Vibrio harveyi, V. anguil- larum, V. vulnificus and V. damsela were precultured in LB brothincubatedat28 Cfor2 dand50 llofthisculturewere spread over the agar plates. Bacillus spp. culture (3 d old) was centrifugedat9600 rev min)1 for15 minandthesupernatant fluid filtered through a 0Æ22-lm membrane filter (Sartorius, Bedford, MA, USA) to obtain cell-free extracts (culture supernatant fluid). A volume (100 ll) of Bacillus cell-free extracts was introduced into the wells of the agar medium and incubated for a period of 24–48 h at 28 C.