Methods for identification of flavobacteria

Published reports disagree on the best features for detecting and distinguishing between Flavobacterium meningosepticum (biovar IIa) and Flavobacterium species CDC group IIb (biovar IIb; Flavobacterium indologenes). This report discloses that at least some of these disagreements may reflect the methods used. To detect production of indole, a modified Kovács reagent (not Ehrlich) and a buffered tryptophan medium were optimal, but not all strains of these two biovars produced indole. To distinguish the two biovars, hydrolysis of corn starch was preferable to that of soluble potato starch. Both biovars may hydrolyze DNA; the differentiation achieved varied with the methods used. Both biovars presented pigmented growth; only IIb, however, was obviously pigmented on a 2-day blood agar plate. Acidification of D-arabinose definitively distinguished these two biovars; several additional features were useful but not definitive.