Red tilapia by-product hydrolysates: A new nitrogen source for Bifidobacterium lactis HN019

Background

Red tilapia by-products possess ample protein and are either discarded or processed into low-value products. The nitrogen source is the most expensive part of the microbial culture, so finding a cheap alternative can better promote the microbial economy. In this study, different combinations of enzymes were used to hydrolyze the by-products of red tilapia, and its effects on the growth of Bifidobacterium lactis HN019 were investigated.

Results

The results showed that hydrolysate hydrolyzed by enzyme combination 4 (alcalase: neutrase: papain: flavorzyme = 1:1:2:1) (EC4) obtained the highest nitrogen recovery (53.63%) and >2000 Da peptide proportion (5.07%). Hydrolysate hydrolyzed by enzyme combination 2 (alcalase: neutrase: papain: flavorzyme = 2:1:1:1) (EC2) has less hydrophobic amino acids and could improve the growth rate in 10 h–14 h in 50% nitrogen source substitution but had worst viable count after 24 h cultivation.

Conclusion

These results indicated that red tilapia by-product hydrolysate was an excellent nitrogen source substitution and suggested that the hydrophobic amino acids in the nitrogen source might be an essential factor affecting the growth of Bifidobacterium lactis HN019. This research enhanced the economic value of red tilapia by-products, minimized the waste of aquatic resources, and provided directions for the utilization of red tilapia by-products.