Endophytic Streptomyces rochei BpR-2 GER (ON142045) from Bryophyllum pinnatum (Lam.) Oken with Antimicrobial and Antibiofilm Potential

Objectives: To explore the endophytic actinobacteria from the root tissue of Bryophyllum pinnatum (Lam.) Oken and its assessment for antimicrobial and antibiofilm activity against human pathogens. Methods: Surface sterilized root tissues of B. pinnatum have been seeded in different isolation media, to obtain colonies of endophytic actinobacteria. A polyphasic approach has been used to identify the isolate. Cross streak and disc diffusion methods have been used to perform the antimicrobial activity. However, the crystal violet assay assessed the antibiofilm activity, and its visualization was done under the light and fluorescent microscope. Findings: By polyphasic approach, Actinobacteria strain BpR-2 GER has been confirmed to be the member of genus Streptomyces, further through 16S rRNA gene sequence analysis, the strain has been identified as Streptomyces rochei that has 100% sequence similarity with Streptomyces rochei NRRL B-2410 (MUMD01000370). The isolate has exhibited extensive antagonistic interaction with Clinical and MTCC (Microbial Type Culture Collection) pathogens ranging from 9.750.71 to 19.381.30 mm. The highest zone of inhibition was recorded against Gram-positive bacteria B. subtilis (MTCC-441) of 19.381.30 mm and Gram-negative bacteria Proteus mirabilis (Clinical) of 16.250.71 mm. The strain has also exhibited significant antibiofilm potential against the MTCC-7443 (85.130.003 to 88.280.003%) and Clinical (85.130.003 to 88.280.003%) strain of Staphylococcus aureus. Novelty: This is the first report of S. rochei BpR-2 GER, a root endophyte of B. pinnatum with broad-spectrum antimicrobial activity and a significant antibiofilm property. Keywords: Antimicrobial activity; Antibiofilm activity; Bryophyllum pinnatum; Endophytic Actinobacteria; Streptomyces rochei