A diverse group of plant-growth promoting bacteria were isolated in button mushroom (Agaricus bisporus) media to investigate the plant-growth promoting traits of compounds including indole acetic acid (IAA), ammonia, 1-aminocyclopropane-1- carboxylic acid deaminase, siderophore, and hydrogen cyanide. Twenty-one bacterial strains showing positive effects for all the test traits were selected and classified to confirm bacterial diversity in the media habitat. Plant-growth promoting traits of the isolates were also assessed. All strains produced IAA ranging from 20 μg/mL to 250 μg/mL. Most of the isolates produced more than 80% siderophore. Four strains (Pantoea sp., PSB-08, Bacillus sp., PSB-13, Pseudomonas sp., PSB-17, and Enterobacter sp., PSB-21) showed outstanding performances for all the tested traits. In a bioassay of these four strains using mung bean plant, the best growth performances (23.16 cm, 22.98 cm, 2.27 g/plant, and 1.83 g/plant for shoot length, root length, shoot dry weight, and root dry weight, respectively) were obtained from the plants co-inoculated with Bacillus sp., PSB-13. The resultant data indicate that button mushroom media have got a diverse group of bacteria with plant growth promoting abilities. Thus, the media could be a good recycling resource for using to an effective bio-fertilizer.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
    Isolation of plant-growth promoting bacteria
    Production of indole acetic acid
    Production of ammonia
    ACC deaminase activity
    Production of Hydrogen Cyanide
    Production of siderophore
    Plant growth promotion bioassay with mung bean
    Statistical analysis
RESULTS AND DISCUSSION
    Isolation of plant-growth promoting bacteria
    Production of Indole Acetic Acid
    Production of ammonia
    Production of Hydrogen Cyanide
    ACC deaminase activity
    Production of siderophore
    Plant growth promotion bioassay with mung bean
REFERENCES

• Young-Ho Yeom(Department of Bio-Environmental Chemistry, College of Agriculture and Life sciences, Chungnam National University)
• Jong-Hoon Oh(Department of Bio-Environmental Chemistry, College of Agriculture and Life sciences, Chungnam National University)
• Min-Ho Yoon(Department of Bio-Environmental Chemistry, College of Agriculture and Life sciences, Chungnam National University) Corresponding author