The document discusses metabolism in cells and organisms. It describes primary metabolism, which includes common enzyme-catalyzed reactions essential for growth. Secondary metabolism produces diverse, often species-specific compounds that provide ecological advantages but are not essential for growth. Fermentation is defined as a type of anaerobic respiration where organic molecules serve as the terminal electron acceptor, resulting in products like alcohols and acids.

1. Lec-2
Dr. Imran Sajid

2. The metabolism
• It includes all enzyme-catalyzed reactions of a cell
• Can be divided into two categories Primary
metabolism and secondary metabolism
• Primary metabolic pathways are generally common
to all organisms and may be
• Anabolic changes (the energy consuming processes)
• Catabolic changes (the energy generating processes)
• Products of primary metabolism that have industrial
importance include: alcohols, amino acids, organic
acids, nucleotides, enzymes and microbial cell mass

3. Secondary metabolites
Secondary Metabolism
• Metabolic pathways that are not used during rapid
growth
• It produces diverse often species-specific end
products, most of them are industrially important
including
• antibiotics, Alkaloids, toxins, pigments, enzymes etc
• Secondary metabolite may have certain ecological
advantage for the producer organism but not
necessarily always

4. Bu’Lock 1961
Borrowed the term secondary metabolism from
plant physiology and applied it to microbiology

5. • Formed by only a few organisms
• Seemingly not essential for growth and reproduction
• Formation is extremely dependent on environmental
conditions
• Produced as closely related structures e.g. 32
different anthracyclines from one Streptomyces
• Some times produced as variety of different classes
• Regulation differs significantly from that of primary
metabolites

6. Role of secondary metabolites
There are several hypothesis
Hans Zahner’s illustration
Morphogenesis
Differentiation
Transport
Regulation
Intermediary metabolism
Secondary
metabolism

7. Role of secondary metabolites
• Playing field for the evolution of further biochemical
developments.
• These developments can proceed with out damaging
primary metabolism
• Genetic changes may convert a secondary metabolite
into a primary metabolite
• Secondary metabolites may give certain ecological
advantages to the producing strain e.g. antagonistic
activity, degradative ability etc

8. • Biochemical capabilities of microorganism are vast
• Production of new and unusual compounds can be
expected
• Main task of an industrial microbiologist may be
• To develop procedures for obtaining new microbial
metabolites

9. There are five approaches
• Screening (only way to obtain completely new
compounds)
• Chemical modification (chemical synthesis)
• Biotransformation (change by microbial or
enzymatic activity)
• Interspecific protoplast fusion
• Gene cloning

10. Screening
It is an interdisciplinary activity, it combines the
activities of
• Microbiology (isolation and identification, strain
preservation, biological activity and fermentation
practices)
• Chemistry &Biochemistry (analytical procedures,
approaches for purification, synthesis of inhibitors)
• Engineering (technical equipments)
• Bibliographic (literature search)

11. Screening can never be a routine activity…..
Goal is always to identify compounds of commercial
interest
To devise the ways for separating the already known
compounds or the compounds of no commercial
interest (dereplication)
Omura 1986… 42 completely new compounds
(commercially valuable)

12. Screening
There are no universal screening procedures, one has to develop
The capacity of an industrial screening program is
1000-2000 strains per year
Most of the screening programs focus on
• Chemotherapeutically useful compounds e.g. Antibiotics,
• Anticancer compounds (antitumor agents)
• Antiviral compounds
• Enzyme inhibitors

13. Screening
Screening is also done for….
• To select the better starter cultures for food industry
• To select the organisms capable of degrading hazardous and
persistent chemicals
Of the 40,000 antibiotically active compounds 67% are
produced by microbes
• Actinomycetes 85%
• General bacteria 4%
• Fungi 11%

14. Success depends on two factors
• Selection of appropriate strains (30-40% influence)
• Selection of appropriate test systems (60-70%
influence)

15. Selection of appropriate strains
Rare microbial strains from extreme or unusual environments
may be more interesting e.g.
• From high altitude
• From cold habitats (glaciers and poles)
• From sea water (sea trenches)
• Hot water springs (thermophyles)
• Deserts
• From petroleum fields
• Bacteria present in the animal gut e.g. ruminants etc

16. Screening
Selection of appropriate strains
One gram of soil contains
• 106-108 bacteria
• 104-106 actinomycetes spores
• 102- 104 fungal spores
• Less than 1% of the microorganisms have been screened
• About 100,000 fungi are poorly studied
Organisms that may be important source of useful compounds
Bacteria, actinomycetes (streptomyces+ other rare members),
Fungi, endophytes, cyanobacteria, lichens, sponges, plants etc

17. Screening
Isolation and enrichment
• Physical and chemical treatments
• Serial dilution
• Plating on selective media
• Incubation under appropriate culture condsitions
• Antagonistic activity in crowding
• Strain selection and purification
• Culture preservation

