A multi-bacteriocin cheese starter system comprising nisin and lacticin 3147 in Lactococcus lactis, in combination with plantaricin from Lactobacillus plantarum

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Mills, S.
Griffin, Carmel
O'Connor, P. M.
Serrano, L. M.
Meijer, Wilco C.
Hill, Colin
Ross, R. Paul
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American Society for Microbiology
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Functional starter cultures demonstrating superior technological and food safety properties are advantageous to the food fermentation industry. We evaluated the efficacy of single and double bacteriocin-producing starters of Lactococcus lactis capable of producing the Class I bacteriocins, nisin A and/or lacticin 3147 in terms of starter performance. Single producers were generated by mobilising the conjugative, bacteriophage resistance plasmid pMRC01, encoding lacticin genetic determinants, or the conjugative transposon Tn5276, encoding nisin genetic determinants, to the commercial starter L. lactis CSK2775. The effect of bacteriocin co-production was examined by superimposing pMRC01 into the newly constructed nisin transconjugant. Transconjugants were improved with regard to antimicrobial activity and bacteriophage insensitivity when compared to the recipient strain and the double producer was immune to both bacteriocins. Bacteriocin production in the starter was stable, although the recipient strain proved to be a more efficient acidifier than transconjugant derivatives. Overall, combining Class I bacteriocins (the double-producer or a combination of single producers) proved as effective as individual bacteriocins for controlling Listeria innocua growth in laboratory-scale cheeses. However, using the double producer in combination with the Class II bacteriocin producer Lactobacillus plantarum, or the lacticin producer with the Class II producer, proved most effective for reducing bacterial load. As emergence of bacteriocin tolerance was reduced 10-fold in the presence of nisin and lacticin, we suggest that the double producer in conjunction with the Class II producer could serve as a protective culture providing a food-grade, multi-hurdle approach to control pathogenic growth in a variety of industrial applications. IMPORTANCE: We generated a suite of single and double-bacteriocin producing starter cultures capable of generating the Class I bacteriocins lacticin 3147 or nisin or both bacteriocins simultaneously via conjugation. The transconjugants exhibited improved bacteriophage resistance and antimicrobial activity. The single producers proved as effective as the double-bacteriocin producer at reducing Listeria numbers in laboratory-scale cheese. However, combining the double producer or the lacticin producing starter with a Class II bacteriocin producer, Lactobacillus plantarum LMG P-26358, proved most effective at reducing Listeria numbers, and was significantly better than a combination of the three bacteriocin producing strains, as the double producer is not inhibited by either of the Class I bacteriocins. Since the simultaneous use of lacticin and nisin should reduce the emergence of bacteriocin tolerant derivatives this study suggests that a protective starter system produced by bacteriocin stacking is a worthwhile multi-hurdle approach for food safety applications.
Functional starter culture , Food fermentation , Lactococcus lactis , Lactobacillus plantarum
Mills, S., Griffin, C., O'Connor, P. M., Serrano, L. M., Meijer, W. C., Hill, C. and Ross, R. P. (2017) 'A Multi-Bacteriocin Cheese Starter System comprising Nisin and Lacticin 3147 in Lactococcus lactis, in Combination with Plantaricin from Lactobacillus plantarum', Applied and Environmental Microbiology, 83(14), e00799-17 (17pp). doi:10.1128/aem.00799-17
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