A Novel Bacillus amyloliquefaciens Specifically Improving the Solubility and Antioxidant Activities of Edible Bird's Nest.

Edible bird's nest (EBN), a most highly priced and valuable foodstuff, contains high percentage of proteins and carbohydrates. However, proteins adhering to these carbohydrates make the EBN hard and tough, which need to be boiled as the bird's nest soup to make the Chinese cuisine. To overcome the hard and tough texture of EBN and improve the digestion degrees, the present study screened and identified a probiotic strain Bacillus amyloliquefaciens YZW02 from 5-year stored EBN sample completely solubilizing EBN for the first time. The 24-h B. amyloliquefaciens fermented EBN contained 20.30-21.48 mg/mL of the soluble protein contents with a recovery rate of 98-100%, DPPH radical scavenging rate of 84.76% and ABTS radical scavenging capacity of 41.05%. The mixed fermentation of B. amyloliquefaciens YZW02 and Bacillus natto BN1 were further applied to improve the low-MW peptide percentages and antioxidant activities. The mixed-fermentation of B. natto BN1 with 4-h cultured B. amyloliquefaciens YZW02 had the lowest percentage (82.23%) of >12-kDa proteins/peptides and highest percentages of 3-12 kDa, 1-3 kDa and 0.1-1 kDa peptides of 8.6% ± 0.08, 7.57% ± 0.09, 1.77% ± 0.05 and 0.73% ± 0.05, with the highest DPPH, ABTS and OH scavenging capacity of 90.23%, 46.45% and 49.12%, respectively. These findings would provide an efficient strategy for improving the solubility and antioxidant activities of EBNs.