate of such contaminants when they are released into the environment:
- water pollution
- groundwater pollution
- soil/sediment pollution
The increase in a pollutant in tissues of organisms at successive levels of a food chain:
biomagnification
The increase in concentration of a compound within an organism compared to the level found in the environment:
bioaccumulation
ex: PCBs in fatty tissues
biodegradation is the:
degradation of a pollutant(s) by a living organism, usually a microorganism
Remediation of a contaminated site using the biodegradative capacity of biology, usually microbiology:
bioremediation
What are the 3 things to consider to find the bioremediation sweetspot:
- matrix
- contaminant
- organism
For biodegradation/bioremediation to occur there are three essential interactions that need to overlap:
- contaminant must be biodegradable
- environmental physical/chemical parameters must allow biodegradation
- biodegradative microorganisms must be present and active in the contaminated environment
compounds alien to existing enzyme systems (foreign to life):
xenobiotic compounds
- man-made organic compounds with uncommon structure or properties
- not naturally occurring
- causes pollution problems due to toxicity, carcinogenicity, recalcitrance
xenobiotic
A compound that is attacked poorly, or not at all, by microbial enzyme systems because of molecular complexity ex: oligomerization (cellulose, polystyrene, plastics):
recalcitrance
What makes a contaminant recalcitrant:
- oligomerization
- halogen substitutions (H replaced by chlorine, fluorine, bromine
- other substitutions
- branching / alkylation
- molecules that are too large to fit into enzyme pockets containing catalytic sites, also large molecular organic comtaminants are more hydrophobic, less water soluble, therefore less bioavailable (ex: plastics, large molecular weight PAHs)
The insecticides mirex and kepone have _____________ that renders them extremely resistant to biodegradation
extensive chlorination
Which are biodegradable recalcitrant:
- alkanes
- PAHs
PAH with 2 rings =
naphthalene (non-carcinogenic)
PAH with 3 rings =
anthracene (non-carcinogenic)
PAH with 3 rings curved =
phenanthrene (non-carcinogenic)
PAH with 4 rings =
pyrene (non-carcinogenic)
PAH with 4 rings curved =
benz(a)anthracene (carcinogenic)
PAH with 5 rings =
benzo(a)pyrene (carcinogenic)
T or F: carbon-chloride ion bond is extremely hard to break which means hard to degrade
T
T or F: if new compounds that are synthesized are similar to existing natural compounds, microbes might be able to easily switch to metabolism of the new compounds
T
T or F: biodegradation can take a long time
T
What is the difference between soil and water in terms of microbes and pollutants:
pollutants and microbes in soils are easily located
Once isolated, strains could perhaps be improved via:
genetic engineering
Can zenobiotic be degraded by microbes?
it depends on the compound / for some compounds we just don’t know
What are some parameters that need to be optimal for biodegradative bacteria to do their work?
- soil moisture
- soil type
- aeration
- redox potential
- pH
- temperature
- nutrition status of the soil
T or F: surplus water limits oxygen transport in soils
T
oxygen is often ________ in soil and aqueous system. Necessary for aerobic respiration
limiting
T or F: microbial activity depends on pH
T
___________ require oxygen as an electron acceptor
aerobes
__________________ grow in either the presence or absence of O2
facultative anaerobes
_________________ oxygen is inhibitory (toxic) to growth, use other electron acceptors (nitrate, sulfate, ferric ion, carbon dioxide)
strict anaerobes
For their biodegradation/bioremediation, petroleum hydrocarbons require __________ conditions
aerobic
oxygen is required as both a terminal electron acceptor and a __________in oxygenase-catalyzed biodegradative reactions
substrate
T or F: oxygen is often limiting in soil and aqueous systems, oxygen concentration is often rate-limiting variable in petroleum degradation in soil and of gasoline in groundwater
T
What can you do to increase the aeration?
