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Microbiology Final > Bioremediation and Biofuels > Flashcards

Bioremediation and Biofuels Flashcards

1
Q

How do microbes gain energy

A

-gain energy by catabolizing molecules
-microbes have evolved to extract energy from a diverse range of organic and inorganic molecules
-this allows microbes to play key roles in the circular economy

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2
Q

What is anaerobic degradation and why is it beneficial?

A

-anaerobic degradation sequentially removes chloride ions
-chlorinated solvent (PCE) are hazardous and not easily degraded
-microbes replace Cl w/ H (PCE -> ethene). Therefore less harmful to the environment

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3
Q

What is hydrocarbon decomposition

A

-bacteria consume hydrocarbons from the oil droplets and use as energy source
-oxidize the oil to CO2

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4
Q

What naturally occurring bacteria oxidize hydrocarbons

A

-fungi and green algae
-develop on oil films and slicks
-associate with oil droplets and concentrate at the oil-water interface

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5
Q

Describe the selection of microbes for hydrocarbon decomposition

A

-specific mobility/ adhesion mechanisms to attach to petroleum droplets
-ability to produce extra cellular emulsifying agents and survive in low O2 environs
-production of cell-bound inducible enzymes that depolymerize nutrient sources
-specific desorption mechanisms to release from petroleum droplets (exhausted food supply)
-biochemical pathway with enzyme production to degrade target wastes

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6
Q

What nutrients can be added to the oil spill area to increase bioremediation rates

A

Adding nutrients like phosphate and nitrogen

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7
Q

What is the main characterist of Radioactive bioremediation and one example

A

-can withstand high levels of radiation
-deinococcus radiodurans

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8
Q

How can deinococcus radiodurans withstand 1.5 million rads

A

-a specialized DNA repair protein that binds to the ends of DNA generated by radiation and protects it from damage by endonucleases

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9
Q

Describe Harris et al experiment with ionizing radiation

A

-expression of RecA, another DNA repair protein, was only increased 1.5 fold under the same conditions
-deletion of this ORF (renamed ddrA) resulted in increased sensitivity to ionizing radiation
-deletion of ddrA/DR0423 results in increased sensitivity to DNA damage

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10
Q

What is the mercuric reductase gene

A

-the mercuric reductase gene from E. coli has been cloned into D. radiodurans to detoxify the ionic mercury found in radioactive waste generated from nuclear weapons manufacture

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11
Q

What microbe breaks down plastics

A

-ideonella sakaiensis breaks down poly(ethylene trerphthalate) PEP, a component of plastics
-makes pits into the plastic

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12
Q

What is E-waste

A

-currently use giant magnets to recycle metals from laptops, phones, etc…

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13
Q

What microbes are involved in E-waste

A

-methylobacterium extorquens can be used to extract rare earth metals from e-waste
-M. extorquens grows on the sequesters lanthanides an other rare metals

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14
Q

What is the first step of sewage and wastewater treatment

A

-primary treatment: consists of removal of solids by passing it through a series of screens and letting the effluent stand for several hours to let the solids settle to the bottom (waste water sits in big tank to settle and go through multiple screens)

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15
Q

What is the secondary step of sewage and wastewater treatment

A

employs icrobes to reduce the organic load of the wastewater to environmentally acceptable levels (microbes used to break down organic molecules)

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16
Q

What is the tertiary step of sewage and wastewater treatment

A

uses chemical methods (precipitation, filtration, and chlorination) to remove inorganics like phosphate from wastewater (very expensive and not always done)
1)released to nature
2) goes back to drinking water

17
Q

What is broken down in anaerobic digestion in sewage and wastewater treatment

A

solids produced are broken down by anaerobic digestion

18
Q

explain the anaerobic digestion in the anoxic secondary treatment of sewage and wastewater treatment

A

-a set of digestive and fermentative reactions carried out by a variety of bacterial and archaeal species
0the efficiency is measured in terms of the percentage decrease in biological oxygen demand (BOD)
-BOD refers to the amount of oxygen that would be consumed if all the organics in one liter of wastewater were oxidized by bacteria, archaea, and protozoa
-The degradation process takes place in “sludge digestors” or “bioreactors”

19
Q

What is the trickling filter method in the aerobic sewage treatment

A

-the wastewater is sprayed onto a 2m deep bed of crushed rocks (organic matter is stuck to rocks)
-as the liquid slowly trickles through the bed the organic matter absorbs to the rocks allowing for microbial growth on the surface
-The microbes mineralize the organic matter to CO2, NH4, nitrate, sulfate, and phosphate

20
Q

What is the activated sludge method in the aerobic sewage treatment

A

-The wastewater is mixed and aerated in a large tank
-slime forming bacteria grow and form flocs
-the flocs attract protozoa, other small animals, and some bacteria and fungi
-the effluent containing the flocs is pumped to a clarifier where the flocs settle. Some are returned to the incubator to serve as an inoculum. The rest is sent to a sludge digestor

21
Q

What is the sludge tank in aerobic sewage treatment

A

-flocs sink to bottom + either go to
1) sludge return or
2) sludge digestion
-sludge digestor: actively breaks down organic matter + have 2 paths to is (solid + liquid)

22
Q

What is thermophilic sludge digestion

A

adding heat to the anaerobic digestion step
-pros: doubles or triples energy recovery by producing more biogas
-cons: more nutrients are released, complicating tertiary treatment (more nitrogen would be released into the environment)

23
Q

What biofuel

A

Conversion of biomass to liquid fuels

24
Q

What is biomass

A

is plant material, vegetation, or agricultural waste

25
Q

What are the basic biofuels

A

ethanol and biodiesel

26
Q

How is biodiesel made

A

from vegetable oil, animal fat, or esterified recycled cooking grease

27
Q

Why are desirable for biofuels

A

can be used to generate biomass quickly and with less resources than plants, while producing desired products

28
Q

What are some problems with ethanol

A

-plants use for ethanol take up fields for food
-are toxic at high concentrations
-require energy-intensive purification processes
-does not have the full fuel value of gasoline

29
Q

What is lignocellulose

A

plant dry matter (biomass) which is the most abundant raw material available on Earth for the production of biofuels, particularly ethanol

30
Q

What are the challenges of converting lignocellulosic biomass to fuels

A

-cellulose and hemicellulose are occluded by ligin
-lignin is recalcitrant to depolymerization
-inhibitors released from biomass during pretreatment

31
Q

What are the challenges with biomass composition and cellulases

A

-composition of cellulose/hemicellulose can impact fuel production
-a limited set of cellulase currently used to depolymerize cellulose
-cellulases have relatively low activity and are not robust to processing conditions

32
Q

What are first generation biofuels

A

-conventional biofuels
-made from things like sugar, starch, or vegetable oil

33
Q

What do first generation biofuels suffer from

A

-threatening the food chain
-increasing carbon emissions when planted outside traditional agricultural settings
-intense growth requirements

34
Q

What are second generation biofuels

A

-produces from sustainable feedstock
-advanced biofuels

35
Q

How is the sustainability of a feedstock defined

A

-availability
-impact on greenhouse gas emission
-impact on land use
-potential to threaten the food supply

36
Q

What are third generation biofuels

A

-an unofficial category reserved for biofuels derived from algae
-require a unique production mechanism and potentially offer solutions to mitigate most of the drawbacks of 1st and 2nd generation biofuels

37
Q

What is circular economy

A

-the circular economy is a model of production and consumption, which involves sharing, leasing, reusing, repairing, refurbishing and recycling existing materials an products as long as possible

Microbiology Final (8 decks)

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