2. Metabolism
2
โซSum total of all the chemical reactions occuring
in thecell ( i.e. biosyntheticand degradative)
โซMetabolism in bacteria is essential for their
existance , for environment , and products are
commerciallyand medically important for human
beings.
3. CATABOLIC AND ANABOLIC REACTIONS
โซReactions that cause
breakdown of complex
molecules intosimpler
form with relase of
energy is catabolic
reactions.
โซEnergy requiring
reactions that build up
complex organic
molecules from simpler
ones is anabolic
reactions.
3
5. Components of metabolism
COMPONENTS FUNCTIONS
5
Enzymes Biological catalyst, fascilitateseach stepof metabolicreaction
by lowering theactivation energyof reaction.
Adenosine triphosphate
(ATP)
serves as energycurrencyof cell ,
Energy source Compund that is oxidised to releaseenergy
, alsocalled an electrondonor.
Electron carriers carry the electrons that are removed during the oxidation of
energysource (NADโบ, NADPโบ , and FAD ( theirreduced form
NADH , NADPH , and FADHโ) .
Precursor metabolites Intermediate metabolite that link anabolicand catabolic
pathways, like pyruvate, acetyl-coA, glucose -6-p, etc.
8. Role of ATP
โซIsenergy currencyof cell,
serving as ready and
immediatedonor of free
energy.
โซEnergy is releases when
phosphate bond is broken,
hence it is called high
energy phosphate bond.
โซSynthesis and breakdown of
ATP continuously occurs in
cell during degradative and
synthetic process.
8
9. Generation of ATP
Bacteria uses three mechanism of
phosphorylation to generate ATP
from ADP.
1)Substrate level
phosphorylation
C-C-C-P + ADP C-C-C + ATP
In this mechanism , a high energy
phosphate from a phosphorylated
substrate is directly transferred to
toADP.
9
10. Contdโฆ
10
2) Oxidativephosphorylation:
ATP generation duting ETC.
3)Photophosphorylation
โซOccurs in phototrophs.
โซDerive ATP using radiant energyof the sun.
โซThese ATP are then utilized tosynthesize mainly
glucose .
12. GLYCOLYSIS
โซ Embden-Mayerhof Parnas
pathway.
โซ Stepwise Conversion of glucose to
pyruvate and each step require
specific enzyme.
โซ Occurs in cytosol.
โซ Does not require oxygen and hence
occur in both aerobicand anaerobic
bacteria.
โซ Three phases :- preparatory phase,
splitting phase and energygeneration
phase.
โซ 2 moleculesof pyruvic acidsare
formed from eachglucose .
โซ Net gain of 2 ATP by substrate
level phosphorylation and
formationof 2 reduced substrate
i.e. NADH(6 ATP).
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14. Pathways alternative to glycolysis
14
โซMany bacteria have another pathway in addition to
glycolysis fordegradation of glucose.
1) Pentose phosphatepathway, and
2) Entner Doudoroff pathway.
15. Pentose phosphate pathway
โซ Hexose monophosphateshunt. biosyntheticreactions.
โซ Occurs simultaneouslywith
glycolysis and provides
breakdownof both pentosesugar
and glucose.
โซ Important Feature :- intermediate
pentoses are used for nucleic
acid synthesis, aminoacid
synthesis and glucose from CO2
in photosynthetics.
โซ Importantproducerof reduced
coenzyme i.e. NADPH , used for
15
16. Entner โDoudoroff pathway
โซ Bacteria having enzyme for
EntnerโDoudoroff pathway
can metabolizewithoutglycolysis
or PPP.
โซ Found in some Gram negative
bacteria like Psedomonas spp,
Rhizobium,etc.. and generally
not found in Gram positive
bacteria.
โซ Produces 1 molecule NADH, 1
molecule NADPH and 1 molecule
of ATP ( from 1 glucose).
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17. Cellular respiration and fermentation
17
โซPyruvate obatained from glucose breakdown are
channeled eitherto respiration or to fermentation.
RESPIRATION:- is ATP generating process in
which molecules are oxidized and the final
electron acceptor is an inorganic molecules.
TYPES OF RESPIRATION :-
Aerobic respiration:- final electron acceptor is Oโ
and occurs in aerobes.
Anaerobic respiration: final electron acceptor is
inorganic moleculeother than Oโ .
18. Krebs cycle or TCA cycle
18
โซIs second phaseof aerobic respiration.
โซCytoplasmic membrane.
โซPyruvate formed enters TCA cycleonlyafterconverted
into acetylCoA by decarboxylation rxn ( transition
phase).
โซStartswith condensaion of acetylCoAand
oxaloacetate.
โซAcetylCoA isoxidized and released as CO2 and
oxaloacetate is regenerated.
20. Contdโฆ
20
โซFrom TCA cycle, oxidation of one acetylCoA
molecule produce 3 NADH , 1 FADHโ and
1 GTP. ( 1 lucose=2 pyruvate= 2 acetylCoA)
โซAll the NADH and FADH2 enters intoelectron
transport chain and finally ATP aregenerated.
21. Electron transport chain
21
โซLast phase of respiration which generates ATP
from reduced substrates.
โซConsists of a sequence of carrier molecules though
which electrons passes.
โซOccurs in plasma membrane ( eukaryotic cell-
inner mitochondrial membrane).
22. Contdโฆ
โซThreeclassesof carrier molecules
1)Flavoprotein :- coenzyme derived from viatmin B2 (riboflavin)
and perform alternating oxidation and reduction reaction.
3)Ubiquinones :- small non protein carriers.
2)Cytochromes :-protein with iron containing group (heme).
22
23. 23
โข Electron transportchain is different in different bacteria ,
even a single bacteria have more than one typeof ETC but
their target is to deriveenergyinthe form of ATP.
Contdโฆ
26. Anaerobic respiration
26
โซFinal electron acceptor is NO3โป , NO2โป, NโO,
SOโโปโป,COโโปโป, etc. and occurs in strict anaeresand
facultative anaerobes.
โซSometimes Pseudomonas sps and Bacillus sps can
use nitrate as final eโป acceptor.
โซATP generationvaries from bacteria to bacteria
and always less than aerobic respiration.
โซAlternative electron carriers are used in the ETC.
28. Fermentation
28
โซUsed by organisms that cannot respire because of
either lack of inorganic electron acceptor or
absenceof ETS.
โซTerminal electron acceptor is always organic
compound.
โซEnd product depends on type of microrganisms.
โซAnalysis of end product isvaluable in identifying
particular bacteria.
โซATP generating pathway is usually glycolysis(
2ATP).
31. Lactic acid fermentation
Santosh Yadav 31
๏Homolactic fermentersuse theglycolytic
pathway and directly reduce almost all their pyruvate
to lactatewith theenzyme lactatedehydrogenase ( eg.
Lactobacillus spp)
๏Heterolactic fermenters form substantial amounts
of products other than lactate; many produce lactate,
ethanol, and CO2( Escherichia coli).
