@article{mbs:/content/journal/micro/10.1099/00221287-145-11-3185, author = "Wouters, Jeroen A. and Jeynov, Boyan and Rombouts, Frank M. and de Vos, Willem M. and Kuipers, Oscar P. and Abee, Tjakko", title = "Analysis of the role of 7 kDa cold-shock proteins of Lactococcus lactis MG1363 in cryoprotection", journal= "Microbiology", year = "1999", volume = "145", number = "11", pages = "3185-3194", doi = "https://doi.org/10.1099/00221287-145-11-3185", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-145-11-3185", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "low-temperature adaptation", keywords = "CSP, cold-shock protein", keywords = "LAB, lactic acid bacteria", keywords = "cold-shock proteins", keywords = "cryoprotection", keywords = "2D-EF, two-dimensional gel electrophoresis", keywords = "Lactococcus lactis", abstract = "Low-temperature adaptation and cryoprotection were studied in the lactic acid bacterium Lactococcus lactis MG1363. An approximately 100-fold increased survival after freezing was observed when cells were shocked to 10 °C for 4 h compared to mid-exponential-phase cells grown at 30 °C, indicating an active protection against freezing. Using two-dimensional gel electrophoresis a group of 7 kDa cold-induced proteins (CSPs) was identified that corresponds to a previously described family of csp genes of L. lactis MG1363 (Wouters et al., 1998 R32 , Microbiology 144, 2885–2893). The 7 kDa CSPs appeared to be the most strongly induced proteins upon cold shock to 10 °C. Northern blotting and two-dimensional gel electrophoresis showed that the csp genes were maximally expressed at 10 °C, while induction was lower at 20 and 4 °C. However, pre-incubation at 20 and 4 °C, as well as stationary-phase conditions, also induced cryoprotection (approx. 30-, 130- and 20-fold, respectively, compared to 30 °C mid-exponential phase). For all treatments leading to an increased freeze survival (exposure to 4, 10 and 20 °C and stationary-phase conditions), increased levels of three proteins (26, 43 and 45 kDa) were observed for which a role in cryoprotection might be suggested. Increased freeze survival coincides with increased CSP expression, except for stationary-phase conditions. However, the level of observed freeze protection does not directly correlate with the csp gene expression levels. In addition, for the first time specific overproduction of a CSP in relation to freeze survival was studied. This revealed that L. lactis cells overproducing CspD at 30 °C show a 2–10-fold increased survival after freezing compared to control cells. This indicates that the 7 kDa cold-shock protein CspD may enhance the survival capacity after freezing but that other factors supply additional cryoprotection.", }