Cultural, biochemical and physiological studies of Ralstonia solanacearum causing wilt of brinjal

Abstract

Bacterial wilt caused by Ralstonia solanacearum is a lethal disease of brinjal in tropical, subtropical and warm temperate regions of the world. In present investigation, isolation of the biochemical and physiological characterization of R. solanacearum was conducted. The results of the various cultural and biochemical characters revealed that the bacterium isolates were rod shaped, Gram negative, non-capsulated. They appeared dull white with light pink colored center on TZC medium and the colonies were highly fluidal producing copious slime. The bacterium was positive for nitrate reduction test and negative for starch hydrolysis and gelatin liquification. Physiological studies viz., Effect of temperature and effect of pH on the growth of R. solanacearum on CPG agar medium was studied. The temperature of 30 oC was found optimum for the growth of pathogen as the highest population (196.66 x 105cfu/ml) were recorded at this temperature level followed by 25 oC (114.66 x 105cfu/ml) and 35 oC (103.33 x 105cfu/ml) and the maximum number of bacterial colonies were recorded at pH 7 (154.00 x 105cfu/ml).