AUTHOR=van Gijtenbeek Lieke A. , Eckhardt Thomas H. , Herrera-Domínguez Lucía , Brockmann Elke , Jensen Kristian , Geppel Asger , Nielsen Kristian Fog , Vindeloev Jannik , Neves Ana Rute , Oregaard Gunnar 

TITLE=Gene-Trait Matching and Prevalence of Nisin Tolerance Systems in Lactococus lactis

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.622835

DOI=10.3389/fbioe.2021.622835

ISSN=2296-4185

ABSTRACT=<p><italic>Lactococcus lactis</italic> cheese starter cultures typically contain a mix of many strains and may include variants that produce and/or tolerate the antimicrobial bacteriocin nisin. Nisin is well-established as an effective agent against several undesirable Gram-positive bacteria in cheese and various other foods. In the current study, we have examined the effect of nisin on 710 individual <italic>L. lactis</italic> strains during milk fermentations. Changes in milk acidification profiles with and without nisin exposure, ranging from unaltered acidification to loss of acidification, could be largely explained by the type(s) and variants of nisin immunity and nisin degradation genes present, but surprisingly, also by genotypic lineage (<italic>L. lactis</italic> ssp. <italic>cremoris</italic> vs. ssp. <italic>lactis</italic>). Importantly, we identify that nisin degradation by NSR is frequent among <italic>L. lactis</italic> and therefore likely the main mechanism by which dairy-associated <italic>L. lactis</italic> strains tolerate nisin. Insights from this study on the strain-specific effect of nisin tolerance and degradation during milk acidification is expected to aid in the design of nisin-compatible cheese starter cultures.</p>