Unit 2 - lecture 6

Question 1

what is a hydrocarbon

4 used as an energy source for microbes

Answer 1

• an organic compound consisiting of hydrogen and carbon
• highly conbustible and the main energy sourve of the world
• great electron donors
• alkanes, alkenes, aromatic hydrocarbons, PAH
• MUST be activated with O2 to be used = oxygenation

Question 2

hydrocarbons

explain the enzymes that activate hydrocarbons

Answer 2

• Oxygenases = catalyze the incorporation of O2 into the organic compounds
• Monooxygenase = incorporates only one atom of O2 in organic compound; other is reduced to H20
• dioxygenase = incorporate both O2 atoms into the molecule

Question 3

hydrocarbons

what is the difference with aliphatic and aromatic hydrocarbons

products and integration into central carbon metabolism

Answer 3

aliphatic:
- product: Fatty acid
- FA metabolized through beta oxidation = acetyl-CoA and NAD; products used in central carbon metbaolism
aromatic:
- inital stage: catechol formation
- catechol is formed and cleaved to compounds that can enter central carbon metabolism

Question 4

Aerobic methanotorphy

exaplain the metabolism of methane (CH4)

key enzyme and forms, and mode of assimiliation

Answer 4

• methane and other c1 compounds - carbon and energy source
• known as methanotrophs; oxidation of methane/methanol is aerobic process
• monooxygenase (MMO)
• GAMMAPROTEOBACTERIAL METHANOTROPHS - Ribuloso Monophospate Cyle (RuMP)
• ALPHAPROTEOBACTIERAL METHANOTROPHS - Serine cycle
  MMO:
  1. particulate MMO - embedded in the membranes, requires copper
  2. Soluble MMO - freely floating in cytosol, requires iron

Question 5

Aerobic methanotorphy

what are the special types of methanotrophs

2

Answer 5

• type X methanotrophs (older literature) - perform RuMP and Serine cycle
• VERRUCOMICROBIA METHANOTROPHS - lives at pH 2.0 and high temperature, assimilates CO2 via Calvin Cycle