Developing an efficient open-pond microalgae cultivation system for producing biomass and fucoxanthin using Pavlova granifera IML2238

Fucoxanthin is a marine carotenoid recognized for its strong antioxidant and free radical scavenging properties. However, most research on microalgae-based fucoxanthin production has been limited to laboratory scales (typically under 200 liters), providing limited insights for commercial applications. Therefore, there is an urgent need to establish scaled-up fucoxanthin-producing systems. In this study, a 6-ton open-pond system was employed to produce fucoxanthin using a fucoxanthin-rich microalgal strain Pavlova granifera IML2238. With an inoculum size of 0.10 g/L, batch cultivation achieved biomass and fucoxanthin productivity of 74.9 and 3.24 mg/L/d, respectively. A semi-batch process, replacing 50 % of the medium volume in each cycle, resulted in biomass and fucoxanthin productivity of 80.2 and 4.31 mg/L/d, respectively. Repeated semi-batch replacement at 50 % maintained stable biomass and fucoxanthin productivity at 73.7 and 4.05 mg/L/d. The fucoxanthin produced demonstrated high antioxidant activity , with a total phenolic content of 29.8 mg GAE/g, confirming its potential for commercial use. • A large-scale microalgal fucoxanthin production system was successfully demonstrated. • A 0.1 g/L inoculum minimized contamination risks under non-sterile conditions. • Semi-batch cultivation (50 % replacement ratio) produced fucoxanthin at 4.31 mg/L/day. • Long-term semi-batch operations enable stable fucoxanthin production in open ponds.