Abstract: Two strains of chitinolytic bacteria respectively named "Corynebacterium Bine-A" "Achromobacter Bine-B", which were deposited under deposit numbers FERM BP-2879 and FERM BP-2880 in the Fermentation Research Institute, Agency of Industrial Science and Technology, Japan. At least one of these strains is incubated on a chitin or chitosan medium, to prepare a culture material, which is usable directly as a solid antibacterial composition or fermented or aged to produce a solid antibacterial composition. Alternatively, water is added to the prepared culture material, and either of the liquid and solid phases may be used as an antibacterial, anti-nematode, and/or plant-cell activating composition.