Novel production of vinblastine by immobilized cultures of mutant strain of the endophytic Alternaria alternata.

Vinblastine is a clinically important anticancer alkaloid, and the development of efficient microbial production systems remains a promising strategy for improving its sustainable availability. In the present study, Alternaria alternata Mut-85 was evaluated for vinblastine production using immobilized fungal cultures. Five entrapment carriers, were compared using both spore and mycelium immobilization. Calcium alginate was the most effective for vinblastine production by immobilized spores and mycelia, reaching 2.15 ± 0.08 and 2.75 ± 0.03 mg L⁻¹, respectively. Mycelium-loaded alginate beads were therefore selected for further process development. Optimization of cultivation conditions showed that vinblastine production was favored by 12 days of incubation at 25 °C, 100 mL medium volume, and 100 beads per flask. Response surface methodology was then applied to optimize the immobilization parameters, recording the optima of 105.21 g L⁻¹ for sodium alginate, 145.10 g L⁻¹ for fresh biomass, and 60 g L⁻¹ for calcium chloride, giving a predicted vinblastine concentration of 5.95 mg L⁻¹, closely matching the experimental value of 5.88 mg L⁻¹. Nutrient fed strategies further improved production, with the separated four-pulse feeding program giving the highest titer of 7.04 ± 0.25 mg L⁻¹ and productivity of 0.587 mg L⁻¹ day⁻¹. Repeated-batch cultivation confirmed the reusability of immobilized beads, with the first two cycles maintaining high vinblastine titers of 7.00 ± 0.24 and 6.81 ± 0.36 mg L⁻¹. Overall, this study establishes alginate-immobilized A. alternata Mut-85 as an efficient and reusable platform for enhanced fungal vinblastine production.