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Characterization of Lactococcus garvieae isolated from radish and broccoli sprouts that exhibited a KG + phenotype, lack of virulence and absence of a capsule
Author(s) -
Kawanishi M.,
Yoshida T.,
Kijima M.,
Yagyu K.,
Nakai T.,
Okada S.,
Endo A.,
Murakami M.,
Suzuki S.,
Morita H.
Publication year - 2007
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2007.02114.x
Subject(s) - virulence , biology , subculture (biology) , microbiology and biotechnology , mutant , lactococcus , 16s ribosomal rna , bacteria , strain (injury) , pathogen , gene , genetics , lactococcus lactis , lactic acid , anatomy
Aims: To identify Lactococcus garvieae isolates from radish and broccoli sprouts and compare them with virulent and less virulent mutant strains obtained from yellowtails with regard to KG phenotype, presence of a capsule and virulence towards yellowtails and mice. Methods and Results: Comparative 16S rRNA gene sequence analysis of six isolates obtained from radish and broccoli sprouts indicated that they were L. garvieae (similarity >99%). They were compared with KG9502, Lg2 and ATCC49156 strains obtained from yellowtails. A less virulent mutant strain Lg2‐S was obtained by Lg2 subculture. Biochemical characterization of the six strains resembled that of KG9502, Lg2, ATCC49156 and Lg2‐S, except for saccharose and tagatose acidification and the presence of hippuricase. These six strains were nonpathogenic towards yellowtails and mice, nonsusceptible to bacteriophages and demonstrated heterogeneity on pulsed‐field gel electrophoresis analysis. Using transmission electron microscopy, a capsule was observed in KG9502 and Lg2 but not in ATCC49156 and Lg2‐S. Conclusions: We isolated L. garvieae strains that lacked pathogenicity towards yellowtails and mice from radish and broccoli sprouts; these were noncapsulated and exhibited KG + phenotype. Significance and Impact of the Study: This is the first documentation of L. garvieae isolated from terrestrial plants. These isolates exhibited genetic diversity; however, they were noncapsulated and nonpathogenic towards yellowtails and mice.