Studies on rumen methanogens associated with ciliates

研究了瘤胃产甲烷菌的作用和生态位，特别是它们与瘤胃纤毛虫原虫的关系。研究结果表明：(1)与纤毛虫相关的产甲烷菌数量在投喂后显著增加，投喂后3h降至投喂前水平。数量的快速增加和减少表明，根据纤毛虫的代谢活动，存在附着在纤毛虫表面和来自纤毛虫表面的产甲烷种群。在纤毛虫相关种群和非相关种群之间，观察到产甲烷菌对氨的耐受性和对氯化钠的依赖性存在差异。(2)纤毛虫原生动物的表观甲烷产生量具有明显的种属依赖性。等毛藻Isotricha spp.在所测试的属中产生最多的甲烷。而Polyplstron spp.和淫羊藿属(Epiddium spp.)产生了少量的甲烷。(3)产甲烷菌与纤毛虫的关系表现为种间氢转移。测试了这个…是否更多的亲缘关系可以被其他水基因营养细菌所取代。脱硫弧菌。SR3和瘤胃乙酸剂Ser5与瘤胃纤毛虫共培养，消耗氢气。然而，纤毛虫对底物的降解没有明显的刺激作用。(4)从纤毛虫中分离到11株以上产甲烷菌，它们的形态特征基本一致。对1g阳性蚕茧和1g阳性菌棒进行了底物和某些生理特性的进一步测试。这两个分离株都使用氢和甲酸盐作为电子供体。两株菌株对氯化钠的依赖程度和对氨气的耐受性与纤毛虫伴生产甲烷菌群相似，但不同。这些菌株可能不是内共生产甲烷菌，而是附着在纤毛虫表面的产甲烷菌。对这些菌株和纤毛虫伴产甲烷菌进行的DNA分析表明，利用该菌的16SRDNA扩增对纤毛虫的产甲烷菌和纤毛虫中产甲烷菌的遗传差异进行了分析，因为该引物没有扩增出产甲烷菌的产物。较少

Roles and niche or ruminal methanogens were investigated with special reference to their relation to rumen ciliate protozoa. Following points were clarified.(1) Number of methanogens associated with ciliates significantly increased after feeding, then declined to pre-feeding level 3 h after feeding. Rapid increases and decrease in numbers suggested the presence of methanogenic population which attaches on and leaves from ciliate surfaces according to the metabolic activity of ciliates. Difference in ammonia tolerance and sodium chloride dependence of methanogens was observed between ciliate associated and non-associated populations. (2) Apparent methane productions from ciliate protozoa were apparently genus-dependent. Isotricha spp. produced the largest amount of methane among genera tested. While Polyplastron spp. and Epidinium spp. produced small amount of methane. (3) Relation between methanogens and ciliate is characterized as interspecies hydrogen transfer. It was tested if this … More relation could be replaced by other hydrogenotrophic bacteria. Desulfovibrio sp. SR3 and ruminal acetogen Ser 5 established cocultures with rumen ciliates in consuming hydrogen. Substrate degradation by ciliate was not significantly stimulated, however. (4) More than 11 methanogens were isolated from ciliates, most of them had similar morphological features. One gram positive cocoid and one gram positive rod were further tested their substrates and some physiological characteristics. Both isolates used hydrogen and formate as electron donors. Sodium chloride dependence and ammonia tolerance of both isolates were similar and differed from those observed in ciliate associated methanogenic population. These isolates may not be endosymbiotic methanogens but the methanogens attached on the ciliate surfaces. DNA analysis on these isolates as well as ciliate associated methanogenic population by PCR using the primer sets for 16Sr DNA of alchaea suggested the genetical difference of methanogen on and in ciliate from known alchaea, because no amplified product was obtained with this alchaea specific primer set. Less