Institute of Animal Nutrition and Feed, Jilin Academy of Agricultural Sciences, No. 186 Dong Xinghua Street, Gongzhuling, Jilin Province, 136100, People's Republic of China.
Institute of Agro-Food Technology, Jilin Academy of Agricultural Sciences, No. 1366 Cai Yu Street, Changchun, Jilin Province, 130033, People's Republic of China.
Appl Microbiol Biotechnol. 2022 Sep;106(18):6077-6094. doi: 10.1007/s00253-022-12130-7. Epub 2022 Aug 17.
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.
小苏打预处理和固态发酵（SSF）被用于通过接种从鸡盲肠内容物中分离出的能够降解木质纤维素的解淀粉芽孢杆菌 CL-4 来最大限度地提高玉米胚芽粕（CGM）的营养价值。基于基因组测序，解淀粉芽孢杆菌 CL-4 具有 4063558 bp 的环状染色体和 46.27%的 GC 含量。此外，还检测到与木质纤维素降解相关的基因。用小苏打（优化至 0.06 g/mL）预处理 CGM（PCGM）可中和低 pH 值。发酵和预处理的 CGM（FPCGM）比 CGM 和 PCGM 含有更多的粗蛋白（CP）、三氯乙酸可溶性蛋白（TCA-SP）和总氨基酸（aa）。发酵 48 小时后，纤维素和半纤维素的降解率分别降低了 21.33%和 71.35%。通过电子显微镜观察，FPCGM 破坏了 CGM 基质的表面结构，并添加了一些小的木质纤维素碎片。此外，2-氧代己二酸和二甲亚砜是预处理过程中最重要的代谢物。发酵 48 小时后，腺苷、胞苷、鸟苷、S-甲基-5′-硫代腺苷和腺嘌呤的浓度显著降低，而益生菌、酶和脂肪酸（包括棕榈酸、16-羟基棕榈酸和亚油酸）的浓度在发酵后显著提高。总之，CGM 的新型预处理为利用解淀粉芽孢杆菌 CL-4 降解木质纤维素成分、改善 CGM 的营养特性以及扩大 CGM 木质纤维素生物饲料生产提供了概念验证。关键点：• 小苏打（碳酸氢钠）可用作经济环保的添加剂预处理玉米胚芽粕；• 解淀粉芽孢杆菌发酵可降解玉米胚芽粕的纤维素和半纤维素成分，提高其饲料质量；• 作为一种新型合格安全性假定（QPS）菌株，解淀粉芽孢杆菌在食品和饲料工业中具有广泛的潜在应用。
