The document discusses the roles of microorganisms in producing primary and secondary metabolites that are crucial for various ecological and industrial applications. It explains fermentation processes, metabolism, and the types of metabolites, highlighting the differences between primary metabolites essential for growth and secondary metabolites that serve ecological functions. Specific examples of metabolites such as amino acids, vitamins, organic acids, and enzymes are provided, emphasizing their importance in food technology and industry.

1. PRIMARY AND SECONDARY
METABOLITES PRODUCED BY
MICROORGANISMS.
Chirantan Sandip Saigaonkar
FTS/2020/41
Shramshakti college of food technology, Maldad
chirantansaigaonkar2032@gmail.com

2. ❑ Introduction
 Microorganisms are of immense importance to environment and essential
to all life forms.
 They also act as sources of nutrients.
 Microorganisms are present in all types of environments of different
climatic and temperature zones.
 They can be used in preparation of variety of foods and as sources of food.

3. ❑ Fermentation
 Fermentation refers to the biological technique in which the growth and metabolic activities
of the microbes (for their survival) are used for the preservation and transformation of food
products.
 Metabolites synthesized during fermentation, inhibit the spoilage and pathogenic organisms
in food its extending their shelf life (Terefe, 2016).
 Biochemical reactions that extract energy and form products in anaerobic conditions
 Different bacteria and fungi are mainly used for fermentation.
 The term, “industrial fermentation” is used in context to the intentional use of fermentation
for large scale production of microbial biomass or metabolites.
 Genetically engineered microbes are employed in industrial fermentation for rapid
production of metabolites.

4. ❑ Metabolism and metabolites
 Metabolism : In simple metabolism is a series of chemical reactions occurring in of cellular
organisms, and are essential for their living. They are performed by either releasing or
consuming energy and accomplished in two steps as mentioned;
Metabolism = anabolism + catabolism
Anabolism: reactions which lead to formation of more complex compounds (consume
energy).
Catabolism: reactions that cause breakdown of complex (large) compounds to simpler (small)
compounds (release energy).
Intermediates: compounds involved in metabolism.
End Products: final products

5.  Metabolites : comprised of end products of metabolic processes, and
intermediate products formed during them.
 Types of metabolites :
1) Primary metabolites
2) Secondary metabolites
Characteristics of
Primary Metabolites Secondary Metabolites
• Synthesized during exponential
growth phase (trophophase).
• Maintain normal physiological
process, hence also known as
central metabolites.
• Metabolic activities continue, but
the product formation is ceased.
• Involved in growth, development
and reproduction.
• Non toxic.
• Produced when organisms
complete logarithmic growth
phase and enter stationary phase
(idiophase).
• Not necessary for the normal
growth, but are important for their
defense and protective
mechanisms.
• Are synthesized for a definite
period by the cells.
• Some of these may be toxic.

6. ❑ Primary Metabolites
 Primary metabolism is same in all organisms and also its products.
 It is concerned with the release of energy and important macromolecules like proteins,
nucleic acids and other cellular constituents are synthesized as their consequence.
 They are important in growth and reproduction of the organisms. And the organisms may die
as a result of lack of these metabolites.
 Primary catabolic products: ethanol, lactic acids, butanol, etc.
 Primary anabolic products: amino acids, enzymes, nucleic acids, etc.

7. ❑ Secondary Metabolites
• Secondary metabolites have no direct involvement in the growth related functions of the
organisms.
• Instead they perform ecological roles like pollinator attractants, chemical defense against
microorganisms, insects, and other predators.
• Produced in small quantities as compared to primary metabolites.
• Their production is influenced by environmental factors.
• Some of these can be specific to certain organisms.
• Secondary metabolites include pigments, antibiotics, enzyme inhibitors etc.
Secondary metabolites are synthesized late in growth cycle during
stationary phase, hence, they are of less or no use to the organisms.

8. Primary Metabolites (Demain) Secondary Metabolites
Amino acids
(Glu, Lys, Thr)
Pigments
Protein
(Single Cell Protein)
Phenolic compounds
Vitamins
(riboflavin-B2, cyanocobalamin-B12)
Flavonoids
Carbohydrates/sugars
(Fructose, sorbose)
Alkaloids
Organic acids
(Acetic acid, propionic acid, succinic
acid, citric acid, etc.)
Mycotoxins

9. ❖ Amino acids
⮚Building blocks of protein molecules, hence used as dietary and feed supplements for human
and animals respectively.
⮚Two types: non-essential (synthesized in body) and essential (not synthesized in body, hence
required to be supplemented externally), both are required for protein synthesis.
⮚ Production of essential microorganisms using microbial fermentation and enzymatic process
is considered beneficial, being capable of producing pure products in cost effective and
ecologically acceptable manner.
⮚ Corynebacterium glutamicum and Escherichia coli are used in commercial production of L-
glutamic acid (MSG), L-aspartic acid, L-Lys, L-Met, L-Phe, L-Try, etc using fermentation
and enzymatic transformation methods.
⮚ L-Glutamate is used as flavour enhancer in beverages and food industries.
⮚ Amino acids like Met, Lys, Try, Thr find applications as animal feed additives due to the
increase in demand for meat and poultry products (for faster growth and weight).
Function Examples
Animal feed
additives
Lys, Met, Thr
Flavour
enhancers
Aspartic acid, MSG,
Ser
Antioxidants Cys, L-Try, L-His
Sweetners Aspartame (made
from Aspartic acid),
Phe

10. ❖ Vitamins
 Micronutrients required in trace amounts produced during regular metabolism of
microorganisms and widely used as food additives, health supplements, and therapeutic
agent etc.
• Vitamins like riboflavin (B2) produced by chemical synthesis, are generally used for
pharmaceutical and food applications, and those by fermentation are used in animal feeds.
• Vitamins are either produced by:
1. Direct fermentation
2. Combination of chemical and microbiological processes
• Vitamin B12 (cyanocobalamin) is another vitamin synthesized by fermentation methods.
• Industrial production of these vitamin is achieved by using Propionibacterium shermanii and
Pseudomonas dentrificans.

