kuliah mikro umum metabolisme 2011 new

7/13/2019 Kuliah Mikro Umum Metabolisme 2011 New

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Metabolism of Bacteria

By

Ms.Patchanee Yasurin

471-9893

Faculty of Biotechnology

Assumption Univerity


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Why do we must know the

metabolism of bacteria ?

Because we want to know how to inhibitor stopbacteria growth and want to control

their metabolism to prolong shelf-lifeof

food products.


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What is Metabolism? The Greek metabole, meaning change

It is the totality of an organism's chemical

processes to maintain life.

- Catabolism- Anabolism


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What are nutrients that bacteria want?

C Sugar, Lipid Energy, Biosynthesis

N Protein Biosynthesis

O Air Energy


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Biochemical Components of Cells Water: 80 % of wet weight

Dry weight

Protein 40-70 %

Nucleic acid 13-34%

Lipid 10-15 %

Also monomers, intermediates and

inorganic ions


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Microorganisms require about ten elements in large

quantities, because they are used to construct

carbohydrates, lipids, proteins, and nucleic acids.

Several other elements are needed in very small

amounts and are parts of enzymes and cofactors.

Concepts:

Nutrientrequirements


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Macronutrients Cells make proteins, nucleic acids and

lipids

Macronutrients

macromolecules, metabolism

C, H, O, N, S, P, K, Mg, Fe

Sources

Organic compounds

Inorganic salts


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Micronutrients and growth

factors Micronutrients: Metals and metalloids

Elements needed in trace quantities

Generally not necessary to add to medium Deficiencies can arise when medium constituents

are very pure

Growth factors: organic requirements

Vitamins, amino acids, purines, pyrimidines,

acetate


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micronutrients: required in lesser,

sometimes trace

amounts

not every element is

required by all cells


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growth factors:organic compounds required in small amountsnot every growth factor is required by all cells


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A. Basic Concepts Definitions

Metabolism: The processes of catabolism and

anabolism Catabolism: The processes by which a living

organism obtains its energy and raw materialsfrom nutrients

Anabolism: The processes by which energyand raw materials are used to buildmacromolecules and cellular structures(biosynthesis)


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Overview of cell metabolism


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Breakdown

Proteins to Amino Acids, Starch to Glucose

SynthesisAmino Acids to Proteins, Glucose to Starch


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Bacterial Metabolism

Exoenzymes: Bacteria cannottransport large polymers into the cell.They must break them down intobasic subunits for transport into thecell. Bacteria therefore elaborateextracellular enzymes for thedegradation of carbohydrates to

sugars (carbohydrases), proteins toamino acids (proteases), and lipids tofatty acids (Lipases).


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After Sugars are made or obtained, they are

the energy source of life.

Breakdown of sugar(catabolism) different

ways:

Aerobic respiration Anaerobic respiration

Fermentation

Energy Generating Patterns


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Aerobic respiration

Glucose is a hexose, monosaccharide, C6H12O6 It is systematically broken down through

three related pathways to Carbon dioxide

(CO2) and Water (H2O) Process:

1. Glycolysis (in cytoplasm)

2. Kreb Cycle (in mitochondria)

3. Electron transport chain


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Glycolysis: Several glycolytic pathways

The most common one:

glucose----->pyruvic acid + 2 NADH +2ATP


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Section 8 1: Glycolysis

Figure 8.3 Glycolytic Pathway

From McKee and McKee, Biochemistry, 5th Edition, 2011 Oxford University Press


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Section 8 1: Glycolysis

Figure 8.3 Glycolytic

Pathway

From McKee and McKee, Biochemistry, 5th Edition, 2011 Oxford University Press


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Glycolysis


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Glycolytic Pathways

4 major glycolytic pathways found in differentbacteria:

Embden-Meyerhoff-Parnas pathway

Classic glycolysis

Found in almost all organisms Hexose monophosphate pathway

Also found in most organisms

Responsible for synthesis of pentose sugars used in

nucleotide synthesis

Entner-Doudoroff pathway

Found in Pseudomonasand related genera

Phosphoketolase pathway

Found in Bifidobacteriumand Leuconostoc


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cyclic pathway

Pyruvic acid is first acted on by an NZ and a coenzyme (COA). The end productis Acetyl-Coa and a CO2molecule.

