Study of antibacterial activity of Streptomyces sp. SS473 isolated from plants against ESBL-producing Escherichia coli

Abstract

The broad spectrum β-lactamase-producing E. coli (ESBL) is a dangerous bacterial pathogen in humans due to its resistance to many antibiotics. This is especially serious in the context of a limited number of new antibiotics for treating bacterial infections. This leads to a global public health threat and places an urgent need for new antibiotics. In this study, the authors investigated the antibacterial properties of an actinomyces strain isolated from the plant Clinacanthus nutans against the ESBLproducing E. coli strains. These actinomyces strains were designated as SS473. Moreover, SS473 showed a broad spectrum of antibacterial activity on several clinically isolated pathogenic bacteria. Culture media have different effects on the antibacterial activity of SS473. In stability tests, the antibacterial activity of strain SS473 remained at a temperature up to 80oC but was lost at pH 3 and 13. By contrast, the antibacterial activity was not affected by UV and protease treatments. Based on the results of morphological identification with specific
media for Streptomyces and molecular identification on 16S rRNA gene, strain SS473 was suggested to belong to the Streptomyces genus and was named Streptomyces sp. SS473. The results in this study will pave the way for the following research on the identification of secondary metabolites having antibacterial activity and their biosynthetic pathways in Streptomyces sp. SS473 in the future.