18. Enrichment of Microorganisms by selection of
appropriate culture conditions
Type of isolate Enrichment method
Acidophyles Extreme pH values (2-4)
Psychrotrops Low temperature (4-15C)
Thermophiles High temperature (42-100 C)
Norcardia, halophyles High NaCl Concentrations
Anaerobes N2 atmosphere
Losobacter Chitin as growth substrate
Myxobacteria Wood bark, roots
Actinoplanes Pollen grains

19. Success depends on intelligent test
systems by which known or undesirable
compounds can be eliminated
Test systems

20. Screening
Test systems are specific e.g.
• Antibiotics (Agar plates with test strain (zone of inhibition)
• β-lactamase resistant antibiotics (agar plates with β-
lctamases)
• Proteases (agar plates with casein, clear zones)
• Amylases (agar plates with starch, staining with iodine)
• Lipases (agar plates with oil emulsion,precipitation of fatty
acids)
• Phosphatases (agar plates- phenophthalein diphosphate,
color change etc

21. Screening
Omura et al. 1979 (search for inhibitors of cell wall synthesis)
1. Metabolites that inhibited B. subtilus but not Acholiplasma
laidlawii
2. Substances that inhibited the meso-diaminopemelic acid but
not the incorporation of leucine
3. Separation of substances with mol wt more than 1000 as
they may be hazardous
10,000 strains were screened
• A new antibiotic azureomycin was discovered along with six
known antibiotics

22. Sleeping is good for health but not in class

23. What is fermentation???????
• Is it only a physiological process? Yes….No ,
• Is it aerobic respiration? May be ……… but no
• Is it anaerobic respiration? Yes I think so… No-not at
all.
• There was some thing related to terminal electron
acceptor
• I am confused………?????????
• My physiology book should answer it.

24. • Energy is required to carry on life processes
• Energy can be obtained by the oxidation of food
• Important processes involve
Glycolysis
May completes by different routs in different organisms
e.g
• Embden-Meyerhof-Parnas (EMP) pathway
• Pentose phosphate (PP) pathway
• Enter-Doudoroff (ED) pathway
• Yields low amount of energy = 2ATP+ 2NADH

25. • Many bacteria, yeasts, filamentous fungi, algae, and
protozoa use this mechanism for energy generation
• Important intermediates are produced like, citrate,
succinate, malate, etc
• These C4 and C5 intermediates can be utilized for the
biosynthesis of amino acids, purines and pyrimidines
• Net energy yield in this cyclic processes is,
• ATP + 3NADH +FADH2
The formation of ATP up till this level is through
substrate level phosphorylation

26. Aerobic respiration
• Electron Transport chain (ETC)
• Oxidative phosphorylation
• Electrons are transferred to the terminal electron
acceptor i.e Oxygen……. Through electron carriers,
(the oxidation reduction reactions)
• ATP generation here is by chemiosmotic oxidative
phosphorylation
• Whatever the case is ATP is formed and electrons are
transferred to terminal electron acceptor

27. Anaerobic respiration
• When the terminal electron acceptor is other than
oxygen ceretin other inorganic molecule
• These may be
• Nitrates
• Sulphates
• Carbonates etc
• Whatever the case is ATP is formed and electrons are
transferred to terminal electron acceptor

28. Fermentation
• If the terminal electron acceptor is an organic
molecule e.g.
• Pyruate or some derivative like acetaldehyde
• This results in the reduced wastes like alcohols and
acids
• It may be
• Alcoholic fermentation
• Lactic acid fermentation

29. Fermentation

30. Industrial Fermentation
The word fermentation can have stricter definitions,
when speaking of it in industrial fermentation it
more loosely refers to the breakdown of organic
substances and re-assembly into other substances,
Somewhat paradoxically, fermenter culture in
industrial capacity often refers to highly oxygenated
and aerobic growth conditions, whereas
fermentation in the biochemical context is a strictly
anaerobic process

31. • Fermentation may mean:
• Fermentation (biochemistry), the process of energy production in a cell under
anaerobic conditions (without oxygen)
• Ethanol fermentation, a form of anaerobic respiration used primarily by yeasts
when oxygen is not present in sufficient quantity for normal cellular respiration
• Industrial fermentation, the breakdown and re-assembly of biochemicals for
industry, often in aerobic growth conditions
• In food science, fermentation may mean:
• Fermentation (food), the conversion of carbohydrates into alcohols or acids under
anaerobic conditions used for making certain foods
• Fermentation (wine), the process of fermentation commonly used in winemaking
• Brewing, the process of fermentation as used in making beer
• Fermentation (tea), the name used in the tea industry for the aerobic treatment of
tea leaves to break down certain unwanted chemicals and modify others to
develop the flavour of the tea