Investigating synergistic effects of key medium components and pectin elicitor on taxane fermentation in Neopestalotiopsis vitis: A Box–Behnken response surface methodology approach

Taxanes are high-value diterpenoid compounds with potent anticancer activity, notably used in the treatment of breast and ovarian cancers. The newly isolated Iranian endophytic fungus Neopestalotiopsis vitis (N. vitis), recovered from native hazelnut (Corylus avellana) tissues, has demonstrated the ability to biosynthesize paclitaxel. However, maximizing its biotechnological potential requires a well-optimized culture system that accounts for synergistic interactions between nutritional factors and elicitor treatments. In this study, Response Surface Methodology (RSM) employing a Box–Behnken Design (BBD) was used to systematically investigate the individual and synergistic effects of four parameters—pH (4.0–8.0), malt extract (1.0–5.0 g L⁻¹), (NH₄)₂SO₄ (1.25–5.0 mM), and hazelnut-derived pectin (50–150 mg flask^− 1)—on fungal biomass accumulation and total taxane fermentation. Model analysis confirmed pH 6.0 as the major factor with a significant linear effect on both responses, enhancing biomass and total taxane yield by approximately ⁓1.4-fold and 80%, compared to pH 4.0 and pH 8.0, respectively. Among binary interactions, malt extract and (NH₄)₂SO₄ exerted the strongest synergistic impact on the biomass rate (F = 44.39), resulting in an increase of ⁓27.0 g compared to other combinations. In contrast, the synergistic interplay between (NH₄)₂SO₄ and pectin most profoundly enhanced the total taxane yield (F = 67.98), with an improvement exceeding 1200 µg gFW⁻¹ (fresh weight). Collectively, these findings not only establish an optimized framework for scalable taxane fermentation from N. vitis, but also reveal how precisely coordinated synergies among carbon, nitrogen, and a host-derived elicitor orchestrate fungal secondary metabolism.