The motility and chemotactic behavior of the soil actinomycete
Catenuloplanes japonicus IFO 14176 was studied. The mature growth on the humic acid-vitamin agar medium exhibited the abundant formation of dichotomously branched aerial hyphae, from which motile, flagellated spores, or zoospores, were released upon immersion into a 10
−2 M phosphate buffer (pH 7.0) containing 10% soil extract. A quantitative microcapillary assay revealed that the zoospores are significantly attracted to a variety of organic compounds common to the soil environments. Monosaccharides such as
L-arabinose,
D-xylose,
D-glucose and
D-galactose served as positive chemoattractants at considerably low concentrations; the maximum responses to the compounds occurred at 10
−5 to 10
−3 M, and the thresholds were 10
−6 to 10
−5 M. Amino acids (
D-alanine,
L-glutamate, and
L-proline), aromatic compounds (vanillin, vanillate, protocatechuate, and myricetin), uronic acid (α-
D-galacturonate) and amino sugars (
D-glucosamine, and
N-acetyl-
D-glucosamine) all elicited concentration-dependent positive responses within the range of 10
−4 to 10
−1 M. Of the tested compounds, vanillin at 10
−1 M provided the strongest response. The chemotactic activities of
C. japonicus should tend to bring it toward the appropriate ecological locations where concentrated food sources are present. The Palleroni chemotactic method based on the 10
−1 M-vanillin attraction achieved the selective isolation of
Catenuloplanes spp. from natural soil samples
View full abstract