Engineering culture medium for high-yield taxane biosynthesis in Alternaria alternata using RSM: Insights into individual and synergistic effects and cytotoxic validation

Abstract

Engineered mycelial lines hold promise for enhanced production of valuable metabolites, serving as efficient biofactories for target compounds. However, in Alternaria alternata, the optimization of taxane biosynthesis remains constrained by an incomplete understanding of culture medium requirements, environmental factors, and the synergistic interactions among medium components that collectively influence metabolic pathways. In this investigation, the effects of critical culture factors—pH (4.0–8.0), sucrose (10.0–50.0 g L^− 1), (NH₄)₂HPO₄ (1.25-5.0 mmol L^− 1), and pectin (0.7–2.1 mg mL^− 1) as a biotic elicitor—on the biomass rate and total taxane yield were assessed using Response Surface Methodology (RSM). Among the evaluated factors, 50.0 g L^− 1 sucrose independently increased biomass and taxane yield by up to 1.86-fold and 71.74 µg gFW^− 1, respectively. Taxane biosynthesis was maximized (1.9-fold) under acidic conditions (pH 4.0), while biomass accumulation peaked at pH ~ 6.0. Notably, the highest biomass production was observed for the pH–sucrose interaction, reaching approximately 9.1 g flask^− 1whereas the sucrose–(NH₄)₂HPO₄ interaction exhibited the strongest statistical synergy for the taxane content, yielding up to approximately 210 µg gFW^− 1. Desirability function identified the optimal condition at pH 6.2, sucrose 50.0 g L^− 1, (NH₄)₂HPO₄ 3.75 mmol L^− 1,pectin ~ 1.5 mg mL^− 1 and overall desirability = 1.0. Importantly, extracts obtained under high-desirability conditions exhibited a significantly enriched taxane profile and pronounced cytotoxic activity against MCF-7 cells. Collectively, these findings offer a robust and potentially scalable fermentation strategy for enhancing taxane biosynthesis in A. alternata, and underscore the potential of engineered mycelial lines as high-yielding biofactories under optimized conditions.

Keywords

Taxanes / Optimization / Response surface methodology / Synergistic effects / Endophytic fungi

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