Environmental factors affecting the antagonism of Pseudomonas cepacia against Trichoderma viride.

Antagonistic activity of the bacterium Pseudomonas cepacia against Trichoderma viride was greatly influenced by nutritional and environmental conditions. Xylose and trehalose strongly enhanced the antifungal activity of P. cepacia, whereas mannitol and glucose had little effect. The carbon sources that enhanced the antagonistic activity also inhibited sporulation of T. viride. Antagonism of P. cepacia was enhanced by ammonium nitrogen; however, with nitrite or nitrate there was only a little antagonism. The antagonism of P. cepacia was optimal at pH 5.0. Although P. cepacia showed maximum antagonism against T. viride at 37 degrees C, the antagonism was fairly good at temperatures as low as 18 degrees C, indicating that there is a broad range of temperature for the antifungal activity of P. cepacia.