Effect of Endophytic Serratia marcescens Isolated from Bryophyllum pinnatum against Clinical Bacterial Isolates

Abstract

The world's health is being threatened by antimicrobial resistance (AMR). According to the World Health Organization, it is one of humanity's top ten worldwide public health problems. Serratia marcescens is an opportunistic pathogen that can be isolated from soil, plants, water, and air. Additionally, Serratia species offer a valuable supply of secondary metabolites that are comparatively underutilised and may have anti-MDR pathogenic properties. The present research aimed to determine the antibacterial potential of Serratia marcescens isolated from the leaves of Bryophyllum pinnatum against clinical bacterial isolates. The leaves of Bryophyllum pinnatum were collected, surface sterilised, cultured at 37 °C for 24 hours and identified utilising viteks 2 automated techniques and molecular methods. The crude metabolites extract of Serratia marcescens were extracted and utilised for antibacterial susceptibility testing using agar healthy diffusion methods. The data were measured in the diameter zone of inhibition. This study revealed six endophytic bacteria were isolated from Bryophyllum pinnatum following standard microbiological culture methods. The endophytic bacteria isolate tag L03 was found to be Gram-Negative Rod. The isolate was tentatively identified as Serratia ficaria and molecularly identified as Serratia marcescens. The metabolites of Serratia marcescens endophytes revealed a significant antibacterial activity on Klebsiella pneumoniae with a diameter zone of inhibition of 17.7 mm at 100% concentration, followed by Staphylococcus sciuri with a 12.7 mm diameter zone of inhibition. These results suggested that endophytic bacteria Serratia marcescens were isolated from the leaves of Bryophyllum pinnatum and had shown potent antibacterial activity that could be employed to create new antibacterial agents.