Transferibilidad de DNA en Lactobacillus: ¿hay riesgo de transferencia horizontal desde la microbiota a probióticos y viceversa?

ALLIEVI MARIANA CLAUDIA; PALOMINO MARÍA MERCEDES; RUZAL SANDRA MÓNICA; FINA MARTIN JOAQUINA; RUZAL SANDRA MÓNICA; FINA MARTIN JOAQUINA; SANCHEZ RIVAS CARMEN; SANCHEZ RIVAS CARMEN; ALLIEVI MARIANA CLAUDIA; PALOMINO MARÍA MERCEDES

QUíMICA VIVA

DEPARTAMENTO DE QUÍMICA BIOLÓGICA, FACULTAD DE CIENCIAS EXACTAS Y NATURALES, UNIVERSIDAD DE BUENOS AIRES

Año: 2017 vol. 16

1666-7948

In order to determine the capacity of the probiotic strain Lactobacillus casei BL23 to acquire virulence or antibiotic resistance genes from its environment, the comX gene present in this strain (alternative sigma factor of the RNA polymerase P_001986877.1, Gene ID: 6404650), was examined in competence and transformation experiments. In a first approach the presence and transcription activity was determined in conditions known to induce competence in other bacteria (heat, UV irradiation or starvation) and in those present in the intestinal tract (saline stress, acidic pH, presence of bile salts). Messenger RNA of comX gene, was analyzed by Dot Blot and qPCR and related to their expression in early stationary phase growth condition and to the housekeeping gene 16S rRNA. The results showed an increase in the expression of comX in the condition of UV and acid pH with bile salts. The transfer of an antibiotic resistance marker (CmR), present in a replicative plasmid, was determined in all these conditions by evaluating the most probable number (MPN). In all the conditions assayed, the number of transformants was not significantly different from control in non-induced condition and from the mutation frequency. Although an induction of expression of comX was observed it was not enough to supply competence for plasmid or chromosomal transformation. These results argue in favor of the absence of transformability of Lactobacilli although it is not sufficient to ensure the total absence of transfer mechanisms in these bacteria. Discussion is focused on the recombining capacity of this strain, the presence prophages, and the role of SOS and CRISPR-cas functions.