- Tilling
- Adding bulking agents in polluted soils systems (absorb and maintain water in the stool)
- Venting in aquifers
BTEX, PAHs, Halogenated organic compounds (TCE, PCBs, etc) require ___________ conditions
anaerobic
Biodegradation of organic contaminants under anoxic conditions occur under _____________, __________, ____________ and ____________ conditions
denitrifying
methanogenic
sulfate-reducing
iron-reducing
T or F: Halogenated hydrocarbons can act as alternative electron acceptors in anaerobic conditions
T
What are reductive dechlorination reactions?
substitution of Cl with H
T or F: Anaerobic degradation in subsoils and aqueous systems can be enhanced by supplying the appropriate electron acceptors: ex amend the matrix with nitrate or nitrous oxide for denitrification-coupled degradation
T
pH = 1/?
1/log(H+)
Bacteria have their optimal pH in which range:
6-9
Yeast have their optimal pH in which range
5-9
Acidophiles grow at pHs as low as 1.0 (______________)
Thiobacillus
the pH of soils vary between:
2.5-11.0
For petroleum hydrocarbons the optimal degradation is observed at pH _____
7.0-8.0
What can you do to bring the pH up:
add lime (calcium carbonate)
T or F: pH can affect water solubility and sorption of contaminants to soil and sediments
T
Increased acidity can result in increased solubility of ____________
heavy metals
Psychrophiles grow best at temperatures between:
15-20C
Psychrotrophs grow best at temperatures between:
30-35C
Mesophiles grow best at termperatures between:
45-50C
Thermophiles grow best at temperatures between:
80-110C
What is a Q10 value:
a change of 10C will generally increase or decrease enzyme activity by 2-fold
The biodegradation of compost materials occurs under: ____________ conditions
thermophilic
T or F: Raising temperatures of cantaminated soils (waters) can increase the rate of degradation by increasing microbial activity and solubility of contaminants
T
Temperature is hard to manipulate in the field except for ___________ and _________
biopiles and bioreactors
Soil moisture content represents the amount of water present in soil and is expressed as the ratio of ____________________
dry weight / wet weight
Water activity measures water actually _____________ for microbial use
available
What is the water activity required for microbes:
above 0.96
amount of water a soil can hold before becoming saturated:
water holding capacity
Optimal soil moisture content for aerobic microbial activity is _______ WHC
60-80%
Optimal soil moisture level is ________ of WHC for hydrocarbon degradation
30-90%
Dry soils and low soil moisture content leads to:
low Aw and decreased microbial activity
Waterlogged soils means:
WHC is greater than 100% = anoxic conditions
How can you decrease the soil moisture content in the field?
by drying or by amending the soil with agents that can bind to free water such as gypsum, or bulking agents such as alfalfa
In many contaminated environments, the rate-limiting inorganic nutrients are:
nitrogen and phosphorus
T or F: Usually in contaminated environments, K, S, Mg, Ca, Fe are present
T
What is the name of the process of treating contaminated matrices with additions of nitrogen and phosphorus:
biostimulation
In the bacterial cell, C:N = and C:P =
20: 1
50: 1
In soils systems the C:N is typically adjusted to 20:1-50:1 by adding nitrogen compounds such as: _________
NO3
NH4
Oleophilic fertilizers =
oil loving, they like alkane groups
Oleophilic fertilizers are used in ____________ systems, they are ___________ compounds containing nitrogen and phosphorus, they remain associated with oil contaminants
aqueous systems
hydrophobic
In many cases, complete mineralization is achieved by a _____________ of microorganisms present in the contaminated matrix
consortium
Mehtylobacter and Mehylococcus are
methanotrophs
Desulfovibrio =
sulfate reducing bacteria
Dehalococcoides, they remove ____________
chloride ions or chlorinated organics
Complete breakdown or degradation by a microorganism of organic compounds into inorganic compounds (CO2) =
MINERALIZATION
T or F: Hexadecane (C16H34) = CO2 + H2O + ENERGY (ATP) + BIOMASS
T
Uranium 6 to Uranium 4 =
biotransformation
Transformation by a microorganism of an organic or inorganic compound into another organic or inorganic compound, respectively
Biotransformation
The gratuitous metabolic transformation of a substance by a microbe growing on another substrate. The cometabilized substrate is not incorporated into the microrganism’s biomass and the microorganism does not derive energy from the transformation of the substrate=
Cometabolism
Example of cometabolism: cyclohexane is cometabolized in the presence of propane by ______________ allowing for commensal growth of pseudomonas on cyclohexane, and the transformation of cyclohexane to cyclohexanol
mycobacterium
