Isolation and characterization of a novel hydrolase-producing probiotic Bacillus licheniformis and its application in the fermentation of soybean meal

Abstract

Soybean meal (SBM) is one of the most important sources of plant-based protein in the livestock and poultry industry. However, SBM contains anti-nutritional factors (ANFs) such as glycinin, β-conglycinin, trypsin inhibitor and phytic acid that can damage the intestinal health of animals, inevitably reducing growth performance. Fermentation using microorganisms with probiotic potential is a viable strategy to reduce ANFs and enhance the nutritional value of SBM. In this study, a novel potential probiotic Bacillus licheniformis (B4) with phytase, protease, cellulase and xylanase activity was isolated from camel feces. The ability of B4 to tolerate different pH, bile salts concentrations and temperatures were tested using metabolic activity assay. It was found that B4 can survive at pH 3.0, or 1.0% bile salts for 5 h, and displayed high proliferative activity when cultured at 50°C. Furthermore, B4 was capable of degrading glycinin, β-conglycinin and trypsin inhibitor which in turn resulted in significant increases of the degree of protein hydrolysis from 15.9% to 25.5% (p < 0.01) and crude protein from 44.8% to 54.3% (p < 0.001). After fermentation with B4 for 24 h, phytic acid in SBM was reduced by 73.3% (p < 0.001), the neutral detergent fiber (NDF) and the acid detergent fiber of the fermented SBM were significantly decreased by 38.40% (p < 0.001) and 30.20% (p < 0.05), compared to the unfermented SBM sample. Our results suggested that the effect of solid-state fermented SBM using this novel B. licheniformis (B4) strain, could significantly reduce phytic acid concentrations whilst improving the nutritional value of SBM, presenting itself as a promising alternative to phytase additives.

Effect of microbial fermentation on the quality of soybean meal

“…There is an increasing evidence that lactic acid bacteria have the ability to degrade proteins during fermentation and lactic acid bacteria with high intestinal adhesion also have antibacterial properties (Ma et al ., 2022). Antioxidant, anti‐inflammatory and antihypertensive activities were also found in fermented soybean meal (Cui et al ., 2020; Yao et al ., 2021; Qi et al ., 2023). Further research has shown that the fermented soybean meal can improve intestinal barrier function and reduce inflammation of piglets, which is more suitable for poultry feed and aquaculture (Cheng et al ., 2019a).…”

Isolation and identification of protease-producing Bacillus amyloliquefaciens LX-6 and its application in the solid fermentation of soybean meal

“…SM not only contains high protein content and excellent amino acid (AA) quality but also large amounts of antioxidant compounds such as flavonoids and phenols ( Lee et al, 2022 ). SM is often used as a cheap and high-quality protein raw material for poultry feeding and in livestock industries ( Qi et al, 2023 ). The recent development of the aquaculture industry has resulted in a lack of protein sources for aquaculture feed and more expensive conventional raw materials, such as fish meal ( Caimi et al, 2021 ).…”