MicrobiologyAN INTRODUCTION

EIGHTH EDITION

TORTORA • FUNKE • CASE

Chapter 5, part B

Microbial Metabolism

• Releases energy from oxidation of organic molecules

• Does not require oxygen

• Does not use the Krebs cycle or ETC

• Uses an organic molecule as the final electron acceptor

• Recycles NAD / NADH for Glycolysis

Fermentation

Fermentation

Figure 5.19

NAD is reduced to NADH in Glycolysis.

In fermentation the NADH is oxidized back to NAD to be used again.

There are many different types of fermentation, here is lactic acid and alcohol, but different organisms can produce different products.

Fermentation

Figure 5.18b

• Alcohol fermentation. Produces ethyl alcohol + CO2

• Lactic acid fermentation. Produces lactic acid.– Homolactic fermentation. Produces lactic

acid only.– Heterolactic fermentation. Produces lactic

acid and other compounds.

Fermentation

Fermentation

Figure 5.23

Lipid Catabolism

Figure 5.20

Triglycerides contain a glycerol and three fatty acid chains.

Fatty acid chains are broken down 2 carbons at a time (beta oxidation) to form acetate.

Protein Catabolism

Protein Amino acidsExtracellular proteases

Krebs cycleDeamination, decarboxylation, dehydrogenation

Organic acid

Protein Catabolism

Figure 5.22

Biochemical tests

Figure 10.8

• Used to identify bacteria.

• Photo: Conversion of light energy into chemical energy (ATP)– Light-dependent (light) reactions

• Synthesis: Fixing carbon into organic molecules– Light-independent (dark) reaction, Calvin-Benson cycle

• Oxygenic: 6 CO2 + 12 H2O + Light energy C6H12O6 + 6 O2 + 6 H2O

• Anoxygenic: CO2 + 2 H2S + Light energy [CH2O] + 2 A + H2O

Photosynthesis

Cyclic Photophosphorylation

Figure 5.24a

Noncyclic Photophosphorylation

Figure 5.24b

Figure 5.25

Table 5.6

• Halobacterium uses bacteriorhodopsin, not chlorophyll, to generate electrons for a chemiosmotic proton pump.