Partial purification and characterization of Lactococcus lactis TW34 bacteriocin

CYNTHIA SEQUEIROS; MARISA GARCÉS; MARISOL VALLEJO; ROGELIO MARGUET; PEDRO BARÓN; CLAUDIA NATALUCCI; NELDA LILA OLIVERA

Puerto Madryn, Chubut, Argentina.

Congreso; SAIB. XLVI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Bacteriocins are antimicrobial peptides and proteins produced by some bacteria to kill or inhibit the growth of other bacteria. Recently, bacteriocins have been considered for potential use in human health, veterinary medicine, and food preservation. The aim of this study was to purify and to characterize L. lactis TW34 bacteriocin, which shows a broad inhibition spectrum of Gram-positive fish pathogens. The cell-free supernatant was ethanol fractionated and subjected to ion-exchange chromatography (SP-Sepharose) by FPLC at pH 4.5. The collected fractions were evaluated for antimicrobial activity (agar well diffusion assay) against Lactococcus garvieae. Active fractions were pooled and analyzed by Tricine-SDS-PAGE, also detecting bacteriocin activity in the gel. Already described bacteriocin genes (nisin, lacticin 481, and lactococcin A) were assessed by PCR amplification using specific primers. TW34 bacteriocin was partially purified by cationic exchange chromatography. Its apparent molecular weight was about 4.2 kDa; a value close to that of nisin (3.5 kDa). Only nisin gene (898 bp partial sequence) was detected in L. lactis TW34. In addition, TW34 was resistant to nisin produced by the reference strain L. lactis subsp. lactis ATCC 11454. These results suggested that L. lactis TW34 produces a nisin-like bacteriocin.