Fatty acid ester biosurfactant from Lysinibacillus sphaericus HS8: Statistical modeling, characterization, and...

Finding a safe and efficient broad-spectrum antiviral agent is the main focus of recent research with increasing desires for biosurfactants as therapeutic agents. This study aimed to produce and characterize biosurfactant from Lysinibacillus sphaericus and determine its antiviral activities against both Herpes simplex virus type 1 (HSV-1) and Hepatitis A virus (HAV). The initial oil displacement zone for biosurfactant screening was 8.75 ± 0.35 cm. Statistical modeling using Plackett-Burman design and Quadratic Box-Behnken design showed a final higher displacement zone of 14.5 ± 0 cm with a 98.95 % validation percentage. The yield of the purified biosurfactant was high (9.96 g/L). The characterization by Fourier-transformed infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H NMR), and gas chromatography-mass spectrometry (GC-MS) confirmed the presence of fatty acid ester biosurfactant. The purified biosurfactant was tested on Vero cells and showed a 50 % cytotoxic concentration (CC50) of 293.55 ± 1.73 μg/mL and a maximum non-toxic concentration (MNTC) of 125 μg/mL. The antiviral results showed high effects against HAV (85.87 %) and HSV-1 (70.89 %) with a 50 % inhibitory concentration (IC50) of 56.89 ± 0.87 μg/mL and 83.6 ± 0.82 μg/mL, and a selectivity index (SI) of 5.16 and 3.51, respectively. This study opened the way to the production of novel biosurfactants with strong and broad-spectrum antiviral activity.