A novel two-stage heterotrophic cultivation for starch-to-protein switch to efficiently enhance protein content of Chlorella sp. MBFJNU-17. (January 2022)

• Record Type: Journal Article
• Authors: Xiao, Xuehua; Zhou, Youcai; Liang, Zhibo; Lin, Rongzhao; Zheng, Mingmin; Chen, Bilian; He, Yongjin
• Is Part Of: Bioresource technology. Volume 344:Part A(2022)
• Publication Date: 2022-01
• Subjects: Microalga -- Heterotrophic Chlorella -- Two-stage cultivation -- Starch, protein; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2021.126187
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: A two-stage cultivation was developed to produce Chlorella biomass rich in protein. The process was implemented using a heterotrophic Chlorella sp. MBFJNU-17 strain. Microalga accumulated starch in the first-stage cultivation after urea consumption. The starch-to-protein switch of microalga was driven by the second-stage cultivation. Microalga treated by the two-stage cultivation attained around 60% protein content. Abstract: This work aimed to firstly establish an efficient and novel two-stage cultivation process to produce microalgal biomass rich in protein using a heterotrophic Chlorella sp. MBFJNU-17 strain. In the first-stage cultivation, to reduce the glucose and urea utilization, microalga achieved a high biomass at 40 g/L glucose and 1 g/L urea; meantime, the expression from starch biosynthesis genes of microalga was up-regulated under nitrogen-starvation conditions for starch accumulation (55.01%). In the second-stage cultivation, based on the over-compensation effect, Chlorella cells after the first-stage cultivation were further treated at 5 g/L glucose and 3 g/L urea to up-regulate starch degradation, central carbon metabolism and urea absorption genes expression to drive intracellular starch-to-protein switch for biosynthetic protein (59.75%). Moreover, microalga performed similar characteristics in a 10-L fermenter by the established process. Taken together, Chlorella sp. MBFJNU-17 was the promising candidate to produce high-value biomass enriched in protein by the established two-stage cultivation.