Biological Methods-Basic Microbial Metabolism

							Biological Methods 10.1-Basic Microbial Metabolism 10.2 Biodegradation of Xenobiotics
Materials are taken from the Textbook: Hazardous Waste Management. 2nd Ed. Legrega et al., McGraw Hill

Terminology
• Microorganisms
– By cell structure
• Procaryote • Eucaryote

– By cell function
• Autotrophic • Heterotrophic

• Cellular Metabolism
– Anabolism – Catabolism

Common Microorganisms
• • • • Bacteria Fungi Algae Protozoa

Heterotrophic Photoheterotrophic Light Organic carbon Chemoheterotrophic Oxidation-reduction reactions of Organic carbon organic compounds

Factors Affecting Biodegradability
• • • • • Energy and substrate sources Enzymatic processes Substrate biodegradability Inhibition and toxicity Microbial community

Biodegradability
• Straight chair aliphatic : easily degraded; branching: strictly hindered configuration resistant to degradation; unsaturated aliphatic: less readily transformed than saturated analogues. • Simple aromatics: degradable by several mechanisms of ring cleaving; substituted by halogens decreases degradability; even highly chlorinated aromatics, PCBs can be degraded even slowly • Nitrogen and sulfur compounds are linked to their uses as nutrients; branched are difficult. • Polymeric materials are the most difficult.

Anaerobic Processes

Engineering Factors

Oxygen Requirements

• Oxygen requirement for anabolic metabolism of alkene to cellular material
Under anaerobic condition, the oxygen demand is supplied from water , not oxygen. C7H12 + 14H2O  7CO2 + 40 e + 40 OH5O2 + 20 H+ + 20e  10 H2O 5CO2 + NH3 + 20 H+ + 20 e  C5H7O2N + 8 H2O C7H12 + NH3 + 5O2  C5H7O2N + 2CO2 + 4H2O

•Summary of chemical equation for the anabolic alkene conversion to biomass C7H12 + NH3 + 5O2  C5H7O2N + 2CO2 + 4H2O

The new cellular material if mineralized during endogenous respiration also exerts oxygen demand C5H7O2N + 5O2  2H2O + NH3 + 5CO2 Overall C7H12+ 10O2  7CO2 + 6H2O