ABSTRACT
The overuse of chemical pesticides to cure or prevent plant diseases has caused soil pollution and had harmful effects on human beings. It is desirable to replace chemical pesticides with materials that possess the following three criteria: high specificity against the targeted plant pathogens, easy degradability after effective usage and low cost of mass production. Pseudomonas strains are most active and dominant bacteria in the rhizosphere and have been intensively investigated as biocontrol agents. The strains of Pseudomonas produce several kinds of antibiotics, such as pyrolnitrin, pyoluteorin, and phenezine-1-carboxylate, all of which are closely related to the suppression of plant diseases. The use of the gram-positive Bacillus species as a biocontrol agent and has been studied less intensively than that of the gram-negative bacteria. B. subtilis is a good candidate for solid-state fermentation and the product treated by the bacterium can be utilized as an organic material that functions both as an organic fertilizer and a microbial pesticide.
