Antagonistic effect of Erwinia herbicola on in vitro spore germination and germ tube elongation of Botrytis cinerea and Penicillium expansum

Interaction between Erwinia herbicola and Botrytis cinerea and Penicillium expansum was studied in liquid culture. The results show that the bacteria directly inhibited spore germination of both fungi, especially during the first hours of the paired cultivation. The distinct taxis of bacteria to spores and germ tubes was frequently followed by their lysis. It is likely that bacteria act also by competition for nutrients. The rate of antagonistic activity of the bacteria against both fungi depended on their concentration in the mixture. Formation of chlamydospore-like structures at the apical end of B. cinerea germ tube suggests induction of a defence mechanism of this fungus while in unfavourable conditions.