The two-component bacteriocin Lac705 induces the amplification and rearrangement of plasmid pRC18 and reverts the Lac-negative phenotype of the Lactobacillus curvatus SAC7 mutant.

TATIANA M. STEPANENKO, MARÍA C. ARISTIMUÑO FICOSECO, RAÚL R. RAYA

Villa Carlos Paz, Córdoba, Argentina

Congreso; VI CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL Sociedad Argentina de Microbiología General SAMIGE; 2009

SAMIGE

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> MM-P24 THE TWO-COMPONENT BACTERIOCIN LAC705 INDUCES THE AMPLIFICATION AND REARRANGEMENT OF PLASMID PRC18 AND REVERTS THE LAC705-NEGATIVE PHENOTYPE OF THE Lactobacillus curvatus SAC7 MUTANT. Tatiana M. Stepanenko1, María C. Aristimuño Ficoseco1, Raúl R. Raya1 1CERELA-CONICET (tatula17@hotmail.com) Lactobacillus curvatus CRL705 produces two bacteriocins (antimicrobial peptide): Lactocin 705 (Lac705) and Antilisteria 705 (AL705), and harbors the plasmids pRC12 (12 Kb) and pRC18 (18,66 Kb), being the last plasmid associated with production of Lac705. Sac7, a mutant derived from CRL705, is negative in the production of both bacteriocins, in spite of containing the plasmid pRC18. When Sac7 cells were incubated in the presence of a free-cell supernatan of the wild-type Lactobacillus curvatus CRL705, the mutant phenotype of Sac7( Lac705−/S-AL705−/R) reverted to the wild-type phenotype (Lac705+/R-AL705+/R), and kept stable after several generations. The induction factor was identified as the bacteriocin Lac705 itself. PCR studies, using specific primers of pRC18, suggested that the bacteriocin-negative phenotype of strain Sac7 could be due both to the low copy-number and to structural rearrangement of plasmid pRC18.