Related Experiment Videos
Divergence of Genomic Sequences between Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris
J J Godon1, C Delorme, S D Ehrlich
1Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France.
Applied and Environmental Microbiology
|December 1, 1992
Summary
DNA hybridization reveals Lactococcus lactis subspecies lactis and cremoris are distinct groups, with 20-30% DNA divergence. This supports a new classification based on DNA homology and differing phage sensitivities.
Area of Science:
- Microbiology
- Bacteriology
- Genetics
Background:
- Lactococcus lactis subspecies lactis and cremoris are important dairy starter cultures.
- Phenotypic characteristics have been traditionally used to differentiate these subspecies.
- Previous classifications may not fully capture the genetic relatedness between these groups.
Purpose of the Study:
- To assess the genetic relatedness between Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis.
- To propose a revised classification based on DNA homology.
- To investigate if DNA homology correlates with phage sensitivity.
Main Methods:
- Southern hybridization analysis using cloned chromosomal genes as probes.
- DNA sequence divergence estimation.
- Phage sensitivity testing.
Main Results:
- Strains of L. lactis subsp. lactis and L. lactis subsp. cremoris form two distinct genetic groups.
- Estimated DNA sequence divergence between the subspecies is 20-30%.
- Phage sensitivity profiles are distinct between the two subspecies, aligning with the proposed DNA homology-based classification.
Conclusions:
- Phenotypic criteria are insufficient for fully discriminating between L. lactis subsp. lactis and L. lactis subsp. cremoris.
- A new classification based on DNA homology is proposed.
- Distinct phage sensitivities support the revised classification of these subspecies.