Physical map of the chromosome of Lactococcus lactis subsp. lactis DL11 and localization of six putative rRNA operons

• Published in: Journal of Bacteriology Vol. 173; no. 9; pp. 2768 - 2775
• Main Authors: Tulloch, D.L. (University of Melbourne, Parkville, Victoria), Finch, L.R, Hillier, A.J, Davidson, B.E
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.05.1991
• Subjects: Blotting, Southern; CARTE GENETIQUE; CHROMOSOME; CROMOSOMAS; Electrophoresis, Gel, Two-Dimensional; Genes, Bacterial; Lactococcus lactis - genetics; Lactococcus lactis lactis; MAPAS GENETICOS; Operon - genetics; Plasmids; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Restriction Mapping; RNA - genetics; RNA Probes; STREPTOCOCCUS LACTIS; Transcription, Genetic
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.173.9.2768-2775.1991

A physical map of the chromosome of Lactococcus lactis subsp. lactis DL11 was constructed by using the contour-clamped homogeneous electric field mode of pulsed-field gel electrophoresis in one- and two-dimensional separations to analyze restriction digests of high-molecular-weight genomic DNA. The map, which shows all the observed NotI and SmaI sites (six and 21, respectively) and 8 of approximately 30 SalI sites, is circular and yields a total size of 2.58 megabase pairs for the L. lactis subsp. lactis DL11 chromosome. By using rDNA from Mycoplasma capricolum to probe Southern blots of pulsed- and fixed-field digestion patterns, six putative rRNA operons were identified in L. lactis subsp. lactis DL11 and placed on the map of the chromosome. Five of these loci are clustered in a region representing only 20% of the chromosome. The presence of a SmaI site in each of the putative operons allowed the direction of transcription of each operon to be deduced