RT Journal Article SR Electronic(1) A1 Wouters, Jeroen A. A1 Jeynov, Boyan A1 Rombouts, Frank M. A1 de Vos, Willem M. A1 Kuipers, Oscar P. A1 Abee, Tjakko YR 1999 T1 Analysis of the role of 7 kDa cold-shock proteins of Lactococcus lactis MG1363 in cryoprotection JF Microbiology, VO 145 IS 11 SP 3185 OP 3194 DO https://doi.org/10.1099/00221287-145-11-3185 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-145-11-3185