Influence of rhizobacterial culture media on plant growth and oninhibition of fungal pathogens

The type of culture media significantly influenced thegrowth-promoting or growth-inhibiting effect of sevenPseudomonas spp. isolates on cucumber, as didthe type of bacterial isolate. All the bacterialisolates also inhibited fungal growth, in vitroand the degree of inhibition depended on the growthmedium of the two cultures. The degree of inhibitionwas affected by the growth-rate of the fungalpathogen. Proteolytic activity was detected in thesupernatants of the cultures of six out of sevenbacterial isolates and was media-dependent. Highproteolytic activity was measured in supernatants ofbacteria grown in two organic-based media, Tryptic SoyBroth and SNB nutrient broth, and/or in a Mineralmedium. In contrast, proteolytic activity was almost undetectable after growth in King's B medium. Proteolytic activity was significantly increased when the concentration ofproteose peptone in King's B medium was reduced by 50and 75 percent.