First report on isolation of Mucor bainieri from honeybees, Apis mellifera: Characterization and biological activities.

Fungi are potential biocontrol agents and rich sources of secondary metabolites with demonstrated biological activities. This study aimed to isolate and identify fungi from surface-sterilized honeybees (Apis mellifera), as well as to evaluate their biological activities. One fungal isolate was obtained and identified morphologically and genetically as Mucor bainieri MK-Bee-2. Gas chromatography-mass spectroscopy (GC-MS) analysis of fungus crude extract, showed the existence of six major metabolites representing 92.48% of the total peak area. The crude extract of Mucor bainieri MK-Bee-2 was tested for antimicrobial, antioxidant, and antitumor activities. It demonstrated wide antimicrobial activities against human pathogenic Gram-positive and Gram-negative bacterial strains, as well as Candida albicans, with MIC values ranged from 62.5 to 250 µg/ml. The results revealed that the extract exhibited considerable antioxidant activities indicated by strong inhibition of both DPPH and ABTS free radicals. Additionally, the extract exhibited greater potential anticancer activity against both adenocarcinomic human non-small cell lung cancer cells (A549) [IC50 = 6.45 µg/ml], and immortal cell line hepatoma G2 (HepG2) human liver cancer cells [IC50 = 27.48 µg/ml] and higher selectivity in cancer cells than normal cell lines. Furthermore, the extract showed less cytotoxic activity against normal cells with higher IC50 values of 106.99 and 132.57 µg/ml against human lung fibroblast Wistar-38 (Wi-38) and oral epithelial cells (OEC), respectively. Taken together, the Mucor bainieri MK-Bee-2 extract comprises bioactive compounds as promising potential therapeutic candidates for the treatment of lung cancer. Strikingly, the extract sensitizes the lung cancer cells A549  to the ionizing radiation through the pro-apoptotic pathway as indicated by the annexin V flow cytometry analysis which showed that the extract reduced the apoptosis of lung cancer cells.