Russell J B, Strobel H J
U.S. Dairy Forage Res. Center, Madison, WI.
J Anim Sci. 1988 Feb;66(2):552-8. doi: 10.2527/jas1988.662552x.
Mixed ruminal bacteria (n = 4) were incubated in anaerobic media for 24 h in vitro with either hay, corn meal, protein hydrolyzate or hydrogen gas as the substrate. The ionophore monensin and the polypeptide antibiotic bacitracin were added to the incubation flasks at concentrations ranging from 0 to 10 or 40 mg/liter. As was expected, monensin decreased methane production, increased the ratio of propionate to acetate and decreased the deamination of amino acids. Monensin had little effect on methane production, however, if hydrogen gas was the fermentation substrate. Bacitracin, another gram-positive antibiotic with a distinctly different cellular target, was somewhat less potent than monensin, but it produced strikingly similar responses. This similarity of fermentation patterns suggested that monensin action in the rumen is probably due to its activity as a gram-positive antibiotic, and that any gram-positive antibiotic not suppressed by resistance may produce fermentation effects similar to those of monensin. The cellular action of monensin as an ionophore in membranes is probably little more than a means of inhibiting sensitive species. Many gram-positive antibiotics have little affect on ciliate protozoa or coccidia.
将混合瘤胃细菌（n = 4）在体外厌氧培养基中，以干草、玉米粉、蛋白水解物或氢气作为底物培养24小时。将离子载体莫能菌素和多肽抗生素杆菌肽以0至10或40毫克/升的浓度添加到培养瓶中。正如预期的那样，莫能菌素降低了甲烷产量，增加了丙酸与乙酸的比例，并减少了氨基酸的脱氨作用。然而，如果以氢气作为发酵底物，莫能菌素对甲烷产量几乎没有影响。杆菌肽是另一种具有明显不同细胞靶点的革兰氏阳性抗生素，其效力略低于莫能菌素，但产生了惊人相似的反应。这种发酵模式的相似性表明，莫能菌素在瘤胃中的作用可能归因于其作为革兰氏阳性抗生素的活性，并且任何未被耐药性抑制的革兰氏阳性抗生素可能产生与莫能菌素相似的发酵效果。莫能菌素作为离子载体在膜中的细胞作用可能只不过是抑制敏感菌的一种手段。许多革兰氏阳性抗生素对纤毛虫原生动物或球虫几乎没有影响。
