Selective Medium for the Detection of Pseudomonas pseudoalcaligenes subsp. konjaci, the Causal Agent of Bacterial Leaf Blight of Konnyaku (Amorphophallus konjac)

Abstract

A selective medium (PPSM) was developed for the detection of Pseudomonas pseudoalcaligenes subsp. konjaci (Ppk), the causal agent of bacterial leaf blight of konnyaku (Amorphophallus konjac), from plant debris and soil. The composition of the medium was as follows: 0.5g KH₂PO₄, 3.0g Na₂HPO₄⋅12H₂O, 6.0g sodium tartrate, 2.0g (NH₄)₂SO₄, 10μg L-leucine, 0.29g MgSO₄⋅7H₂O, 67mg CaCl₂⋅2H₂O, 0.25mg Na₂M₀O₄⋅2H₂O, 20mg phenol red, 2mg methyl violet, 12.5mg ampicillin sodium, 25mg cycloheximide, 50mg thiram-benomyl wettable powder, 15g agar in 1 liter of distilled water. Colony forming efficiency of Ppk on PPSM was higher than that on King B medium. Reduction percentage of soil bacteria on PPSM ranged from 81.6 to 92.5% of the total number of soil bacteria recovered on nutrient broth yeast extract agar. Ppk was easily detected from the residue of diseased leaflet by using PPSM.