Bacteriosinas

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BACTERIOCINS: DEVELOPING INNATE IMMUNITY FOR FOOD
Paul D. Cotter*, Colin Hill* and R. Paul Ross‡
Abstract | Bacteriocins are bacterially produced antimicrobial peptides with narrow or broad host ranges. Many bacteriocins are produced by food-grade lactic acid bacteria, a phenomenon which offers food scientists the possibility of directing or preventing the development of specificbacterial species in food. This can be particularly useful in preservation or food safety applications, but also has implications for the development of desirable flora in fermented food. In this sense, bacteriocins can be used to confer a rudimentary form of innate immunity to foodstuffs, helping processors extend their control over the food flora long after manufacture.
F O O D M I C RO B I O LO GY
BACTERIOCINS

Bacterially produced, small, heat-stable peptides that are active against other bacteria and to which the producer has a specific immunity mechanism. Bacteriocins can have a narrow or broad target spectrum.

Alimentary Pharmabiotic Centre, *Microbiology Department, University College Cork, Cork, Ireland. ‡ Moorepark Biotechnology Centre, Teagasc, Cork, Ireland. Correspondenceto C.H. e-mail: c.hill@ucc.ie
doi:10.1038/nrmicro1240

Perhaps the oldest and most widespread antimicrobial strategy in living systems is the use of antimicrobial peptides by the innate immune systems of many forms of life, from insects to plants to humans. Antimicrobial peptides can be fast acting and have broad-spectrum activity, which diminishes the possibility of resistance developing intarget species. One example of antimicrobial peptides are the defensins, such as the α-defensins, which are produced by neutrophils in the small intestine and which act to reinforce the physical barriers of the mucosal surface. However, the production of antimicrobial peptides is not confined to multicellular organisms. BACTERIOCINS are ribosomally synthesized antimicrobial peptides produced by onebacterium that are active against other bacteria, either in the same species (narrow spectrum), or across genera (broad spectrum) and, as with host defence peptides1, cell signalling mechanisms can also be involved. Producer organisms are immune to their own bacteriocin(s), a property that is mediated by specific immunity proteins. It has been suggested that between 30–99% of the Bacteria andArchaea make at least one bacteriocin2,3, although genome analyses should ultimately provide a more definitive figure4,5. Many bacteriocins are produced by food-grade lactic acid bacteria (LAB), and this offers the possibility of manipulating food microbial ecosystems in a deliberate fashion — for

example, by using bacteriocins to protect food against contamination with, or prevent the growth of,specific pathogenic bacteria. Alternatively, narrow-host-range bacteriocins can be used to influence a microbial population in a specific ecosystem towards a particular outcome in which a desirable strain predominates (competitive exclusion). In this sense, bacteriocins can potentially be used as a form of innate immunity in food to augment physical, physiological (for example, pH) and chemicalpreservatives, and to influence the probable final population in complex food systems. The first description of bacteriocin-mediated inhibition was reported 80 years ago, when antagonism between strains of Escherichia coli was first discovered6. Originally called ‘colicins’, to reflect the original producer organism, gene-encoded antimicrobial peptides produced by bacteria are now referred to as‘bacteriocins’. Although the deliberate use of bacteriocins as preservatives in food was formally proposed in 1951 REF. 7 , it is likely that mankind has benefited from the serendipitous production of bacteriocins in food in the 8,000 years since cheese and other fermented foods were first manufactured. Many studies have revealed that the LAB used in cheese manufacture to convert lactose to lactic...