Biodegradation Flashcards
Define biodegradation
- breakdown of complex chemical through biological processes (snipping, complete breakdown)
What can be the result of biodegradation
- minor loss of functional groups
- fragmentation into larger constituents
- complete breakdown to CO2 and minerals
What is the point of Alexander’s statement about how nothing that is naturally occuring is totally resistant to change?
- 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
What effects biodegradation?
- environmental conditions being favourable
–>temp, pH, moisture, oxygen, nutrition
Factors in decomposition of organic substrates
- 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)
Define bioremediation
- use of biologically mediated processes to remove or degrade pollutants from environment
What do bioremediation processes involve?
- nutrient movement
- modification of environment to accelerate biological processes with or without addition of other microorganisms
Give an example of bioremediation
- removing a gas station, lift concrete (whats there)
-add topsoil
define GEMs
Genetically engineered microbes
- lab grown
–>when put in environment they died bc lab isolates them
What conditions is microbial decomposition most rapid?
- between C10-C24
What happens if <C9?
- if too small it can pass through cell membrane and may cause problems before they attack it
- toxic/violate it
What happens if >C24?
- too complex, too hard to find point to attack
How are C atoms joined in aliphatic hydrocarbons?
- open chains
- variation in length, degree of branching and # of double bonds
is there anaerobic degradation of saturated aliphatic hydrocarbons
no
What does saturated mean?
- no binding sites, no double/triple bonds
Is there anaerobic degradation of UNsaturated aliphatic hydrocarbons?
some
***DOES NOT MATTER IF ENVIRONMENTAL FACTORS ARE NOT FAVOURABLE
Define aromatic hydrocarbons
-Contain aromatic ring
- monoaromatic or polycyclic
What does initial aerobic breakdown of aromatic hydrocarbons lead to?
something simpler for organisms to attack (can enter central metabolic cycles)
What produces a straight chain compound anaerobically?
reductive ring cleavage (ring reduction and cleavage) = available for attack
Explain what co-metabolic anaerobic process entails
- gratuitous (for free) transformation
- primary transformation for itself but other organisms take advantage of it
Define xenobiotics, give an example
-chemically synthesized compounds that are not naturally occuring (man made)
- hard to attack
- ex. dyes, pesiticides
Explain xenobiotic degradation
- multi-stage process
- microbial consortia involved
**INFLUENCED BY ABIOTIC FACTORS
What causes abiotic losses?
- leaching, volatilization
- may be attacked if other organic material is present as primary energy source
What happens with partial breakdown of xenobiotics?
- end product can be more toxic (more mobile and taken up biologically (ex <C9 = toxic)
Define cometabolism and give an example
- 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
Examples of reductive dechlorination
- some better in anoxic conditions
- some breakdown in both
Define Recalcitrant
- resistant to change
Define pristine
- clear, unaffected, fresh
Define meta effect
- increases resistance, occupies another area on structure and reduces ability to reach ring structure
