Antibacterial Potential of Endophytic Fungi Isolated from Psidium guajava (Guava) Leaf against Escherichia coli and Klebsiella pneumoniae

Abstract

Study’s Novelty/Excerpt • This study investigates the antibacterial potential of endophytic fungi associated with Psidium guajava leaves against Escherichia coli and Klebsiella pneumoniae, revealing novel antimicrobial properties. • Through isolation and identification of eight endophytic fungi, four were found to exhibit significant antibacterial activity. • This work highlights the potential of endophytic fungi from P. guajava as a promising source of new antibacterial agents, contributing to the ongoing search for solutions to antimicrobial resistance. Full Abstract Antimicrobial resistance has been recognized as a major issue of public health concern and it remains a global threat of the health care system. Endophytic fungi associated with medicinal plants are reported as promising reservoir of novel antibiotics. The study aim was to determine the antibacterial potential of endophytic fungi associated with Psidium gaujava leaf against Escherichia coli and Klebsiella pneumoniae. Leaves of P. guajava were surface sterilized and inoculated on plates of Potato Dextrose Agar and incubated at room temperature. Endophytic fungal isolates that emerged were identified using their macroscopic (cultural) and microscopic characteristics. The endophytes were screen for antibacterial activity on E. coli and K. pneumoniae isolates. Antibacterial activity of endophytic fungi ethyl acetate extracts with antibacterial activity was also evaluated against isolates of E. coli and K. pneumoniae by agar well diffusion technique. Minimum Inhibitory Concentrations and Minimum Bactericidal Concentrations of the ethyl acetate extracts were also determined. Eight endophytic fungi were isolated from P. guajava leaves and four had antibacterial activity namely: Gonatobotrys sp. P21, Xylaria sp. P11, Fusarium sp. P22 and Trichoderma sp. P25. The extracts exhibited antibacterial activity with zones of inhibition ranging from 11.5 ± 0.5mm to 18.5 ± 1.5mm for E. coli and 12.5 ± 0.5mm to 21.0 ±1.0mm for K. pneumoniae. The MIC was found to be 500mg/mL and 250mg/mL for E. coli and K. pneumoniae respectively. Endophytic fungi isolated from P. gaujava leaf are potential source of novel antibacterial drug since they possess antibacterial activity against isolates of E. coli and K. pneumoniae.

Keywords

• endophytes
• fungi
• antibacterial
• escherichia coli
• klebsiella pneumoniae