基于动力学模型的法夫酵母发酵生产虾青素的补料策略优化

Kinetic Model for Optimal Feeding Strategy in Astaxanthin Production by Xanthophyllomyces dendrorhous

摘要:

对法夫酵母的不同补料发酵方式进行了研究。基于底物抑制模型, 提出了一种优化的两阶段补料策略, 用于法夫酵母产虾青素的高密度发酵。在发酵的延迟期和对数生长期早期, 糖浓度控制在25 g/L左右, 在此条件下, 生物量可以达到最大, 且时间缩短。在对数生长期后期及稳定期, 糖浓度控制在5 g/L, 虾青素的合成时间可以有效延长。与传统的补料方式相比, 采用此补料策略取得了较好的发酵效果。发酵终点细胞干重达到23.8 g/L, 虾青素产量达到29.05 mg/L, 分别比分批发酵提高了52.8%和109%。

Abstract:

Astaxanthin is a useful pigmentation source in fish aquaculture. It has strong antioxidative activity and therefore has potential application in delaying aging and degenerative diseases in human and animals. In recent years, there is a growing demand for astaxanthin. The red yeast Xanthophyllomyces dendrorhous (called Phaffia rhodozyma before) is one of the most promising microorganisms for the commercial production of astaxanthin. During fermentation, X. dendrorhous shows the Crabtree effect. Higher glucose concentration will cause significant reductions in biomass and astaxanthin production. Therefore, fed-batch processes are particularly useful. In this paper, effects of glucose-feeding strategies on astaxanthin production by X. dendrorhous were studied. Based on the substrate inhibition model, an optimized two-stage feeding strategy for astaxanthin production of high-cell-density fermentation was proposed. Glucose concentration was first controlled at about 25 g/L during the lag phase and the early exponential phase. In such case, biomass could reach its maximum value in relatively short time. Then the glucose concentration was controlled at about 5 g/L in the later exponential phase and stationary phase. The synthesis of astaxanthin could be effectively prolonged. The results showed that the optimized two-stage feeding strategy was the best among all the feeding strategies, and could obtain the highest biomass (23.8 g/L) and astaxanthin production (29.05 mg/L), which was a significant increase (52.8% and 109% respectively) compared with a batch process.