FIG. 1.

Checkerboard DNA-DNA hybridization format. Shown is the membrane used to detect 13 bacterial species (Capnocytophaga gingivalis, Capnocytophaga sputigena, Fusobacterium nucleatum, Pseudomonas aeruginosa, Porphyromonas gingivalis, Prevotella intermedia, Peptostreptococcus micros, P. nigrescens, A. actinomycetemcomitans a and b, Tannerella forsythensis, V. parvula, and Streptococcus mutans) in 24 subgingival biofilm samples from healthy subjects. Vertical lanes 1 to 24 contained DNA extracted from the samples. The rightmost lanes are standards containing DNA amounts equivalent to 10⁴, 10⁵, 10⁶, and 10⁷ cells of each species tested for. The horizontal rows contained the indicated DNA probes diluted in hybridization buffer. An asterisk at the intersection of the horizontal rows and vertical lanes indicates the presence of a species. The intensity of the signals obtained is proportional to the amount of DNA immobilized in the membrane.