Protein Extraction from <i>Chlorella pyrenoidosa</i> Using <i>Bacillus</i> spp. Isolated from <i>Jeotgal</i>: Strain isolation, Characterization, and Fermentation

<i>Chlorella pyrenoidosa</i>, a versatile microalga with a rich nutritional profile and functional components, has various applications. However, rigid cell walls pose challenges for the effective extraction of proteins. Microbial fermentation is a promising solution for large-scale production and industrial applications. This study aimed to isolate <i>Bacillus</i> spp. with high enzymatic activity from Jeotgal, a Korean traditional fermented food, and enhance protein extraction from <i>C. pyrenoidosa</i> using microbial fermentation with the isolated <i>Bacillus</i> spp. Twenty-two strains of <i>Bacillus</i> spp. were isolated, and eight <i>Bacillus</i> species were selected based on their ability to produce cellulases, proteases, and lipases. Microbial safety was further assessed by testing for biogenic amine production and hemolytic activity. All eight strains exhibited γ-hemolysis, with four strains not producing biogenic amines. Notably, fermentation using <i>Bacillus amyloliquefaciens</i> F2 showed the highest protein extraction yield at 35.45 ± 1.21% (v/v). In conclusion, this study demonstrates the potential of microbial fermentation for protein extraction from <i>C. pyrenoidosa</i>, offering a novel approach for its utilization in the food industry.