In Vitro Apoptosis Induction in a Human Prostate Cancer Cell Line by Thermotolerant Glycolipid from Bacillus licheniformis SV1

A highly potent glycolipid was isolated from a crude oil-contaminated soil bacterium Bacillus licheniformis SV1 (NCBI GenBank Acc. No. KX130852) when grown on a modified mineral salt medium supplemented with 2% oleic acid. The maximum reduction in surface tension of cell-free broth from 71 ± 0.812 to 25.919 ± 0.984 mN/m with 89 ± 0.346% emulsification activity was recorded after 120 h of growth. Glycolipid was purified using chromatographic techniques and the presence of aliphatic chain (C–H stretch) and OH-band was revealed by NMR, GC–MS and FTIR analysis. Stability of glycolipid up to 250 °C and its complete decomposition at 507 °C was recorded by thermogravimetric analysis (TGA). MTT assay (IC 50 = 0.473 ± 0.048 mg/ml) along with 4′,6-diamidino-2-phenylindole (DAPI) and acridine orange and ethidium bromide (AO/EtBr) staining validated that glycolipid induces cell apoptosis in human prostate cancer cell line (PC-3). Furthermore, potent anti-cancerous compounds such as 9-octadecanoic acid (22.55%), linoleic acid methyl ester (2.2%) and palmitic acid (1.18%) were also detected in the GC–MS spectra of the purified glycolipid.