Study on a 50 L Pilot-Scale Fermentation Process for Lycopene Production by Komagataella phaffii

Lycopene is a carotenoid with potent antioxidant activity. Microbial fermentation has emerged as a promising production platform owing to its natural origin, safety, and independence from seasonal constraints. However, most high-yield studies rely on extensive metabolic engineering and are conducted at the 3–7 L laboratory scale, with limited research on pilot-scale process development. In this study, a recombinant Komagataella phaffii (formerly Pichia pastoris) strain Pp-F2-G1-035 producing lycopene was used to systematically investigate shake-flask medium optimization, high-density fermentation, and 50 L pilot-scale process development, using a pre-engineered strain, with no further metabolic engineering performed in this study. The optimal shake-flask medium was identified as 0.8× BSM basal salts medium supplemented with 5 g/L peptone, achieving a lycopene titer of 261.4 mg/L—approximately 172% higher than with standard BSM. After iterative optimization in 5 L and 10 L bioreactors, the 50 L pilot trial employed a three-stage high-density seed train. A representative batch reached 3.37 g/L after 139 h of fermentation, while an extended fermentation batch (198 h) yielded 3.70 g/L. The specific lycopene yield per unit biomass in the 50 L bioreactor was comparable to that in the 10 L system, providing a preliminary 50 L-scale demonstration. Notably, a basal level of lycopene accumulation (0.045–0.19 g/L) was detected during the glycerol feeding phase prior to methanol induction, suggestive of possible partial derepression of P_AOX1. The production strain exhibited stable lycopene production across 9 serial passages (mean 228.3 mg/L, CV 9.7%), indicating good phenotypic production stability across passages. This work provides a preliminary 50 L-scale process demonstration, establishing a technical basis for further scale-up evaluation of lycopene production by K. phaffii.