Nanocoating of quinoa protein and hyaluronic acid enhances viability and stability of Limosilactobacillus fermentum RC4 microcapsules

Nanocoating represents an effective strategy for creating a protective barrier on probiotic surfaces, preventing them from damage. Here, we developed HAQ microcapsules comprising Limosilactobacillus fermentum RC4, which were nanocoated with hyaluronic acid and quinoa protein. We characterized the stability and safety, and investigated the intermolecular forces and transcriptome to elucidate the mechanisms underlying the nanocoating. The encapsulation efficiency, survival rates following freeze drying, simulated oro-gastrointestinal conditions, and storage at 4 °C for 56 d were 10.32 %, 12.74 %, 7.56 %, and 14.56 % higher, respectively, than those of LF RC4 alone. The HAQ microcapsules demonstrated adhesion to Caco-2 cells and safely promoted proliferation in RAW 264.7 cells. Electrostatic and hydrophobic interactions emerged as the primary forces within the HAQ microcapsules, facilitating structural rearrangements of wall materials, promoting the ordered aggregation of quinoa protein, and enhancing the stability of microcapsules. Transcriptome analysis revealed that HAQ upregulated argF and carB involved in lysine and glutamic acid biosynthesis, while downregulating mraY and murG associated with carbohydrate biosynthesis. It is postulated that these regulatory effects may enhance bacterial metabolism and proliferation, thereby facilitating the exertion of functional properties such as adhesion. Our findings offer valuable insights into the development of highly active and stable probiotic freeze-dried powders.