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Bacteriocins
The document discusses bacteriocins, ribosomally-synthesized proteins produced by bacteria, highlighting their classification, mode of action, and role in food preservation. Bacteriocins are gaining attention as natural preservatives due to their efficacy, safety, and growing public awareness regarding chemical additives. It details various applications in food industries, agriculture, and pharmaceuticals, emphasizing their health benefits and effectiveness against pathogenic bacteria.
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Bacteriocins
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- 2. Introduction Classification Mode of Action Isolation of Bacteriocins Assays for Detection of Bacteriocins Role in Food Preservation Advantages Applications
- 3. Definition: Bacteriocinsare ribosomally-synthesised toxic proteins produced by bacterial strains which are not lethal to the producing strain. Bacteriocins are the secondary metabolites synthesized by bacterial strains during their stationary phase of growth. In 1925, the first bacteriocin, called Colicin was originally identified as an antimicrobial protein produced by E.coli.
- 4. India hasvarious traditional food patterns varying from Northern cuisine involving Roti, pickled fruits and vegetables to the Southern Cuisine which is best known for spicy-hot blends, fresh pickles, coconut milk and so on. Fig. 01: Northern Cuisine Fig. 02: Southern Cuisine
- 5. Class I ClassII Class III Class IV Bacteriocins
- 6. Class I- the lantibiotics Class II - the small heat stable non lantibiotics/unmodified peptides Class III - large heat labile proteins Class IV - complex peptides carrying lipid or carbohydrate moieties. The classification scheme for gram negative bacteria includes modified proteins, non-lantibiotic heat stable bacteriocins, colicins and microcins. Colicins and Microcins are compounds produced by bacteria belonging to the family Enterobacteriaceae and distinguished based on their size.
- 7. Most ofthe bacteriocins destroy the energy potential of sensitive cells, by forming membrane channels or pores. The best described mechanism is pore formation. Fig. 03: Mechanism of Pore Formation
- 8. Fig. 04: Modeof Action
- 9. Collect the MILKPRODUCTS Make the appropriate dilutions Incubate aerobically on de Mann Rogosa Sharpe (MRS) agar Isolate the bacteriocins producing bacteria using pour plate technique transfer colonies to the MRS broth, obtain the supernatant by centrifugation Obtain the precipitates containing bacteriocins Fig. 05: Milk products
- 10. Dilute the APPAMBATTER with saline and plate on MRS agar Incubate an-aerobically and obtain the colonies Transfer to MRS broth Obtain the supernatant by centrifugation Sterilize by passing through filter membrane Bacteriocins Fig. 06: Appam batter
- 12. Bacteriocins candiffuse in solid or semisolid culture media. Making use of this fact, scientist conducted the experiment on detection of bacteriocins using agar in 1970. Scientists utilized the ELISA for detection of the bacteriocins. They used affinity-purified anti-nisin immunoglobulin for the binding of nisin and anti-nisin peroxidase as the enzyme to be linked with the substrate. The activity of bound enzyme was determined which implied the amount of bacteriocins.
- 13. There isa continuous raise of awareness in the public regarding the amount of chemical intake by their body as food preservatives. In view of the above problem, bio-preservatives are in very high commercial demand at the present, in the form of protective cultures or their metabolites i.e. enzymes and bacteriocins. As there is an increase in demand for natural, minimal processed, micro-biologically safe products, bacteriocins provide the consumers with high health benefit.
- 14. The bacteriocinsfrom food grade Lactic Acid Bacteria (LAB) qualify as an ideal food bio preservative primarily because: i. It is proven non-toxic to humans. i. Does not alter the nutritional properties of the food product. ii. Effective at low concentration. i. Active under refrigerated storage. Fig. 07: Lactic Acid Bacteria
- 15. Bacteriocin Pathogenic bacteria Food system NisinClostridium botulinum, Listeria monocytogens Cheese, Camembert, Ricotta cheese, Manchego cheese Pediocin ACH Listeria monocytogens, S.aureus, E. coli- 0157:H7 Milk and Cheddar cheese Enterocin AS-48 Enterocin AB, Enterocin A, Pediocin ACH Listeria monocytogens Meat Enterocin AS-48 B. cereus Rice, vegetables Table 01: Various bacteriocins in food systems
- 16. Advantages: i. Saferpreservatives than chemicals. i. More accurate efficacy. i. Good acceptance from consumers. i. To overcome various drawbacks such as toxicity of chemicals and nutritional alteration of food.
- 17. Applications: • Inhibitionof pathogenic bacteria. • Natural preservatives in food industries. • Agricultural applications – in disease control. • Pharmaceutical applications. a. Lantibiotics – treat inflammation, allergies, skin infections, peptic ulcers, etc. b. Colicins – treat Haemorrhagic colitis and haemolytic uremic syndrome. c. Microcins – treat Salmonellosis.