Antibacterial activity of endophytes isolated from Calendula officinalis L. against some animal pathogens.

Objectives: Medicinal Plants have the ability to synthesize a wide variety of chemical compounds that are used to perform important biological functions. Endophytes are microbial (bacteria or fungi) colony which resident inside of healthy plant tissues and have useful antibacterial, antiviral and anticancer activity.In this study, we focused on the isolation of bacterial endophytes from one medicinal plant: Calendula officinalis L. and screening them for activities against some field isolates of animal bacterial pathogens.Materials and Methods: Random samples from asymptomatic leaves and branches of Calendula officinalis L. was collected for isolation of endophytic bacteria, the disinfected portions of the plant were distributed onto the isolation media. To examine endophytic bacterial contents, the bioassays were conducted using growing colonies in PA(pepton agar) and YEA(yeast extract agar) inactivating them by chloroform. Isolates of Escherichia coli were isolated from dead poultry referred to veterinary clinic of Shahr-e-kord university by regional poultry farms. Staphylococcus aureus were isolated from mastitis cow’s milk in our previous works. Results and conclusion: A total of 5 phenotypically distinguishable bacterial endophytes were isolated in pure form from Calendula officinalis L. (3 leaf, 2 branches). 3 endophytes isolated from this plant had more effective antibacterial activity against indicator bacterial pathogens.Generally, Endophytic microorganisms reside in Calendula officinalis L. are a very promising source for production of bioactive compounds at least against some field isolates of pathogenic bacteria.