Recombinant Fusion Protein Containing Plant Nigellothionin Regulates the Growth of Food-Spoiling Fungus (Aspergillus niger)

This study aimed to obtain a recombinant chimeric protein named trx-NsW2 via theheterologous expression of the multifunctional antimicrobial peptide nigellothionin from black cumin (Nigella sativa L.) seeds in the Escherichia coli system. The protein was purified using a combination of Ni-NTA affinity chromatography and reversed-phase HPLC. Based on the HPLC calibration, the total yield of the protein was calculated to be 650 mg/L of bacterial culture. The fungistatic activity of trx-NsW2 against the food-spoiling fungus Aspergillus niger was demonstrated as itinhibited the maturation of conidiawithout affecting conidial germination or fungal growth. In contrast to mature nigellothionin NsW2, the fusion protein showeda low level of cytotoxicity towards both normal and tumor cell lines at concentrationsof up to 100–200 µM. Interestingly, at lower concentrations, it even stimulated cytokinesis. These findings are of critical importance for applying chimeric antimicrobial proteins obtained via microbiological synthesis in applied science.