Journal
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
Volume 106, Issue 18, Pages 6077-6094Publisher
SPRINGER
DOI: 10.1007/s00253-022-12130-7
Keywords
Bacillus velezensis CL-4; Corn germ meal; Lignocellulose-degrading enzyme; Sodium bicarbonate; Fermented feed
Categories
Funding
- Basic Scientific Research Fund Project of Jilin Academy of Agricultural Sciences [KYJF2021JQ103]
- China Postdoctoral Science Foundation [2020M681063]
- Scientific Research Institutes of Jilin Province
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Sodium bicarbonate pretreatment and solid-state fermentation were used to enhance the nutritional value of corn germ meal (CGM) by inoculating it with Bacillus velezensis CL-4, which has the ability to degrade lignocellulose. The pretreated and fermented CGM showed increased protein content and improved degradation of cellulose and hemicellulose. Electron microscopy revealed changes in the structure of the CGM substrate, indicating lignocellulose breakdown. Important metabolites were identified during the pretreatment process. These findings highlight the potential of using B. velezensis CL-4 for lignocellulosic biological feed production.
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.
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