primary and secondary metabolites produced by microorganisms

Explore the critical roles of primary and secondary metabolites produced by microorganisms in food technology with this comprehensive presentation. Ideal for students, educators, and industry professionals, this course delves into the production, functions, and applications of these metabolites. Topics include the biosynthesis of primary metabolites like amino acids, organic acids, and vitamins essential for microbial growth, and the diverse range of secondary metabolites such as antibiotics, pigments, enzymes, and flavor compounds with significant industrial applications. Understand the impact of these metabolites on food fermentation, preservation, and enhancement, and learn about the latest advancements in microbial biotechnology.

1. PRIMARY AND SECONDARY METABOLITES PRODUCED BY MICROORGANISMS. Chirantan Sandip Saigaonkar FTS/2020/41 Shramshakti college of food technology, Maldad [email protected]

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-B 2 , cyanocobalamin -B 12 ) 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: Direct fermentation 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.