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The Burkholderiasp. isolate 87–11 obtained from basidiospores of Lentinus lepideuswas antagonistic against several Pythiumand Rhizoctoniaisolates. The bacterium was tested against soilborne diseases of five plants caused by P. aphanidermatumand R. solaniby soil and seed application, and its potential as a biocontrol agent is discussed.

Carbaryl is one of the carbamate insecticides widely used in agricultural fields and forests. To restore the environment contaminated with carbaryl application, it is suggested that microbial degradation of carbaryl could be an effective method. Two novel bacterial strains degrading rapidly carbaryl were isolated from forest soil. These strains designated as 19B and 19C were identified as novel species of Arthrobacter, respectively based on main bacterial properties including GC-content, major fatty acid composition, major menaquinone isoprenologue and 16S rRNA gene sequence analysis. Strain 19B started to degrade carbaryl within several hours and completely degraded 50 μg/ml carbaryl in a mineral salt medium within a day. Similarly, strain 19C showed a high degradation ability. Gas chromatography-mass spectrometry analysis showed that the major degradation metabolite is 1-naphthol (M=144) and minor metabolites are 1,4-naphthalenedione (M=158) and 1,4-naphthalenediol (M=160), suggesting a pathway of carbaryl degradation by both strains.

A Gram-positive bacterium was isolated from a rottingPleurotus ostreatusfruiting body that markedly reduced the level of extracellular toxins (i.e., tolaasins) produced byPseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. The isolated bacterium is saprophytic but not parasitic nor pathogenic toP. ostreatus. A low ratio, ca. 10−3cells of the isolated bacterium for oneP. tolaasiicells, was sufficient for detoxification in vitro. Inoculation of the isolated bacterium prevents the development of bacterial disease inP. ostreatusandAgaricus bisporus. The suppression of the disease development, however requires the initial cell density equivalent to ca. 10−1cells of the isolated bacterium for one cells of the pathogen. The effects is ascribed to the inactivation of tolaasin by the live, suppressive bacterial cells, and not to metabolites secreted from the organism into culture media. Examination by conventional bacteriological tests and with testing kits, i.e., MicroStationTMSystem Release 3.5 (Biolog Inc., Hayward, CA), ATB Expression (bioMerieux Inc. Japan) and VITEK (bioMerieux Inc. Japan), failed to assign the organism to any defined bacterial genus. The suppressive bacterium may be useful in future for the development of biocontrol system and/or the construction of genetically modified edible fungi resistant to the disease caused byP. tolaasii.

A Gram-positive bacterium was isolated from a rotting Pleurotus ostreatusfruiting body that markedly reduces the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms, The isolated bacterium is saprophytic but not parasitic nor pathogenic to P. ostreatus.A low ratio, ca. 10-3cells of the isolated bacterium for one P. tolaasiicell, was sufficient for detoxification in vitro. Inoculation of the isolated bacterium prevents the development of bacterial disease in P. ostreatusand Agaricus bisporus.The suppression of the disease development, however, requires the initial cell density equivalent to ca. 10-1cells of the isolated bacterium for one cell of the pathogen. The effect is ascribed to the inactivation of tolaasin by the live suppressive bacterial cells, and not to metabolites secreted from the organism into culture media. Examination by conventional bacteriological tests and with testing kits, i.e., MicroStationTMSystem Release 3.5 (Biolog Inc., Hayward, CA), ATB Expression (bioMerieux Inc. Japan) and VITEK (bioMerieux inc. Japan), failed to assign the organism to any defined bacterial genus. The suppressive bacterium may be useful in future for the development of biocontrol system and/or the construction of genetically modified edible fungi resistant to the disease caused by P. tolaasii.