Table_1_Pretreatment of Rapeseed Meal Increases Its Recalcitrant Fiber Fermentation and Alters the Microbial Community in an in vitro Model of Swine Large Intestine.XLSX

The aim of current study was to investigate in an in vitro study how enzymatic and chemical pretreated rapeseed meal (RSM) influences the fiber fermentation and microbial community in the swine large intestine. RSM was processed enzymatically by a cellulase (CELL), two pectinases (PECT), or chemically by an alkaline (ALK) treatment. 16S rRNA gene sequencing data was performed to evaluate changes in the gut microbiota composition, whereas short-chain fatty acid (SCFA) production (ion-chromatography) and non-starch polysaccharides (NSP) composition (using monoclonal antibodies; mAbs) were used to assess fiber degradation. The results showed that ALK, CELL, PECT1, and PECT2 changed microbial community composition, increased the predicted abundance of microbial fiber-degrading enzymes and pathways, and increased acetic acid, propionic acid, butyric acid, and total SCFA production. The increased microbial genera positively correlated with SCFA production. Monoclonal antibody analyses showed that the cell wall polysaccharide structures of RSM shifted after ALK, CELL, PECT1, and PECT2 treatment. The degradation of NSP during the fermentation period was dynamic, and not continuous based on the epitope recognition by mAbs. This study provides the first detailed analysis of changes in the swine intestinal microbiota due to RSM modified by ALK, CELL, PECT1, and PECT2, which altered the microbial community structure, shifted the predicted functional metagenomic profile and subsequently increased total SCFA production. Our findings that ALK, CELL, PECT1, and PECT2 increased fiber degradability in RSM could help guide feed additive strategies to improve efficiency and productivity in swine industry. The current study gave insight into how enzymatic treatment of feed can alter microbial communities, which provides good opportunity to develop novel carbohydrase treatments, particularly in swine feed.

本研究旨在通过体外实验，探究经酶法与化学法预处理的菜籽粕（rapeseed meal, RSM）对猪大肠内纤维发酵及微生物群落的影响。实验中，菜籽粕分别经纤维素酶（cellulase, CELL）、两种果胶酶（pectinases, PECT）进行酶法处理，或经碱性（alkaline, ALK）法进行化学处理。采用16S rRNA基因测序（16S rRNA gene sequencing）技术评估肠道菌群组成的变化；同时通过离子色谱法（ion-chromatography）检测短链脂肪酸（short-chain fatty acid, SCFA）的生成量，并利用单克隆抗体（monoclonal antibodies, mAbs）分析非淀粉多糖（non-starch polysaccharides, NSP）的组成，以此评估纤维降解效果。结果显示，ALK、CELL、PECT1及PECT2处理均可改变菌群群落组成，提升微生物纤维降解酶及代谢通路的预测丰度，并增加乙酸、丙酸、丁酸及总SCFA的生成量。丰度提升的微生物菌属与SCFA生成量呈正相关。单克隆抗体分析结果表明，经ALK、CELL、PECT1及PECT2处理后，菜籽粕的细胞壁多糖结构发生了改变。发酵过程中NSP的降解呈动态变化，并非持续进行，该结论可通过mAbs的表位识别结果得到验证。本研究首次详细分析了经ALK、CELL、PECT1及PECT2改性的菜籽粕对猪肠道菌群的影响：此类处理可改变菌群群落结构，调控预测的功能宏基因组谱，并最终提升总SCFA生成量。本研究发现ALK、CELL、PECT1及PECT2可提升菜籽粕的纤维降解能力，该结果可为饲料添加剂策略提供指导，以提升养猪业的生产效率与产能。此外，本研究阐明了饲料酶法处理如何改变微生物群落，为开发新型碳水化合物酶制剂（尤其是用于猪饲料的酶制剂）提供了良好契机。