[i]Propionibacterium[/i] genomics to decipher remarkable phenotypic biodiversity of strains and adaptation to substrates and environments
Résumé
The genus Propionibacterium belongs to the class of Actinobacteria (Gram +, high GC content).
They are non-spore-forming, microaerophylic pleomorphic rods. They possess 2.5-3 Mb circular
chromosome. They synthetise propionate and acetate as main metabolites, are able to grow without
amino acid addition and survive to stationary phase. Up to now, seventeen species have been
sequenced. Several complete genomes are available for P. acnes, P. freudenreichii, P. avidum and P.
acidipropionici species.
Among human species, comparative genomics pointed out (i) genes responsible for
exopolysaccharide production in P. avidum and (ii) camp genes involved in P. acnes hemolytic
activity. At infraspecific level, comparison of P. acnes genomes revealed pathogenicity island,
comparison of P. freudenreichii revealed genetic basis (genomic islands, major gene or mutations)
responsible for sugar degradation, lipolytic and anti-inflammatory activities. Transcriptomics
deciphered adaptation of P. acnes and P. freudenreichii to growth phases and different environments
(cold, colonic conditions) in pure culture.
At community level, metagenomics highlights a peculiar structure of P. acnes population, and
strains specific to acneic skins. In the next few years, the impact of environment, and bacterial
interactions have to be taken into account for a deep investigation of Propionibacterium
fonctionality at ecosystem level.