Remember this occurs twice for each glucose molecule. (One glucose is split into

two pyruvic acid molecules.)


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TCA Cycle(Krebs)


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Return to Krebs and show how it works with electron transport chain. Note how

glycolysis and Krebs are working together. Note that each produces reducedcarriers that need to be processed.


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Carbohydrates,

fats, and proteins

can all becatabolized

through the same

pathways.

Copyright 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 9.19


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Lipid Metabolism

Lipids are essential to the structure and function of

membranes

Lipids also function as energy reserves, which can

be mobilized as sources of carbon

90% of this lipid is triacyglycerol

triacyglycerol lipase glycerol + 3 fatty acids

The major fatty acid metabolism is -oxidation


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Lipids are catabolized to Glyerol and Fatty

acids Glycerol easily enters glycolysis and Krebs

just like pyruvate

Fatty acids are chopped into 2 or 3 acidfragments that are broken downt to

carbondioxide

Even nucleic acidsOH SO MUCHMORE!!! Take biochem.


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Lipid Metabolism

-oxidation of fatty acid


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Lipid Metabolism

Glycerol Metabolism


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Other fuels

Proteins: digested to amino acids

Amino acids are :

deaminated : amino group removed,the reulting acid can be further

metabolized, more ATP

decarboxylated: carboxyl group

removed, the end products then

enter glycolysis or Krebs to make ATP


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Nitrogen Metabolism

Nitrogenis an essential element ofbiological molecules, such as amino acids,

nucleotides, proteins, and DNA

Bacteria vary widely in their ability to

utilize various sources of nitrogen for

synthesis of proteins


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General view of nitrogen metabolism


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Amino acid degradation


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Pathways Involved in Nitrogen Utilization

1. Protein Digestionby proteinase and peptidase2. Oxidative Deamination


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3. Reductive Deamination

4. Decarboxylation


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5. Transamination Reactions


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Anaerobic respiration

Final electron acceptor : never be O2

Sulfate reducer: final electron acceptor is sodium

sulfate (Na2 SO4)

Methane reducer: final electron acceptor is CO2

Nitrate reducer : final electroon acceptor is

sodium nitrate (NaNO3)

O2/H2O coupling is the most oxidizing, more energy

in aerobic respiration.

Therefore, anaerobic is less energy efficient.


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Chemoautotroph:

Nitrifying bacteria

2 NH4++ 3 O2 2 NO2- + 2 H2O + 4 H++ 132 Kcal

Bacteria Electron

donor

Electron

acceptor

Products

Alcaligens and

Pseudomonas sp.H2 O2 H2O

Nitrobacter NO2- O2 NO3

-, H2O

Nitrosomonas NH4+ O2 NO2- , H2ODesulfovibrio H2 SO4 2- H2O. H2SThiobacill us deni tri fi cans S0. H2S NO3

- SO4 2- , N2

Thiobacill us ferrooxidans Fe2+ O2 Fe3+ , H2O


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C. Fermentation Features of fermentation pathways

Pyruvic acid is reduced to form reduced

organic acids or alcohols. The final electron acceptor is a reduced

derivative of pyruvic acid

NADH is oxidized to form NAD: Essential

for continued operation of the glycolyticpathways.

O2is not required.

No additional ATP are made.

Gasses (CO2and/or H2) may be released


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Fermentation Glycosis:

Glucose ----->2 Pyruvate + 2ATP + 2NADH

Fermentation pathwaysa. Homolactic acid F.

P.A -----> Lactic Acid

eg. Streptococci, Lactobacilli

b.Alcoholic F.

P.A -----> Ethyl alcohol

eg. yeast


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Some organisms (facultative anaerobes),

including yeast and many bacteria, can survive

using either fermentation or respiration. For facultative anaerobes,

pyruvate is a fork in the

metabolic road that leads

to two alternative routes.

