Bio(degradation/remediation/catalysis)

Question 1

Biodegredation

Answer 1

organisms do during metabolism, reduction of complex chemicals, can be complete or partial

Question 2

Bioremediation

Answer 2

exploit biodegradation for clean-up purposes, remove unwanted chemicals or detoxify

Question 3

Biocatalysis

Answer 3

exploit microbes for industrial use

Question 4

Spill cleanup

Answer 4

hydrocarbon degrading microbes clean up sites- bioremediation

Question 5

Complete Biodegradation

Answer 5

Mineralization- conversion of C,N,P,S and other elelments to inorganic products eg.CO2,NH4)

Question 6

Partial Biodegradation

Answer 6

Biotransformation- transform compound to a more stable/less toxic/more useful compound

Question 7

Principle of Microbial infallibility

Answer 7

no natural organic compound is totally resistant to biodegration in fav conditions

Question 8

Xenobiotic

Answer 8

chemical that isnt normally found in a living organism or expected to be produced by it

Question 9

factors influencing biodegradability/rate of biodegradation

Answer 9

pH, temp, organic matter content, availability of target compounds, only dissolved hydrocarbon units are available to degraders

Question 10

Compound degradability depends on

Answer 10

element composition, structure: branching, repeating units, linkage, arrangement
of substituents (more Cl- increases persistence)

Question 11

Hydrocarbon biodegradation

Answer 11

degraders are found everywhere, most are aerobic using oxygenases

Question 12

Methane and Hydrocarbon biodegradation

Answer 12

degraded my specialized C1 microorganisms (methanotrophs)

Question 13

Aliphatics and degradation

Answer 13

• up to C9 can be toxic, biodegradable, volatile
• C10-C24 or branching decrease biodegradability
• unsaturated are more rapidly degraded than saturated
• (most to least degraded ) alkanes, aromatics, alicyclics

Question 14

Beta - Oxidation of fatty acids

Answer 14

2C units (acetyl CoA)
feeds into central metabolism (TCA Cycle) and reducing power (FADH, NADH), used to generate ATP or directly in biosynthesis

Question 15

oxidation of aromatic hydrocarbons

Answer 15

-oxygenases (di- or mono-)
-initial steps lead to catechols, protocatechuate (aromatic rings with adjacent –OHs)
-subsequent ring cleavage between hydroxyl groups (ortho fission), beside the hydroxyl groups (meta fission)
eventual formation of compounds that enter central metabolic pathways (TCA cycle)
“funnelling” of many different aromatic compounds (including substituted aromatics) through a few key intermediates (e.g., catechols) to common pathways

Question 16

anaerobic biodegradation of aromatic compounds

Answer 16

ring reduction followed by ring cleavage to form fatty acid
β-oxidation to acetyl-CoA & propionyl-CoA units
added oxygen is from H2O not O2
BTEX compounds may be slowly biodegraded by similar pathway in absence of oxygen

Question 17

cometabolism

Answer 17

transformation of a substanve while a second serves as a primary growth substrate

Question 18

Biocatalysis example

Answer 18

naphthalene dioxygenase catalyzes first step of aerobic naphthalene degradation
- has a broad substrate range, can be used for lots of catalysis

Question 19

Biodegradation of xenobiotics

Answer 19

loss can be from biotic and abiotic reasons: volatile rxns, leaching, spontaneous decomposition, biological reactions

Question 20

Reductive dechlorination

Answer 20

PCE or TCE, requires electrons + H+; Cl- is released

• cis-DCE is usual DCE intermediate in biological reduction
• this pathway occurs in anoxic, low redox environments
• microorganisms most efficient at this conduct dehalorespiration (chloroalkene = terminal electron acceptor in anaerobic respiration)

Question 21

Biodegradation of 2,4,5-T by Burkholderia cepacia

Answer 21

• O2 required (i.e., oxic environments)
• note –Cl replacement by -OH
• note substituted catechol formation; subsequent ring fission
• note 2,4,5-T is used as a growth substrate; succinate, acetate feed into central metabolic pathways

Question 22

Plastics

Answer 22

• polymers of polyethylene, polypropylene, PVC

- recalcitrant xenobiotic compounds

Question 23

Biodegradable plastics

Answer 23

starch linked polymers, plastics based on microbial storage polymers