11. ❖ Organic acids
(Demain)
• Commercial production of organic acids is done using filamentous fungi.
• Citric acid is most commonly produced organic acid by industrial fermentation and is
synthesized using A. niger or its mutant/s
• Koji fermentation process, liquid culture shallow pan process, and the submerged
fermentation process are used for citric acid production.
• Citric acid is commonly used in food products as an acidulant, flavour enhancer, and
antioxidant.
• Acetic acid also called as vinegar is also synthesized microbially using strains of Acetobacter

12. ❖ Enzymes
(Singh)
• Proteins produced as primary metabolites by different organisms, and
catalyze various metabolic pathways.
• Their absence may increase the time required for completion of the
biological reactions.
• In food industries the catalytic activities of enzymes have been used for
production of products like bread, wine, beer, etc
• Enzymes synthesized by this method are cost-effective, easy to produce
and biodegradable.
Source Function
Lipase A. niger, A. flavus Faster cheese ripening,
Dough stability and conditioning in
bakeing
Protease Pseudomonas sp., B. subtilis,
Serratia sp., etc
Restrict haze formation in beverages
Amylase B. subtilism, B. licheniform,
etc
Flour adjustment, bread softening in
baking
Treatment of barley feed for poultry
and calf.

13. ❖ Alcohol
• Ethanol is a primary metabolite and used as a biofuel.
• It as used in different applications like solvent for dyes and waxes, cosmetics, disinfectant,
etc. recombinant microorganisms like E. coli, Clostirdium thermocellum, etc. are used in
microbial fermentation for production of ethanol using different carbon sources.
• Glycerol used in various applications like foods and beverages, cosmetics, pharmaceuticals,
etc. is also produced using fermentation by osmotolerant yeast Candida glycerinogenes

14. ❖ Pigments)
• Secondary metabolites produced by organisms like plants and bacteria that produce various
colours for different purposes.
• They may find applications in biological as well as industrial applications.
• Non-toxic and may perform medicinal functions like antioxidants, additives etc.
• Bacterial pigments are easier for extraction and there is no lack of raw material, and
dependency up on season for their production.

15. ❖ Flavonoids
• Secondary metabolites found in many fruits and vegetables.
• They also are phytonutrients (plant nutrients), and some of them also provide coloration to
the organisms.
• Largest group of phytonutrients in plants (about 6000 known).
• Antioxidants with anti-inflammatory and immune system benefits.
• Include antimicrobials, photoreceptors, visual attractors, etc.
• Flavonoids may play critical roles as signaling molecules in mammals, through their ability
to interact with a wide range of protein kinases.
• Subclass of flavonoids include; Flavones, Flavonols, Anthocyanidin, Chalcones, Isoflavones,
etc.
• Examples; Naringenin, Hesperidin, Myrecitin, Apigenin, etc.

16. ❖ Phenolic Compounds
• Characterized by presence of one or more aromatic rings having a hydroxyl functional group,
most synthesized from phenyalanine.
• Salicyclic acid- simple phenolic compound, defence against pathogens.
• Aspirin- derivative of salicyclic acid, reduces inflammation, pain, and fever in humans.
• Isoflavones- rapidly produced in plants of legume family, when attacked by bacteria and
fungal pathogens.
• Anthocyanins and anthocyanidins- function as attractants, give pink and purple colour to
fruits and flowers. Attract insects and pollinators to perform pollination and fruits dispersal.

17. ❖ Aflatoxins
• Large group of N- containing compounds. Derived from primary metabolites like amino acids.
• Stored in plant organs like leaves or fruits and transferred to animals and humans when they
consume plant parts.
• Many of them are toxic to mammals, since they act as nerve poisons, enzyme inhibitors, and
membrane transfer inhibitors.
• Their bitter and bad taste help animals to avoid eating such plants.
• Morphine, codeine and cocaine- work as painkillers.
• Atropine- medicinal alkaloid used in anaethesia
• Vincristine and vinblastine- inhibit cell division, hence used in treating blood and lymphatic
cancer.
• Quinine is poisonous, and kills Plasmodium (malaria causing parasite).

18. ❖ Mycotoxins

19. References
 Terefe, N. S. (2016). Food fermentation.
 Demain, A. L. (1980). Microbial production of primary metabolites. Naturwissenschaften, 67(12), 582-587.
 https://microbenotes.com/primary-vs-secondary-metabolites/
 Singh, R., Kumar, M., Mittal, A., & Mehta, P. K. (2017). Microbial metabolites in nutrition, healthcare and agriculture. 3
Biotech, 7(1), 15.