Copyright 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 9.18


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Re-Dox Reactions


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CentralMetabolism


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Glycolysis

Fermentation Products


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Nutrition

Table 27.1


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Alternative energy generating

patterns(3)


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Alternative energy generating

patterns(4)


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Energy/carbon classes of organisms


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Fig. 5-12


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Overview of Metabolism


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Electron Transport Chain


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Electron Flow


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Electron Flow

and Energy

Trapping


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Microbiology chapters 7 - 8 part 2

Glycolysis: Anaerobic, no oxygen required, linear NZ pathway

Begins with ______End products _________

How much ATP? _______

How many carrier molecules? ____

Name the carrier molecule. ____

Where in the cell? _______

What happens after if the organism

Is an aerobe? _____

Facultative? ______

Strict anaerobe? ______

Aerobe deprived of oxygen? ____


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ATPAdenosine triphosphate, universal cellular energy

Cyclically made and energy is stored and then broken down and theenergy is released


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ATPAdenosine triphosphate, universal cellular energy

Cyclically made and energy is stored and then broken down and theenergy is released


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Note: ATP is a ribonucleotide, it has ribose, a nitogenous base

(adenine), and phosphate. The high energy bond of the terminal ofthe three phosphates is the one cyclically broken and regenerated.

Sugars like glucose can be broken down in a catabolic pathway

controlled by many cellular enzymes. Some of the energy releasedby the breaking of covalent bonds is harvested and stored in the

energy bonds of ATP.

Most any biomolecule can be used for energy; we will focus on thecatabolism of glucose (a monosaccharide) and later show how the

others are involved (lipids, AA, etc)


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Note: ATP is a ribonucleotide, it has ribose, a nitogenous base

(adenine), and phosphate. The high energy bond of the terminal ofthe three phosphates is the one cyclically broken and regenerated.

Sugars like glucose can be broken down in a catabolic pathway

controlled by many cellular enzymes. Some of the energy releasedby the breaking of covalent bonds is harvested and stored in the

energy bonds of ATP.

Most any biomolecule can be used for energy; we will focus on thecatabolism of glucose (a monosaccharide) and later show how the

others are involved (lipids, AA, etc)


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This is a cyclic pathway

Pyruvic acid is first acted on by an NZ and a coenzyme (COA). The end productis Acetyl-Coa and a CO2molecule.

Remember this occurs twice for each glucose molecule. (One glucose is split into

two pyruvic acid molecules.)

K b l (TCA Ci i id l ) A bi O i h


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Krebs cycle (TCA, Citric acid cycle) Aerobic stage, Occurs in the

fluid of the Matrix


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This is a cyclic pathway Pyruvic acid is

first acted on by an NZ and a coenzyme

(COA). The end product is Acetyl-Coa

and a CO2molecule.

Remember this occurs twice for each

glucose molecule. (One glucose is splitinto two pyruvic acid molecules.)


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Return to Krebs and show how it works with electron transport chain. Note how

glycolysis and Krebs are working together. Note that each produces reducedcarriers that need to be processed.


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The electrons are passed down the chain and end up being added to oxygen. The Hydrogen ion (H+) is pumped out

(proton pump) and flows back in at special sites to be added to the Oxygen and electron to form Water. Energy is

conserved (harvested; stored) in the bonds of ATP


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Theory of Chemiosmosis: Proton pump, increased H+ ion concentration, flow

through ATP synthase related channel, energy is harvested in high energy bondsof ATP. Enough to generate 34 more ATP.

Carbohydrate Metabolism


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y

2. EntnerDoudoroff (ED) pathway

Carbohydrate Metabolism


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Ca bo yd ate etabo s

3. Pentose phosphate (PP) pathway


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Formation of intermediates of the EmbdenMeyerhofParnas

(EMP) and EntnerDoudoroff (ED) pathway from carbohydratesother than glucose

Table 1:Distribution of EmbdenMeyerhofParnas


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(EMP), EntnerDoudoroff (ED), and pentose phosphate(PP) pathway in bacteria

Organism EMP ED PP

Pseudomonas aeruginosa - +i -

Enterococcus faecalis + +i +

(Streptococcus)

Salmonella typhimurium + +i +Bacillus subtilis + - -

Escherichia coli + +i +

Yersinia pseudotuberculosis + +i -

Remark: + = Present;

= not present.

i = inducible

kuliah mikro umum metabolisme 2011 new

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