Identification and Cultivation of Pseudomonas fluorescens Antagonistic to Pseudomonas tolaasii

Pseudomonas tolaasii 길항세균인 Pseudomanas fluorescens의 분리 및 배양

Pseudomanas fluorescens was selected from mushroom and studied in both batch and continuous culture in order to find out optimum conditions for cultivation. P. fluorescens is an aerobic bacterium and antagonistic to Pseudomonas tolaasii which causes blotch disease on the mushroom cap. Cells of P. fluorescens were grown well on medium containing 30g/L of glucose, whereas the growth was inhibited with the glucose concentration at higher than 30g/L. The highest value of specific growth rate and productivity were obtained when using 10g/L of yeast extract. Optimum concentrations of $NH_4Cl$ and $(NH_4)_2SO_4$ for culture were found to be 1.0g/L and 0.1g/L respectively. Optimum concentration of $MgSO_4{\cdot}7H_2O$ used as a sulfur source was 1.0g/L. It was also found that the cell concentrations were at the maximum level when grown on the medium containing 1.0g/L of $KH_2PO_4$ and 0.1g/L of $CaCl_2$. Also, the optimum culture conditions were $30^{\circ}C$ and pH 6.0. Cultivation of P.fluorescens at high initial dissolved oxygen (D.O) value led to a decrease of bacterial productivity in batch culture. Maximum productivity was achieved at 68 for the initial D.O value.

버섯 갈변병 유발세균인 P. tolaasii에 길항성을 나타내는 P. fluorescens를 분리하였으며, 대량배양을 위하여 최적 배지조성 및 배양의 최적조건을 확립하였다. 세포성장에 있어서 carbon및 energy source인 glucose의 경우 30g/L일 때 세포농도가 가장 높았으며, yeast extract의 농도가 10g/L까지 증가함에 따라 세포농도도 증가하였다. 질소원인 $NH_4Cl$과 $(NH_4)_2SO_4$는 각각 1.0g/L와 0.1g/L일 때 세포성장이 가장 좋게 나타났고, sulfur source인 $MgSO_4{\cdot}7H_2O$의 최적농도는 1.0g/L였다. 그리고 $KH_2PO_4$와 $CaCl_2$는 각각 1.0g/L와 0.1g/L일 때 세포농도가 가장 좋았고 온도 $30^{\circ}C$, pH6.0그리고 초기 D.O를 68로 유지시켰을 때 세포성장이 가장 높았으며, 균체 비증식속도($\mu$)와 생산성도 높았다.