Bioactivity and enzymatic properties of culturable endophytic fungi associated with black seeds (Nigella sativa L.)

Extracellular enzymes of the endophytes are degraders of the polysaccharides available in the host plants. The study evaluated the activity of amylase, protease, lipase, and laccase enzymes produced by one hundred endophytes previously isolated from the seed. In addition, their antimicrobial activity against Listeria monocytogenes, Staphylococcus aureus (ATTC 25923), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853) was determined using the disc diffusion assay. The data show that 93% of the isolates were capable of producing amylase, followed by protease, lipase, and laccase with 72%, 81%, and 10%, respectively. Out of 100 endophytic fungi, only nineteen (n = 19) displayed activity against the target bacteria. Of the 19 endophytic fungi showing antibacterial activity, 9 (47%) belonged to the Penicillium genus, 5 (26%) to Alternaria spp, 3 (16%) to Cladosporium, and only 1 (5%) to the Fusarium genus. The highest antibacterial activities against all pathogenic bacteria tested were recorded for Alternaria alternata (MH879772.1) and Penicillium goetzii (MF151170.1). In conclusion, the study not only demonstrates the array of extracellular enzymes produced by the endophytes isolated from black seeds but also reports on their antibacterial properties, thus highlighting the importance of these endophytes in the development of endophyte-based technologies and drug development against resistance pathogenic bacteria.