Influence of cooling temperature and duration on cold adaptation of Lactobacillus acidophilus RD758.
The effect of different cooling temperatures and durations on resistance to freezing and to frozen storage at -20 degrees C in Lactobacillus acidophilus RD758 was studied, by using a central composite rotatable design. A cold adaptation was observed when the cells were maintained at moderate temperature (26 degrees C) for a long time (8h) before being cooled to the final temperature of 15 degrees C. These conditions led to a low rate of loss in acidification activity during frozen storage (0.64 minday(-1)) and a high residual acidification activity after 180 days of frozen storage (1011 min). The experimental design allowed us to determine optimal cooling conditions, which were established at 28 degrees C during 8h. Adaptation to cold temperatures was related to an increase in the unsaturated to saturated fatty acid ratio and in the relative cycC19:0 fatty acid concentration. Moreover, an increased synthesis of four specific proteins was observed as an adaptive response to the optimal cooling conditions. They included the stress protein ATP-dependent ClpP and two cold induced proteins: pyruvate kinase and a putative glycoprotein endopeptidase.
Wang
Yu
Y
UMR Génie et Microbiologie des Procédés Alimentaires, INA P-G, INRA, 78850 Thiverval-Grignon, France.
Delettre
Jérôme
J
Guillot
Alain
A
Corrieu
Georges
G
Béal
Catherine
C
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002849:Chromatography, Gas; D003080:Cold Temperature; D015925:Cryopreservation; D015180:Electrophoresis, Gel, Two-Dimensional; D010450:Endopeptidases / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D007779:Lactobacillus acidophilus / Q000502:physiology*; D020543:Proteome; D011770:Pyruvate Kinase / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors
D001426:Bacterial Proteins; D005227:Fatty Acids; D020543:Proteome; D011770:Pyruvate Kinase; D010450:Endopeptidases; C119658:ClpP2 protein, bacteria; D012697:Serine Endopeptidases