chapter 5: microbial metabolism. metabolism sum of all chemical rxn’s within a living organism...

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Chapter 5: Microbial Metabolism

METABOLISMMETABOLISM

• Sum of all chemical rxn’s within a living organism

• Release energy• Require energy

CATABOLIC REACTION (degradative)

• Breakdown of complex organic compounds into simpler ones

• Generally hydrolytic reactions (water used to break bonds)

• Exergonic (produce more energy than consume)

• Provide building blocks for anabolic rxns and energy needed to drive anabolic rxns

ANABOLIC REACTIONS (biosynthetic)

• Building of complex organic molecules from simpler ones

• Generally dehydration synthesis

• Endergonic (consume more energy than produce)

ATP <=> ADP + Pi + energy

Rxn’s all determined by enzymesand coupled together

Metabolism: Overview

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CD: Open with Firefox

But reactions happen very SLOWLY by

themselves....to make reactions go FASTER we

need.........

ENZYMES !

Enzymes• Biological catalysts• Each act on a specific substance (substrate)• Has active site for substrate to bind to

– “loading dock”• Each catalyzes only one reaction• Sensitive to temperature, pH, concentration• Can become denatured• All end in -ase







Enzymes• Large 3-D globular molecule

• Composed of two parts1. Protein portion (apoenzyme)– Inactive if alone

2. Nonprotein component (cofactor)– Ions of iron, zinc, magnesium or

calcium– If organic = coenzyme

• Together with the apoenzyme and cofactor = active enzyme (holoenzyme)

Enzymes: Steps in a Reaction

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CD animation: open with Firefox

Enzymes: Overview

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CD animation - open with Firefox

HOW DO YOU

CONTROL GROWTH OF BACTERIA??



CONTROL THEIR

ENZYMES!(Using inhibitors)

InhibitorsCompetitive Inhibitors• Fill the active site of an enzyme

and compete with the normal substrate for the active site

• Similar shape and chemical structure

• Does not produce products• Example: Sulfa drug

Animation: CD



InhibitorsNoncompetitive Inhibitors• Do not compete with the substrate; instead interact with

another part of the enzyme• Binds and causes the active site to change its shape, making

it nonfunctional• Allosteric inhibition “other space”Animation: CD





Carbohydrate Catabolism• Most microorganisms use

carbon as primary energy source

• Oxidation of glucose1. Cellular

Respiration Glycolysis Krebs cycle Electron Transport Chain

2. Fermentation Glycolysis Products: Alcohol or lactic

acid



Fermentation• Releases energy

from sugars or other organic molecules

• Does not require oxygen

• Produces only a small amount of ATP









Alcohol Fermentation: •Saccharomyces (yeast)

Heterolactic: produce both

Lactic Acid Fermentation• Homolactic: only make lactic acid•Streptococcus• Lactobacillus• Bacillus

Lipid and Protein Catabolism

LIPIDS• Produce enzymes called lipases• Break down into fatty acid and glycerol• Put into the Kreb cycle• Also use this to break down petroleum products -

oil spills

PROTEINS• Produce proteases

and peptidases• Convert proteins into

different substance and enter Kreb cycle



Photosynthesis

• Conversion of light energy into chemical energy• Chemical energy then used to convert CO2 into

sugars (carbon fixation)• Cyanobacteria• Animation



REVIEW

• Cellular Respiration– Aerobic– Carbon

• Fermentation– Anaerobic– Carbon

• Photosynthesis– Carbon Fixation– Light energy

• Protein Catabolism– Use Kreb Cycle

• Lipid Catabolism– Use Kreb Cycle

Classifying Bacteria-Nutritional Pattern

HOW DO THEY GET

ENERGY?Phototrophs: use light as

primary energy sourceChemotrophs: use

reactions of inorganic or organic compounds for energy

HOW DO THEY GET

CARBON?

Autotrophs: CO2 as principle carbon source

Heterotrophs: organic carbon source

PHOTOAUTOTROPHS

Energy: light

Carbon: CO2

Examples: cyanobacteria

Green and Purple Bacteria - use sulfur or hydrogen gas to reduce CO2 and make organic compounds, not H20

Do not produce O2

(Anoxygenic)



Chromatium -Purple BacteriaFound in sulfide-containing freshwaterhabitats



Chlorobium- Green Bacteriafound in hotsprings, cold lakesand sediments

PHOTOHETEROTROPHS

Energy: LightCarbon: organic compoundsAnoxygenic

Examples:Green nonsulfur bacteria

Chloroflexus (found in hot springs, lakes,

hyersaline environments)

Purple nonsulfur bacteriaRhodopseudomonas

(found in soil and marine environments)





CHEMOAUTOTROPHS

Energy: inorganic compounds

Ex: H2S, S, NH3, H2, CO

Carbon: CO2

-fix CO2

Example:

Beggiatoa - use H2S, found in soil, sulfur springs, mud layers of lakes,

Deep Sea Vents http://www.teachersdomain.org/asset/tdc02_vid_deepseavents/



http://www.teachersdomain.org/asset/tdc02_vid_deepseavents/

http://www.teachersdomain.org/asset/tdc02_vid_deepseavents/

CHEMOHETEROTROPHS

Energy: organic compoundsEx: glucose

*use the electrons from H-atoms as energy source

Carbon: organic compound*Hard to distinguish-use the same

compound

Example:Streptococcus pneumonia - fermentation



• http://people.eku.edu/ritchisong/RITCHISO/energyflowchart.jpg

• http://www.hepafilters.com/images/microbes.jpg• http://www.bio12.com/ch6/RemedialEnzymes_file

s/image007.jpg• http://classes.midlandstech.edu/carterp/Courses/bi

o225/chap05/Slide13.GIF

http://people.eku.edu/ritchisong/RITCHISO/energyflowchart.jpg

http://www.hepafilters.com/images/microbes.jpg

http://www.bio12.com/ch6/RemedialEnzymes_files/image007.jpg

http://www.bio12.com/ch6/RemedialEnzymes_files/image007.jpg

http://classes.midlandstech.edu/carterp/Courses/bio225/chap05/Slide13.GIF

http://classes.midlandstech.edu/carterp/Courses/bio225/chap05/Slide13.GIF

chapter 5: microbial metabolism. metabolism sum of all chemical rxn’s within a living organism...

Documents

chemical energychemical

primary energy sourcechemotro

overviewinsert enzymes

reactioninsert enzymes

jpgcd animation open

kreb cyclealso use

active sitesimilar shape

calciumif organic