Changes in protein synthesis during thermal adaptation of Propionibacterium freudenreichii subsp. shermanii.
Dairy propionibacteria are present in Graviera Kritis, a traditional Gruyère-type cheese made without added propionic starter. Ten isolated strains were identified by a combination of SDS-PAGE, species-specific PCR and according to their ability to ferment lactose. They were all found to belong to the Propionibacterium freudenreichii subsp. shermanii species. Because of the stressing Gruyère technology, which includes cooking at 52 to 53 degrees C their thermotolerance was investigated at 55 degrees C. Thermotolerant and thermosensitive strains were clearly discriminated. Interestingly, the reference strain CIP 103027 belongs to the sensitive subset. One sensitive strain, ACA-DC 1305 and one tolerant, ACA-DC 1451, were selected for further study and compared to CIP 103027. For the sensitive strains ACA-DC 1305 and CIP 103027, heat pre-treatment at 42 degrees C conferred thermoprotection of cells at the lethal temperature of 55 degrees C, while there was less effect on the tolerant ACA-DC 1451. No cross-protection of salt-adapted cells against heat stress was observed for none of the strains. Differential proteomic analysis revealed distinct but overlapping cell responses to heat stress between sensitive and tolerant strains. Thermal adaptation upregulated typical HSPs involved in protein repair or turnover in the sensitive one. In the tolerant one, a distinct subset of proteins was overexpressed, whatever the temperature used, in addition to HSPs. This included enzymes involved in propionic fermentation, amino acid metabolism, oxidative stress remediation and nucleotide phosphorylation. These results bring new insights into thermoprotection in propionibacteria and the occurrence of divergent phenotypes within a same subspecies.
Laboratory of Dairy Research, Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
Rania
R
Anastasiou
Pauline
P
Leverrier
Ioannis
I
Krestas
Annette
A
Rouault
George
G
Kalantzopoulos
Patrick
P
Boyaval
Effie
E
Tsakalidou
Gwénaël
G
Jan
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001483:Base Sequence; D002611:Cheese / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005285:Fermentation; D005516:Food Microbiology; D006360:Heat-Shock Proteins / Q000032:analysis; D006358:Hot Temperature; D007785:Lactose / Q000378:metabolism; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D019936:Probiotics; D011424:Propionibacterium / Q000145:classification / Q000378:metabolism / Q000502:physiology*; D013045:Species Specificity
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; D007785:Lactose