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

STEPANENKO TATIANA; MARÍA C. ARISTIMUÑO FICOSECO; RAÚL R. RAYA

Villa Carlos Paz

Congreso; VI Congreso – Sociedad Argentina de Microbiología General; 2009

Sociedad de Microbiología General

Lactobacillus curvatus CRL705 produces two bacteriocins (antimicrobial peptide): Lactocin 705 (Lac705) and Antilisteria 705 (AL705), and habors 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, it was observed that 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, suggest that the bacteriocin-negative phenotype of strain Sac7 could be due both to the low copy-number and to structural rearrangement of plasmid pRC18.