New insights in the molecular biology and physiology of Streptococcus thermophilus revealed by comparative genomics.
Streptococcus thermophilus is a major dairy starter used for the manufacture of yoghurt and cheese. The access to three genome sequences, comparative genomics and multilocus sequencing analyses suggests that this species recently emerged and is still undergoing a process of regressive evolution towards a specialised bacterium for growth in milk. Notably, S. thermophilus has maintained a well-developed nitrogen metabolism whereas its sugar catabolism has been subjected to a high level of degeneracy due to a paucity of carbon sources in milk. Furthermore, while pathogenic streptococci are recognised for a high capacity to expose proteins at their cell surface in order to achieve cell adhesion or to escape the host immune system, S. thermophilus has nearly lost this unique feature as well as many virulence-related functions. Although gene decay is obvious in S. thermophilus genome evolution, numerous small genomic islands, which were probably acquired by horizontal gene transfer, comprise important industrial phenotypic traits such as polysaccharide biosynthesis, bacteriocin production, restriction-modification systems or oxygen tolerance.
Hols
Pascal
P
Unité de Génétique, Institut des Sciences de la Vie, Université catholique de Louvain, 5 Place Croix du Sud, 1348 Louvain-La-Neuve, Belgium. hols@gene.ucl.ac.be
Hancy
Frédéric
F
Fontaine
Laetitia
L
Grossiord
Benoît
B
Prozzi
Deborah
D
Leblond-Bourget
Nathalie
N
Decaris
Bernard
B
Bolotin
Alexander
A
Delorme
Christine
C
Dusko Ehrlich
S
S
Guédon
Eric
E
Monnet
Véronique
V
Renault
Pierre
P
Kleerebezem
Michiel
M
D001426:Bacterial Proteins / Q000235:genetics*; D016680:Genome, Bacterial; D023281:Genomics; D048249:Streptococcus thermophilus / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D037521:Virulence Factors / Q000235:genetics*
D001426:Bacterial Proteins; D037521:Virulence Factors