Pleurotus ostreatus L-asparaginase's use in food safety and biotechnology: from processing assistance to bioactive...

L-ASNase has attracted attention in many biomedical and food safety applications. Therefore, this study was designed to identify a novel and promising candidate for the sustainable biosynthesis of extracellular L-ASNase from P. ostreatus AUMC 16015 grown on various agricultural substrates under solid-state fermentation (SSF). Also, the enzyme's wide-ranging bioactivities were examined, involving its antioxidant, anti-inflammatory, and antitumor properties, while evaluating its potential applications in food processing.

Optimal P. ostreatus AUMC 16015 L-ASNase production was 56.47 U/mL, which was attained under SSF conditions where the enzyme yield increased by 2.46-fold compared to pre-optimization conditions. Enzyme high purity was validated by a single distinct band at approximately 48 kDa on both SDS-PAGE and native PAGE analyses. The enzyme demonstrated high substrate specificity (K_m = 7.7 mM; V_max = 167.78 U/mL). Functionally, it exhibited strong antioxidant activity (2,2-diphenyl-1-picrylhydrazyl) (DPPH) IC₅₀ = 48.28 µg/mL) and a robust anti-hemolytic effect (95.9% at 1000 µg/mL). L-ASNase exhibited its most potent inhibitory effect against Caco-2 cells at an IC₅₀ of 5.49 ± 0.03 µg/mL, followed by MCF-7, which showed a slightly higher IC₅₀ of 5.86 ± 0.08 µg/mL. Furthermore, L-ASNase significantly mitigated potato chips acrylamide formation, achieving a 9.6-fold decrease after 120 min of treatment. Additionally, Gas chromatography-mass spectrometry (GC-MS) showed that the potato's chemical profile was significantly changed by L-ASNase treatment, with the introduction of numerous bioactive substances and the elimination of some potentially dangerous components.

The biochemical activity of the purified L-ASNase suggested potential biomedical and food applications. This study is a trial for cost-effective enzyme production and supports a circular bioeconomy by converting waste into useful bioproducts. Future work should focus on scaling up production and testing its effects in living organisms to unlock this enzyme's full commercial and medical potential.