GENOMIC DIVERSITY OF PHAGES INFECTING PROBIOTIC STRAINS OF Lactobacillus paracasei

MERCANTI, DIEGO JAVIER; ROUSSEAU, GENEVIÈVE M; CAPRA, MARÍA LUJÁN; QUIBERONI, ANDREA DEL LUJÁN; TREMBLAY, DENISE M; LABRIE, SIMON J; MOINEAU, SYLVAIN

APPLIED AND ENVIRONMENTAL MICROBIOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2016 vol. 82 p. 95 - 105

0099-2240

Strainsof the Lactobacillus casei group have been extensivelystudied because some of them are used as probiotics in foods. Conversely, theirphages have received less attention. Here we analyze the complete genomesequence of L. paracasei temperatephages CL1, CL2, iLp84,iLp1308 and iA2. Only phage iA2 couldnot be replicated on an indicator strain. Genome length varied from 34,155 bp(iA2) to 39,474 bp (CL1). Phage iA2 and iLp1308 (34,176 bp) possess the smallest genomes reported so far forphages of the L. casei group. TheirGC content ranged from 44.8% to 45.6%. As observed with many other phages,their genome was organized as follows: genes coding for DNA packaging ?morphogenesis ? lysis ? integration ? genetic switch ? replication. Phages CL1,CL2 and iLp1308 have a highidentity to each other. Phage iLp84was also related to these three phages but it was limited to gene productsinvolved in DNA packaging and some structural proteins. Genomic fragments ofphages CL1, CL2, iLp1308and iLp84 were found in severalgenomes of other L. casei strains.Prophage iA2 is unrelated to these four phages but almost all its genome wasfound in at least four L. caseistrains. Overall, these phages are distinct from the previously characterized Lactobacillus phages. Our resultshighlight the diversity of L. caseiphages and indicate frequent DNA exchanges between phages and their hosts.