Plasmid Profiles of Lactose-Negative and Proteinase-Deficient Mutants of Streptococcus lactis C10, ML(3), and M18.
Lactose- and proteinase-negative (Lac Prt) mutants of Streptococcus lactis C10, ML3, and M18 were isolated after treatment with ethidium bromide. The Lac Prt mutants of C10 were missing a 40-megadalton plasmid. A 33-megadalton plasmid was absent in the ML3 mutants, and the M18 variants lacked a 45-megadalton plasmid. The results suggest a linkage of these metabolic traits to the respective plasmids. The possible complexity of the interrelationship between lactose metabolism and proteinase activity is presented.
Kuhl
S A
SA
Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108.
Larsen
L D
LD
McKay
L L
LL