Fermentation of NaHCO3-treated corn germ meal by Bacillus velezensis CL-4 promotes lignocellulose degradation and nutrient utilization

• Published in: Applied microbiology and biotechnology 2022-09, Vol.106 (18), p.6077-6094
• Main Authors: Chen, Long, Chen, Wanying, Zheng, Boyu, Yu, Wei, Zheng, Lin, Qu, Zihui, Yan, Xiaogang, Wei, Bingdong, Zhao, Zijian
• Format: Article
• Language: English
• Subjects: Adenine; Adenosine; Amino acids; Bacillus velezensis; Baking; Biomedical and Life Sciences; Biotechnological Products and Process Engineering; Biotechnology; Cecum; Cellulose; Corn; Degradation; Electron microscopy; Fatty acids; Feed industry; Feed quality; Fermentation; Fermented food; Food industry; Gene sequencing; Genomes; Hemicellulose; Life Sciences; Lignocellulose; Metabolites; Microbial Genetics and Genomics; Microbiology; Nutrient utilization; Nutritive value; Pretreatment; Probiotics; Proteins; Sodium; Sodium bicarbonate; Solid state fermentation; Substrates; Surface structure; Trichloroacetic acid; Vegetables
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-022-12130-7

Sodium bicarbonate pretreatment and solid-state fermentation (SSF) were used to maximize the nutritional value of corn germ meal (CGM) by inoculating it with Bacillus velezensis CL-4 (isolated from chicken cecal contents and capable of degrading lignocellulose). Based on genome sequencing, B. velezensis CL-4 has a 4,063,558 bp ring chromosome and 46.27% GC content. Furthermore, genes associated with degradation of lignocellulose degradation were detected. Pretreatment of CGM (PCGM) with sodium bicarbonate (optimized to 0.06 g/mL) neutralized low pH. Fermented and pretreated CGM (FPCGM) contained more crude protein (CP), soluble protein of trichloroacetic acid (TCA-SP), and total amino acids (aa) than CGM and PCGM. Degradation rates of cellulose and hemicellulose were reduced by 21.33 and 71.35%, respectively, after 48 h fermentation. Based on electron microscopy, FPCGM destroys the surface structure and adds small debris of the CGM substrate, due to lignocellulose breakdown. Furthermore, 2-oxoadipic acid and dimethyl sulfone were the most important metabolites during pretreatment. Concentrations of adenosine, cytidine, guanosine, S -methyl-5’-thioadenosine, and adenine decreased significantly after 48 h fermentation, whereas concentrations of probiotics, enzymes, and fatty acids (including palmitic, 16-hydroxypalmitic, and linoleic acids) were significantly improved after fermentation. In conclusion, the novel pretreatment of CGM provided a proof of concept for using B. velezensis CL-4 to degrade lignocellulose components, improve nutritional characteristics of CGM, and expand CGM lignocellulosic biological feed production. Key points • Sodium bicarbonate (baking soda) can be used as an economical and green additive to pretreat corn germ meal; • Fermentation with B. velezensis degrades the cellulose and hemicellulose component of corn germ meal and improves its feed quality; • As a novel qualified presumption of safety (QPS) strain, B. velezensis should have broad potential applications in food and feed industries.