Generation and characterization of a depigmented variant of Chlorella pyrenoidosa for application in food products

• Published in: Food bioscience 2024-10, Vol.61, p.104823, Article 104823
• Main Authors: Ge, Mengdie, Liu, Bin, Mao, Xuemei, Huang, Junchao, Cheng, Ka-Wing
• Format: Article
• Language: English
• Subjects: Chlorella pyrenoidosa; Depigmentation; Emulsion; Mutant; Pigment biosynthesis
• ISSN: 2212-4292; 2212-4306
• DOI: 10.1016/j.fbio.2024.104823

Microalgae are promising natural resources for an array of essential nutrients and health-promoting compounds. The past decade has witnessed their increasing popularity as a value-added ingredient in the food industry. However, some of their intrinsic properties, especially their typical green color and off-flavor, may compromise consumer acceptability and remain a key challenge for food scientists. This study aimed to generate and characterize a chemically induced pigment-deficient mutant (C49) of Chlorella pyrenoidosa. In contrast to the wild type (WT), C49 could not grow photoautotrophically or mixotrophically. However, when grown heterotrophically, it exhibited a growth curve similar to that of WT. Pigment analysis verified the presence of only trace amounts of chlorophylls (0.27 ± 0.02 mg/g) and carotenoids (0.036 ± 0.003 mg/g) in the C49 which were only ∼1.7% and ∼1% of those in the WT, respectively. C49 also had higher carbohydrate (62.75% ± 2.42%) and lower protein (26.54% ± 1.00%) content than the WT (37.41% ± 2.25% and 36.21% ± 1.97%, respectively). Genetic assays revealed inactivation of the phytoene desaturase gene as a key mechanism underlying the reduced xanthophyll-synthesizing capability of C49, thus causing its failure to accumulate chlorophyll and develop chloroplasts. Transcriptomic and RT-PCR analyses indicated that the high carbohydrate content was likely due to reduced starch degradation. Furthermore, C49 demonstrated an emulsifying capacity comparable to that of WT over a wide pH range (3–8) in oil-in-water emulsions consisting of 5% cell-disrupted homogenate in deionized water and rapeseed oil (1:1, v/v). The results of this study support that depigmented Chlorella pyrenoidosa possesses promising potential for application in the food industry. [Display omitted] •A depigmented C. pyrenoidosa mutant was generated by ethyl methane sulfonate induced mutagenesis.•Disruption of phytoene desaturase contributed to depigmentation of C. pyrenoidosa.•Reduced starch degradation led to higher carbohydrate content in the mutant.•Cell-disrupted homogenate of the mutant formed stable oil-in-water emulsions.