Bacillus amyloliquefaciens MU2 fermentation enhances protein extraction and sensory quality of Chlorella pyrenoidosa

The global demand for sustainable, nutritious protein sources necessitates innovative production strategies. Chlorella pyrenoidosa exhibits potential as a protein source; however, conventional extraction methods are limited in terms of protein extraction efficiency and product sensory attributes and quality. Microbial fermentation may address these challenges by improving protein extraction efficiency, antioxidant-related properties, sensory properties, and facilitating the production of improved microalgal protein materials. We developed a method for producing protein-rich materials through fermentation of C. pyrenoidosa with Bacillus amyloliquefaciens MU2 and optimized the fermentation conditions. Under the optimized conditions (26.6 h, 33.8 °C, and 2.7% inoculum), the predicted protein extraction efficiency was 42.8%, and the actual value was 42.90%. Fermentation enhanced the nutritional and functional qualities of Chlorella proteins and effectively mitigated undesirable flavors. In particular, crude protein content increased from 58.47 ± 0.27% to 78.10 ± 0.20%, while DPPH and ABTS radical scavenging activities increased from 5.01 ± 0.13% to 39.38 ± 0.37% and from 3.10 ± 0.10% to 47.89 ± 0.06%, respectively. Semi-pilot experiments demonstrated similar improvement trends, supporting the feasibility of the proposed process. These results suggest that fermentation with B. amyloliquefaciens MU2 is a promising strategy for improving the extraction efficiency and quality of C. pyrenoidosa -derived protein materials.