Developing a heterotrophic fed‐batch cultivation strategy for high‐yield arginine‐rich protein production using Chlorella vulgaris UTEX 395 and nutritional evaluation

BACKGROUND Chlorella sp. are promising candidates due to their rapid growth, high protein content (>400 g kg −1 ), and lower land/water requirements compared to conventional crops. However, autotrophic cultivation is limited by low biomass, which hinders large‐scale application. Heterotrophic cultivation of Chlorella typically yields low protein content (<400 g kg −1 ) and limited arginine, a conditionally essential amino acid critical for juveniles and aquaculture species. In this study, Chlorella vulgaris UTEX 395 was screened as a potential strain for the production of high‐value arginine‐rich protein. Additionally, the heterotrophic fed‐batch strategy using C. vulgaris UTEX 395 offers a feasible and effective approach for producing high‐yield superior protein. RESULTS C. vulgaris UTEX 395 cultivated in HA‐SK medium achieved the highest biomass (14.12 g L −1 ), protein content (355.7 g kg −1 ), and arginine (38.0 g kg −1 ) among the five Chlorella strains. After fed‐batch cultivation under screened favorable nutrient supply conditions, this microalga attained 19.26 g L −1 biomass with 509.7 g kg −1 protein and 66.0 g kg −1 arginine of dry biomass. Moreover, the established process was further evaluated in the 100 L fermenter. At the end of cultivation, the biomass of C. vulgaris reached 52.3 g L −1 , with a protein content of 555.0 g kg −1 and arginine content of 83.2 g kg −1 . Furthermore, C. vulgaris UTEX 395‐derived protein and arginine were higher than those of other Chlorella species, soybean, egg, and fish meal. CONCLUSION C. vulgaris UTEX 395 cultivated by the established heterotrophic fed‐batch strategy is a potential candidate to produce high‐value protein with a high level of arginine for food and animal feed applications.