Isolation of the endophytic and rhizospheric microbiome associated to Polygala spp.: Evaluation of the biotechnological potential and antimicrobial activity

Abstract

Polygala spp. are plants commonly used for the treatment of injuries and sprains. Their roots contain methyl salicylate, a compound known for its analgesic properties. However, important compounds such as alkaloids, flavonoids, terpenes, lignins and coumarins were obtained from this genus. In this context, the Polygala spp. tissues could represent a promising source of natural products, since that several pharmacological effects have been reported for their crude extracts. Therefore, the microbiome associated to these plants and the antimicrobial potential of the natural product extracts produced by these microorganisms was investigated. In this study it has been demonstrated the isolation of a potent substance with a broad-spectrum activity produced by an actinobacteria Rizo Pp Ac-11 isolated from rhizospheric space of white-flower Polygala sp.. The natural product extract was carried out to a C18 fractionation in a H2O/acetonitrile gradient and all fractions (Rizo Pp Ac-11A, Rizo Pp Ac-11B, Rizo Pp Ac-11C, Rizo Pp Ac-11D, Rizo Pp Ac-11E, Rizo Pp Ac-11F, Rizo Pp Ac-11G, Rizo Pp Ac-11H and Rizo Pp Ac-11I) were tested for antimicrobial activity. Excepting Rizo Pp Ac-11A and Rizo Pp Ac-11B, all fractions showed inhibition. However, the fraction Rizo Pp Ac-11C showed a broad-spectrum activity against all tested microorganisms, especially multi resistant pathogens. Considering that, this study demonstrated for the first time the isolation of microorganisms associated with Polygala spp. and the isolation of substances with broad-spectrum activity.