Guanine Plus Cytosine Content of the Deoxyribonucleic Acid of the Leuconostocs and Some Heterofermentative Lactobacilli

The mole percent guanine plus cytosine in the deoxyribonucleic acid of 12 strains (6 species) of Leuconostoc and 9 strains (4 species) of slime-forming heterofermentative lactobacilli has been determined. Calculated from melting-temperature curves, the values were in the range 40 to 47%, but calculated from buoyant-density determinations they were 2 to 4% lower. The melting temperature of the reference deoxyribonucleic acid from Escherichia coli K-12 was 0.7 to 1 degree higher than the expected figure of 90.6 C. This point is discussed.