Abstract: Our objective was to optimize nutritional and environmental conditions of the isolated Serratia marcescens Ba-2 and Pseudomonas fluorescens Ba-11 for biomass production and to evaluate the bio-control agents against the root knot disease caused by Meloidogyne incognita on Faba bean plants under greenhouse conditions. Glycerol at 10.2 g/L and peptone as a nitrogen source were the most suitable for biomass and antagonistic efficiency of S. marcescens or P. fluorescens against Meloidogyne sp. Cultures of S. marcescens and P. fluorescens supplemented with 10 g/L peptone, reduced larvae to 91% and 95% respectively. Optimum biomass and antagonistic activity of either bacteria against larvae was at pH 7.6, and incubation temperature at 30 o C. 100% reduction of larval density was achieved when S. marcescens or P. fluorescens cultures were shaken at 120 and 160 rpm respectively. S. marcescens and P. fluorescens were very effective as biocontrol agaents to reduce the rootknot nematodes. Our data also indicate a marked effect of the biocontrol agents and Rhizobia on the growth response of faba plants. The obtained results showed that both bacterial treatments significantly increased the growth parameters as well as shoot and root dry weights and number of pods
