Effect of Contaminant Lead on Arthrobotrys oligospora Growth, Development, Trap Production, Efficiency and Protease Secretion

. Lead concentration has recently increased in country side fields and industrial regions. In the research، the effect of different concentrations of lead acetate on Arthrobotrys oligospora growth، sporulation، trap formation and efficiency and also the activity of the extracellular protease of the fungus investigated. A. oligospora is one of the most important biocontrol agents of plant parasitic nematodes. Results showed that lead acetate in concentration of 150-500 mg l-1 inhibition the fungal growth more than 80 percent and concentration of 500 mg l-1 had the maximum level of inhibition. Fungal sporulation in concentration of 150 mg l-1 and more was significantly reduced in compared to control. Trap formation and efficiency in concentration of 200 mg l-1 and more was reduced، but they increased in 100 mg l-1. Probably low concentration of lead induces trap formation of the fungus. Activity of extracellular protease was also significantly reduced in all concentration tested (100-300 mg l-1)، in comparison to control. According to the results، the application of the fungus in biocontrol management of plant parasitic nematodes should be performed under consideration of different environmental factors as well as pollution and concentration of lead in the soil.