جداسازی و شناسایی باکتری‌ اندوفیت Serattia marcescens و بررسی فعالیت بیوکنترلی آن‌ علیه بیماری بوته‌میری فلفل

Damping off disease is one of the destructive diseases of vegetable and cucurbits plants and two species of soil fungi named Pythium aphanidermatum and Rhizoctonia solani have been reported as the main cause of this disease in different regions of the world including in Iran. In this research, 28 isolates of endophytic bacteria were isolated from the roots and crowns of pepper and other greenhouse plants from different regions of Isfahan province, and were measured and screened in terms of their ability to control seedling death and the growth of pepper seedlings. In the investigation of the antifungal effects of these bacteria against P. aphanidermatum and R. solani fungi by cross-culture method in the laboratory, it was found that one of the endophytic bacteria isolated from pepper with the code EFC2 has a very good controlling power (with diameter Inhibition halo 10 mm) against R. solani fungus, but its effect on the control of P. aphanidermatum fungus was not observed in the laboratory. The results of investigating the effect of inoculation of endophytic bacteria isolated with Nirvin pepper seeds showed that the EFC2 isolate has better performance than the control in terms of plant growth factors such as (germination percentage, seedling fresh weight, seedling dry weight, radicle length and shoot length) and This bacterium reduces the severity of disease caused by P. aphanidermatum and R. solani on pepper seedlings by 32 and 55%, respectively, which reduction of Pythium disease severity is probably due to induced resistance. Also, the evaluation of some useful ingredients in EFC2 bacteria showed that this isolate has the ability to dissolve phosphate and the ability to produce indole acetic acid (IAA), but it is not able to produce siderophore and hydrogen cyanide (HCN). Finally, this isolate was identified as Serattia marcescens bacterium by molecular test using 16SrRNA primers and sequence alignment with other sequences in EzBioCloud database with a similarity percentage of 99.86%. According to the obtained results, it can be said that this isolate can potentially be used in future research against Seedling Death disease or other pepper pathogens in field conditions.