The diversity of a collection of 102 lactococci including 91 Lactococcus lactis isolates of dairy and non-dairy origin was explored using partial Small SubUnit (SSU) rRNA gene
 sequence analysis and limited phenotypic analyses. A subset of 89 strains of L. lactis
 subsp. cremoris and L. lactis subsp. lactis isolates was further analyzed by (GTG)5-PCR
fingerprinting, and a novel Multi-Locus Sequence Analysis (MLSA) scheme. Two major
 genomic lineages within L. lactis were found. The L. lactis subsp. cremoris type-strain
like genotype lineage included both subspecies cremoris and lactis isolates. The other
major lineage, with a L. lactis subsp. lactis type-strain-like genotype, comprised L. lactis
subsp. lactis isolates only. A novel third genomic lineage represented two L. lactis subsp.
 lactis isolates of non-dairy origin. The genomic lineages deviate from the subspecific
classification of L. lactis that is based on a few phenotypic traits only.
MLSA of six partial genes (atpA encoding ATP synthase alpha subunit; pheS encoding
phenylalanine tRNA synthetase; rpoA encoding RNA polymerase alpha chain; bcaT
encoding branched chain amino acid aminotransferase, pepN encoding aminopeptidase N
 and pepX encoding X-prolyl dipeptidyl peptidase) revealed 363 polymorphic sites (total
length: 1970 bases) among 89 L. lactis subsp. cremoris and lactis isolates with unique
sequence types for most isolates. This allowed high resolution cluster analysis in which
dairy isolates form subclusters of limited diversity within the genomic lineages. The pheS
DNA sequence analysis yielded two genetic groups dissimilar to the other genotyping
analysis based lineages, indicating a disparate acquisition route for this gene.

العنوان

Applied and Environmental Microbiology

الناشر

American Society for Microbiology

بلد الناشر

الولايات المتحدة الأمريكية

Indexing

Thomson Reuters

معامل التأثير

3,823

نوع المنشور

مطبوع فقط

المجلد

83

السنة

2007

الصفحات

33