Data_Sheet_1_Comparative analysis of macroalgae supplementation on the rumen microbial community: Asparagopsis taxiformis inhibits major ruminal methanogenic, fibrolytic, and volatile fatty acid-producing microbes in vitro.pdf

Seaweeds have received a great deal of attention recently for their potential as methane-suppressing feed additives in ruminants. To date, Asparagopsis taxiformis has proven a potent enteric methane inhibitor, but it is a priority to identify local seaweed varieties that hold similar properties. It is essential that any methane inhibitor does not compromise the function of the rumen microbiome. In this study, we conducted an in vitro experiment using the RUSITEC system to evaluate the impact of three red seaweeds, A. taxiformis, Palmaria mollis, and Mazzaella japonica, on rumen prokaryotic communities. 16S rRNA sequencing showed that A. taxiformis had a profound effect on the microbiome, particularly on methanogens. Weighted Unifrac distances showed significant separation of A. taxiformis samples from the control and other seaweeds (p < 0.05). Neither P. mollis nor M. japonica had a substantial effect on the microbiome (p > 0.05). A. taxiformis reduced the abundance of all major archaeal species (p < 0.05), leading to an almost total disappearance of the methanogens. Prominent fiber-degrading and volatile fatty acid (VFA)-producing bacteria including Fibrobacter and Ruminococcus were also inhibited by A. taxiformis (p < 0.05), as were other genera involved in propionate production. The relative abundance of several other bacteria including Prevotella, Bifidobacterium, Succinivibrio, Ruminobacter, and unclassified Lachnospiraceae were increased by A. taxiformis suggesting that the rumen microbiome adapted to an initial perturbation. Our study provides baseline knowledge of microbial dynamics in response to seaweed feeding over an extended period and suggests that feeding A. taxiformis to cattle to reduce methane may directly, or indirectly, inhibit important fiber-degrading and VFA-producing bacteria.

近年来，海藻作为反刍动物甲烷抑制型饲料添加剂的潜力受到广泛关注。截至目前，珊瑚藻（Asparagopsis taxiformis）已被证实是一种强效的肠道甲烷抑制剂，但优先任务是筛选出具备类似特性的本土海藻品种。至关重要的是，任何甲烷抑制剂均不得损害瘤胃微生物组的功能。本研究采用瘤胃体外发酵模拟系统（RUSITEC）开展体外实验，评估三种红藻——珊瑚藻（A. taxiformis）、软膜藻（Palmaria mollis）和日本叉形藻（Mazzaella japonica）——对瘤胃原核生物群落的影响。16S rRNA测序结果显示，珊瑚藻对微生物组具有显著影响，尤其是对产甲烷古菌。加权UniFrac距离分析显示，珊瑚藻组样本与对照组及其他海藻组样本存在显著分离（p<0.05）。软膜藻和日本叉形藻均未对微生物组产生显著影响（p>0.05）。珊瑚藻可降低所有主要古菌的丰度（p<0.05），几乎完全消除了产甲烷古菌。包括纤维杆菌属（Fibrobacter）和瘤胃球菌属（Ruminococcus）在内的主要纤维降解菌与挥发性脂肪酸（VFA）产生菌均受到珊瑚藻的抑制（p<0.05），其他参与丙酸生成的菌属也受到同样影响。珊瑚藻可提升普雷沃氏菌属（Prevotella）、双歧杆菌属（Bifidobacterium）、琥珀酸弧菌属（Succinivibrio）、瘤胃杆菌属（Ruminobacter）以及未分类毛螺菌科（Lachnospiraceae）等多种细菌的相对丰度，表明瘤胃微生物组可适应初始的环境扰动。本研究为长期饲喂海藻后的微生物动态变化提供了基础认知，并表明通过给牛饲喂珊瑚藻以减少甲烷排放，可能会直接或间接抑制重要的纤维降解菌与挥发性脂肪酸产生菌。