gene mutation in the teichoic acids alanylation system of results in diminished proliferation in its natural host.

P. Reimundo , A. Menéndez , J. Méndez , D. Pérez-Pascual , R. Navais , E. Gómez , A.F. Braña , J.A. Guijarro

The cluster is involved in the D-alanylation of teichoic acids in gram positive bacteria. In order to determine the role of this alanylation in the physiology and virulence of , a previously isolated ΔTn signature tagged mutagenesis (STM) clone was analyzed. RT-PCR results revealed that genes form an operon. No major differences could be established between the parental and mutant strains with respect to growth rate, autolytic properties, and susceptibility to acid conditions, lysozyme treatment, anionic detergents, or oxidant agents. However, the mutant was more susceptible to nisin than the parental strain, with minimum inhibitory concentration (MIC) values of 8μg/ml and 16μg/ml, respectively. Less proliferation of the mutant was observed in competence index experiments (CI= 0.08). Furthermore, the mutant strain had a 50% lethal dose (LD) three-fold that of the parental strain. These results, together with the fact that the ΔTn mutant was isolated as a STM clone reveal that the locus of is required for full growth and pathogenesis on rainbow trout.

Mots clés: host-limited replication

P. Reimundo, A. Menéndez, J. Méndez, D. Pérez-Pascual, R. Navais, et al.. gene mutation in the teichoic acids alanylation system of results in diminished proliferation in its natural host.. Veterinary Microbiology, 2010, 143 (2-4), pp.434. ⟨10.1016/j.vetmic.2009.12.004⟩. ⟨hal-00594816⟩