Bacteriocins: Traditional and Modern Application

Bacteriocins are antimicrobial peptides which are released from certain bacterial species. These have the ability to inhibit the growth of other bacteria, usually most effective against those which are closely related. The mode of stopping other bacteria growing usually involves inhibiting cell wall synthesis, depolarisation of the target cells membrane or pore formation of the cell membrane. The vast majority of Bacteriocins used in industries are from Lactic Acid bacteria so are often deemed safe for human consumption.

Traditionally, Bacteriocins are used to stop food spoilage microorganisms from forming. In particular, Nisin is used to stop the growth of Listeria monocytogenes which can be dangerous to pregnant women or individuals who are immunocompromised. Nisin forms a pore in the target cell membrane and is used in the cheese industry to stop heat-resistant spore forming bacteria from growing. By using Bacteriocins in the food industry, they can often increase the shelf life of food products.

Modern applications of Bacteriocins are used to treat pathogenic bacteria. Lacticin 3147 can inhibit the growth of resistant strains of bacteria such as methicillin-resistant Staphylococcus aeureus (MRSA) and penicillin-resistant Pseudomonas.

Bacteriocins are also being used more frequently in the food industry, apart from being a shelf-promoting additive. For example, in Cheddar cheese production, the maturation period is about six months. By adding Bacteriocins in the form of a starter culture, it will degrade the lactate dehydrogenase and proline dipeptide aminopeptidase faster. This cell lysis creates small peptides and amino acids, which creates the flavour development of the cheese. By creating cell lysis earlier on in the cheese production process, it would be more economical to the cheese industry as it would enable them to create cheese of a higher quality on demand.

Bacteriocins can also be used to control the flora of the cheese. By using Bacteriocins, the non-starting lactic acid bacteria can be controlled, and in low fat cheeses can be produced at a higher temperature than the other option which is more costly (cold-ripening). Even though it can control the flora of these non-starting bacteria can also control the flavour of the cheese. By creating a mutant bacterium which is resistant to the bacterium used, the desired flavour could then be developed whilst keeping the flora under control as the mutant bacteria becomes the more dominant bacteria.

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