Differentiation between strains ofFlavobacterium breve and allied bacteria by comparisons of deoxyribonucleic acids

Chromosomal deoxyribonucleic acid was isolated and purified from 10 strains ofFlavobacterium breve, originating from human or other animal sources. The mean and standard deviation for the species in base content was 32.4±0.6% G+C, and in genome size was 3.21±0.37×10⁹ daltons. In vitro DNA reassociation showed that sevenF. breve strains (mainly from human sources) had high levels of intraspecific base sequence similarity (>70%) as derived from reassociations done at the optimum temperature of reassociation (TOR) or TOR—10°C (nonstringent conditions). The three otherF. breve strains contained a high degree of base sequence divergence. All 10 strains ofF. breve were readily distinguishable in their DNA characteristics fromF. meningosepticum, F. odoratum, and allied Gram-negative bacteria.