Fungal L-Asparaginase from environmental isolates with antimicrobial and antibiofilm activities

Fourteen fungal species were isolated from sewage water and soil, of which ten strains showed positive extracellular L-asparaginase production by plate assay. Among them, Aspergillus nidulans AUMC17371, A. flavus AUMC17373, A. flavus AUMC17374, and A. terreus AUMC17372 exhibited the highest enzyme activities (1.35, 1.25, 0.97, and 0.79 U/mL, respectively). Optimization of culture conditions revealed that maximum production was achieved using fructose as carbon source, asparagine as nitrogen source, pH 6, and 30 °C. SDS-PAGE analysis confirmed enzyme production, with protein bands ranging from 35 to 45 kDa. Antimicrobial screening revealed strong activity against Gram-positive and Gram-negative bacteria; however, only limited antifungal effectiveness against Candida albicans was exhibited. MIC results showed that L-asparaginase from A. nidulans AUMC17371 showed the strongest antibacterial effect against Staphylococcus aureus , followed by A. flavus AUMC17373 against S. aureus and Pseudomonas aeruginosa . Antibiofilm assays indicated inhibition ranging from 22 to 69%, with A. flavus AUMC17373 showing the most potent effect. Cytotoxicity testing revealed that A. flavus AUMC17374 enzyme exhibited anticancer activity against MCF-7 and HepG2 cell lines with IC 50 values of 184 and 450 µg/mL, respectively. Computational analysis supported these findings, with molecular docking demonstrating stable binding of L-asparagine to A. nidulans AUMC17371 L-asparaginase (− 4.67 kcal/mol), and molecular dynamics indicating a structurally stable enzyme–substrate complex. Collectively, these results suggest that fungal L-asparaginase may serve as a promising candidate with antimicrobial, antibiofilm, and cytotoxic activities.