TY - JOUR
T1 - Diversity in NaCl tolerance of Lactococcus lactis strains from DL-starter cultures for production of semi-hard cheeses
AU - Kristensen, Lise Søndergaard
AU - Siegumfeldt, Henrik
AU - Larsen, Nadja
AU - Jespersen, Lene
PY - 2020
Y1 - 2020
N2 - Mesophilic starter cultures, such as Lactococcus lactis, are exposed to NaCl stress during brining of cheeses influencing their viability. We investigated the effect of NaCl water solutions, used at concentrations of 3.4%, 8.0% and 15% (w/v), on viability of Lc. lactis subsp. cremoris, Lc. lactis subsp. lactis biovar. diacetylactis and Lc. lactis subsp. lactis isolated from commercial DL-starter cultures. Viability was assessed by plate counts and flow cytometry. Bacterial viability decreased with increased concentration of NaCl in a strain-dependent manner (between 0.02% and 62% cfu at 15% (w/v) NaCl, compared with controls at 0.85% (w/v) NaCl), whereas no significant differences were detected between the subspecies. Viability levels determined by plate counts were generally lower than by flow cytometry, indicating the presence of viable but not culturable cells. Knowledge of salt tolerance of Lc. lactis strains would enable rational selection of starter cultures targeting production of cheeses with different NaCl content.
AB - Mesophilic starter cultures, such as Lactococcus lactis, are exposed to NaCl stress during brining of cheeses influencing their viability. We investigated the effect of NaCl water solutions, used at concentrations of 3.4%, 8.0% and 15% (w/v), on viability of Lc. lactis subsp. cremoris, Lc. lactis subsp. lactis biovar. diacetylactis and Lc. lactis subsp. lactis isolated from commercial DL-starter cultures. Viability was assessed by plate counts and flow cytometry. Bacterial viability decreased with increased concentration of NaCl in a strain-dependent manner (between 0.02% and 62% cfu at 15% (w/v) NaCl, compared with controls at 0.85% (w/v) NaCl), whereas no significant differences were detected between the subspecies. Viability levels determined by plate counts were generally lower than by flow cytometry, indicating the presence of viable but not culturable cells. Knowledge of salt tolerance of Lc. lactis strains would enable rational selection of starter cultures targeting production of cheeses with different NaCl content.
U2 - 10.1016/j.idairyj.2020.104673
DO - 10.1016/j.idairyj.2020.104673
M3 - Journal article
AN - SCOPUS:85080056113
VL - 105
JO - International Dairy Journal
JF - International Dairy Journal
SN - 0958-6946
M1 - 104673
ER -