Biodegradation

Question 1

Define biodegradation

Answer 1

• breakdown of complex chemical through biological processes (snipping, complete breakdown)

Question 2

What can be the result of biodegradation

Answer 2

• minor loss of functional groups
• fragmentation into larger constituents
• complete breakdown to CO2 and minerals

Question 3

What is the point of Alexander’s statement about how nothing that is naturally occuring is totally resistant to change?

Answer 3

• synthetic is not seen by ecological organisms - may not have tools to attack
• if we can mimic natural product it will be useable
• anything natural should be biodegradable

Question 4

What effects biodegradation?

Answer 4

• environmental conditions being favourable
  –>temp, pH, moisture, oxygen, nutrition

Question 5

Factors in decomposition of organic substrates

Answer 5

• elemental composition
  –> will it be toxic when broken down?
• structure of basic repeating units
• linkages between units
  –> ability to attack
• presence of nutrients
  -abiotic conditions
• presence of microbial community
  –> orientation (how to access matter)

Question 6

Define bioremediation

Answer 6

• use of biologically mediated processes to remove or degrade pollutants from environment

Question 7

What do bioremediation processes involve?

Answer 7

• nutrient movement
• modification of environment to accelerate biological processes with or without addition of other microorganisms

Question 8

Give an example of bioremediation

Answer 8

• removing a gas station, lift concrete (whats there)
  -add topsoil

Question 9

define GEMs

Answer 9

Genetically engineered microbes
- lab grown
–>when put in environment they died bc lab isolates them

Question 10

What conditions is microbial decomposition most rapid?

Answer 10

• between C10-C24

Question 11

What happens if <C9?

Answer 11

• if too small it can pass through cell membrane and may cause problems before they attack it
• toxic/violate it

Question 12

What happens if >C24?

Answer 12

• too complex, too hard to find point to attack

Question 13

How are C atoms joined in aliphatic hydrocarbons?

Answer 13

• open chains
• variation in length, degree of branching and # of double bonds

Question 14

is there anaerobic degradation of saturated aliphatic hydrocarbons

Answer 14

no

Question 15

What does saturated mean?

Answer 15

• no binding sites, no double/triple bonds

Question 16

Is there anaerobic degradation of UNsaturated aliphatic hydrocarbons?

Answer 16

some
***DOES NOT MATTER IF ENVIRONMENTAL FACTORS ARE NOT FAVOURABLE

Question 17

Define aromatic hydrocarbons

Answer 17

-Contain aromatic ring
- monoaromatic or polycyclic

Question 18

What does initial aerobic breakdown of aromatic hydrocarbons lead to?

Answer 18

something simpler for organisms to attack (can enter central metabolic cycles)

Question 19

What produces a straight chain compound anaerobically?

Answer 19

reductive ring cleavage (ring reduction and cleavage) = available for attack

Question 20

Explain what co-metabolic anaerobic process entails

Answer 20

• gratuitous (for free) transformation
• primary transformation for itself but other organisms take advantage of it

Question 21

Define xenobiotics, give an example

Answer 21

-chemically synthesized compounds that are not naturally occuring (man made)
- hard to attack
- ex. dyes, pesiticides

Question 22

Explain xenobiotic degradation

Answer 22

• multi-stage process
• microbial consortia involved
  **INFLUENCED BY ABIOTIC FACTORS

Question 23

What causes abiotic losses?

Answer 23

• leaching, volatilization
• may be attacked if other organic material is present as primary energy source

Question 24

What happens with partial breakdown of xenobiotics?

Answer 24

• end product can be more toxic (more mobile and taken up biologically (ex <C9 = toxic)

Question 25

Define cometabolism and give an example

Answer 25

• transformation while second substance serves as primary energy/carbon source
• ex. Propane –M.Vaccae –> energy + CO2
  —–>cyclohexane undergoes transformation (used by pseudomonas), M. Vaccae doesn’t care

Question 26

Examples of reductive dechlorination

Answer 26

• some better in anoxic conditions
• some breakdown in both

Question 27

Define Recalcitrant

Answer 27

• resistant to change

Question 28

Define pristine

Answer 28

• clear, unaffected, fresh

Question 29

Define meta effect

Answer 29

• increases resistance, occupies another area on structure and reduces ability to reach ring structure