EPOB 1210 Lecture 18, 1996
Fermentation

This has been the visit to this site since Oct. 8, 1996.

Word roots:

aero (L) = air
ferment (L) = yeast, leaven

FERMENTATION: = anaerobic catabolism of organic molecules.

no Krebs Cycle,
no O2 needed,
no ETC
All ATP from substrate level phosphorylation.

ANAEROBIC = life without oxygen
aerobic = life in the presence of oxygen

Fermentation starts with GLYCOLYSIS.

Oxidizing agent in glycolysis is NAD+
In fermentation, Pyruvate is then reduced to oxidize NADH back to NAD+ so e- end up being "dumped" on a carbon compound rather than on glucose.
FIG. 9.16

2 common fermentations:
1) Alcohol (ethanol) fermentation (beer, wine, bread etc.)
2) Lactic acid fermentation:
our muscles and bacteria that make yogurt etc.
(lactate is converted back to pyruvate in our livers)

Lactic acid fermentations are also important in food production
LACTIC ACID BACTERIA, Gram + bacteria that make yogurt, Cheeses, Kefir, Poi, Saurkraut etc.

Fermented products are preserved by the acid or ethanol.

Other fermentations (show overhead) lead to the production of other foods and industrial products (e.g. solvents, fuels, etc.)

ANAEROBIC RESPIRATION

e- transport chain present
Final electron acceptor is not O2 But rather e.g. NO3- or SO4--
Only certain bacteria can do anaerobic respiration e.g. denitrifying bacteria (who convert NO3- to N2 or N2O (gases) completing a big step in the Global N cycle.

Classification of organisms based on O2 use
Strict aerobes = require O2 for respiration (e.g. us overall)
Strict anaerobes = usually killed by O2 (e.g. certain fermentative and anaerobic respiring microbes, methanogens)
Facultative anaerobes = can go both ways (Yeast, many bacteria and our muscle cells)

FIG. 9.18

Review FIG. 9.19 metabolism of things other than glucose.

Vinegar Production from alcohol (a different type of aerobic respiration) by acetic acid bacteria (Gram -) overhead drawing

BIOSYNTHESIS (ANABOLIC PATHWAYS)

SHOW overhead

Production of polymers from monomers (using ATP as energy source)

Intermediate compounds from glycolysis and the Krebs cycle can be used to build monomers.

We can also use e.g. digested amino acids directly to make our own proteins.