脱脂辣木籽提取物成分分析及其对体外瘤胃发酵和细菌群落结构的影响

Composition Analysis of Defatted Moringa oleifera Seed Extracts and Their Effects on Rumen Fermentation and Bacterial Community Structure in Vitro

本试验旨在研究脱脂辣木籽提取物成分组成及其对体外瘤胃发酵和细菌群落结构的影响。试验采用脱脂辣木籽粉为试验材料,通过液相色谱-质谱(LC-MS)法测定乙醇相和水相2种提取物的成分差异,并采用体外模拟瘤胃发酵技术,分别设置乙醇和水提取物的添加剂量为0(对照)、1.875、3.750和7.500 mg/kg(n=5),厌氧发酵72 h,测定其对体外瘤胃发酵发酵参数和菌群结构的影响。结果表明:1)脱脂辣木籽乙醇和水提取物的产率分别为12.66%和38.90%;与水提取物相比,乙醇提取物含有较高的类黄酮和异黄酮类化合物,但含有较低的苯类和酚类物质。2)与对照组相比,乙醇提取物添加组干物质降解率显著降低(P<0.05)。3)添加1.875和3.750 mg/kg乙醇提取物培养6 h后,各时间点产气量均显著低于对照组(P<0.05);水提取物添加组各时间点产气量均显著高于对照组(P<0.05)。4)与对照组相比,添加脱脂辣木籽乙醇提取物显著提高了发酵液乳酸含量(P<0.05);添加1.875和3.750 mg/kg乙醇提取物显著提高了发酵液丙酸比例(P<0.05),显著降低了发酵液异丁酸、丁酸、异戊酸、戊酸和己酸比例(P<0.05)。与对照组相比,添加脱脂辣木籽水提取物显著降低了发酵液pH和乙酸比例(P<0.05),显著提高了发酵液乳酸和总短链脂肪酸含量以及丙酸比例(P<0.05);添加1.875和3.750 mg/kg水提取物显著降低了发酵液氨态氮含量和戊酸比例(P<0.05),显著提高了发酵液异戊酸比例(P<0.05)。5)与对照组相比,添加1.875 mg/kg乙醇提取物显著降低了理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)、克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)和毛螺菌科NK3A20群(Lachnospiraceae_NK3A20_group)相对丰度(P<0.05),显著提高了拟杆菌属(Bacteroides)、埃希氏-志贺氏菌属(Escherichia-Shigella)和不动杆菌属(Acinetobacter)相对丰度(P<0.05);而添加3.750 mg/kg水提取物添加显著提高了克里斯滕森菌科R-7群和毛螺菌科NK3A20群相对丰度(P<0.05)。综上所述,脱脂辣木籽乙醇和水提取物营养成分和活性物质含量存在差异,其中,乙醇提取物中的黄酮类物质可能会抑制瘤胃发酵、减少有益菌数量,而水提取物可以促进瘤胃发酵。

This experiment was conducted to study the composition of defatted Moringa oleifera seed extracts and their effects on rumen fermentation and bacterial community structure in vitro.The defatted Moringa oleifera seed powder was used as the material,and the composition difference of two extracts in ethanol phase and water phase was determined by liquid chromatography-mass spectrometry(LC-MS).Using a simulated rumen fermentation technique in vitro,the dosages of ethanol and water extracts were set as 0(control),1.875,3.750 and 7.500 mg/kg(n=5),respectively,and after anaerobic fermentation for 72 h,the effects of defatted Moringa oleifera seed extracts on the fermentation parameters and microflora structure of rumen fermentation in vitro were measured.The results showed as follows:1)the yield of ethanol and water extracts of defatted Moringa oleifera seeds was 12.66%and 38.90%,respectively;compared with the water extract,the ethanol extract contained higher contents of flavonoids and isoflavones,but had lower contents of benzenes and phenols.2)Compared with the control group,the dry matter degradability in ethanol extract supplemental group was significantly decreased(P<0.05).3)After adding 1.875 and 3.750 mg/kg ethanol extract for 6 h,the gas production at all time points was significantly lower than that in the control group(P<0.05);while the gas production in water extract supplemental group was significantly higher than that in the control group at all time points(P<0.05).4)Compared with the control group,the supplementation of defatted Moringa oleifera seed ethanol extract significantly increased the lactic acid content in fermentation broth(P<0.05);the supplementation of 1.875 and 3.750 mg/kg ethanol extract significantly increased the propionate proportion in fermentation broth(P<0.05),and significantly decreased the proportions of isobutyrate,butyrate,isovalerate,valerate and caproate in fermentation broth(P<0.05).Compared with the control group,the supplementation of defatted Moringa oleifera seed water extract significantly decreased the pH and acetate proportion in fermentation broth(P<0.05),and significantly increased the contents of lactic acid and total short-chain fatty acids as well as the propionate proportion in fermentation broth(P<0.05);the supplementation of 1.875 and 3.750 mg/kg water extract significantly decreased the ammonia nitrogen content and valerate proportion in fermentation broth(P<0.05),and significantly increased the isovalerate proportion in fermentation broth(P<0.05).5)Compared with the control group,the supplementation of 1.875 mg/kg ethanol extract significantly decreased the relative abundances of Rikenellaceae_RC9_gut_group,Christensenellaceae_R-7_group and Lachnospiraceae_NK3A20_group(P<0.05),and significantly increased the relative abundances of Bacteroides,Escherichia-Shigella and Acinetobacter(P<0.05);while the supplementation of 3.750 mg/kg water extract significantly increased the relative abundances of Christensenellaceae_R-7_group and Lachnospiraceae_NK3A20_group(P<0.05).In conclusion,there are differences in the contents of nutritional components and active substances between ethanol extract and water extract of defatted Moringa oleifera seeds.Among them,the flavonoids in ethanol extract may inhibit rumen fermentation and reduce the number of beneficial bacteria,while the water extract can promote rumen fermentation.