L3 - Microbial Metabolic Abilites Flashcards
What is a big molecule that’s a problem and what are its features?
Lignin
2nd most abundant polymer after cellulose
amorphous structure very difficult for microbes to get at
Waste product of paper industry
What are other big molecules of polymers and eg?
PAHs - poly-aromatic-hydrocarbons
e.g. anthacene, pentacene
Why are PAHs a problem?
Several rings linked together difficult to break apart
What are two toxic organics?
Cyanides, Phenol
What are the features of the toxic organics - cyanides?
Range of compounds containing C=-N
Commonly form at former gas works
Inhibits electron transport chain so doesn’t affect fermentative growth in anaerobic conditions
What are the features of the toxic organic phenol?
Disrupts membranes
Used as an antimicrobial
Example of a highly toxic inorganic?
Methylmercury acts as a neurotoxin
What are problems microbes face in bioremediation?
Physically getting at pollutant
How to get it into cell
How to survive in its presence
How to get energy or carbon
How do microbes get at large molecules?
Produce extracellular enzymes
A range of oxidative enzymes such as peroxidases, endo and exocellulases
Produce free radicals that randomly break bonds (smash and grab)
How can microbes get to water insoluble compounds like oil?
Use of biosurfactants eg glycolipids, phospholipids, lipoproteins
How do biosurfactants work?
Migrate to interface of water and oil (hydrophobic side towards oil).
Redcues interfacial tension allowing greater mixing
Formation of micelles
Pseudo-solubilises the oil
How do microbes get oil into their cell?
Direct uptake - microbes attach to droplets of oil emulsified by surfactants
How do cells perform pseudo- stabilisation/solubisation?
Hydrophobic compartments on cell wall of some yeasts - alkane/surfactant complex dissociates within this
What are examples of processes used by microbes to detoxify toxic compounds?
Hydrolysis Hydroxylation Demethylation Methylation Dehalogenation
What is dehalogenation and what is it used on?
Taking off a chlorine
Pesticides and industrial wastes are chlorinated