Selective isolation of Actinoplanes and Dactylosporangium from soil by using γ-collidine as the chemoattractant

Abstract

Zoospores of the actinoplanetes Actinoplanes missouriensis and Dactylosporangium thailandense were attracted to a number of amino acids, aromatic compounds and sugars. Among these compounds, d-xylose and γ-collidine served as universal chemoattractants for most or all of other 9 species belonging to the genera, and moreover, γ-collidine always elicited an extremely strong response. In contrast, potassium chloride was a weak to moderate attractant only for a half of the strains tested. Palleroni's chemotactic method (Palleroni, N.J., Arch. Microbiol., 128, 53–55, 1980) for the isolation of motile actinoplanetes was complemented by using γ-collidine as a substitute for the originally used chemoattractant, potassium chloride, and by using humic acid-vitamin (HV) agar in place of the isolation medium, starch-casein agar. The improved method not only enabled the increased recovery of Actinoplanes spp. but also the consistent recovery of Dactylosporangium spp., which have only incidentally been isolated by the original method and by conventional dilution plating techniques, from various field soils (16 samples). The recovery of motile actinoplanetes was more successfully achieved by using HV agar supplemented with nalidixic acid to reduce associated bacterial contaminants.