Cultivation conditions for mass production of detoxifying bacterium Pseudomonas sp. HC1 of tolaasin produced by Pseudomonas tolaasii

Abstract

S : Several bacteria are known as the causal agents of diseases of the cultivated button mushroom(Agaricus bisporus) and oyster mushroom(Pleurotus ostreatus). Pseudomonas tolaasii is the causal agent of brown blotch disease of commercial mushrooms. Pseudomonas sp. HC1 is a potent biological control agent to control brown blotch disease caused by Pseudomonas tolaasii. This can markedly reduce the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. To define the optimum conditions for the mass production of the Pseudomonas sp. HC1, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 5.0 and 20 o C, respectively. The optimal culture medium for the growth of tolaasin inhibitor bacterium was determined as follows: 0.9% dextrin, 1.5% yest extract, 0.5% (NH 4 ) 2 HPO 4 , 4mM FeCl 3 , and 3.0% cysteine.