Characterization and production optimization of genistein by the novel endophytic fungus Aspergillus sydowii J11 isolated from pigeon pea (Cajanus cajan) and its antibacterial and antioxidant properties
摘要
Genistein, a bioactive isoflavone predominantly found in legumes, has garnered considerable attention for its diverse health-promoting benefits. Given the limitations of conventional plant extraction and chemical synthesis, microbial production offers a sustainable and efficient alternative. Endophytic fungi represent a promising reservoir of bioactive metabolites. However, reports on genistein-producing fungal endophytes remain scarce. In this study, the genistein-producing capabilities of endophytes isolated from pigeon pea (Cajanus cajan) were investigated. Five endophytes including three strains of Fusarium solani (G6, G34, G38), F. oxysporum (G44), and Aspergillus sydowii (J11), were identified as novel genistein producers, with A. sydowii J11 being the most effective. Genistein was identified through UV spectroscopy, HPLC, UPLC-MS/MS, and NMR analysis. Under optimized fermentation conditions (potato dextrose broth supplemented with 2% fructose and 1% beef extract, pH 6.0, 28 °C, 10 days), A. sydowii J11 produced genistein at 128.85 mg/L—a 5.4-fold increase over the baseline and the highest microbial genistein yield reported to date. The fungal-derived genistein demonstrated potent antibacterial activity against Staphylococcus aureus and Bacillus subtilis (MIC = 6.25 mg/L), and moderate activity against Escherichia coli and Serratia marcescens (MIC = 12.5 mg/L). Additionally, it exhibited significant antioxidant capacity, with an EC₅₀ of 156.81 mg/L in the DPPH assay. These findings position A. sydowii J11 as a promising candidate for large-scale genistein production and a natural source of antibacterial and antioxidant agents for food and pharmaceutical applications. This work represents the first report of genistein biosynthesis by endophytic fungi from pigeon pea, highlighting the potential of A. sydowii J11 as a sustainable microbial platform for high-yield genistein production.