Department of Animal Production, University of Nairobi, Kangemi, P.O. Box 29053, Nairobi, 00625, Kenya.
Arch Microbiol. 2022 Sep 8;204(10):608. doi: 10.1007/s00203-022-03187-z.
Methane is a greenhouse gas with disastrous consequences when released to intolerable levels. Ruminants produce methane during gut fermentation releasing it through belching and/or flatulence. To better understand the diversity of methanogens and functional enzymes associated with methane metabolism in dairy cows, 48 samples; 6 rumen fluid and 42 dung samples were collected from Kenyan and Tanzanian farms and were analyzed using shotgun metagenomic approach. Statistical analysis for species frequency, relative abundance, percentages, and P values were undertaken using MS Excel and IBM SPSS statistics 20. The results showed archaea from 5 phyla, 9 classes, 16 orders, 25 families, 59 genera, and 87 species. Gut sites significantly contributed to the presence and distribution of various methanogens (P < 0.01). The class Methanomicrobia was abundant in the rumen samples (~ 39%) and dung (~ 44%). The most abundant (~ 17%) methanogen species identified was Methanocorpusculum labreanum. However, some taxonomic class data were unclassified (~ 6% in the rumen and ~ 4% in the dung). Five functional enzymes: Glycine/Serine hydroxymethyltransferase, Formylmethanofuran-tetrahydromethanopterin N-formyltransferase, Formate dehydrogenase, anaerobic carbon monoxide dehydrogenase, and catalase-peroxidase associated with methane metabolism were identified. KEGG functional metabolic analysis for the enzymes identified during this study was significant (P < 0.05) for five metabolism processes. The methanogen species abundances from this study in numbers/kind can be utilized exclusively or jointly as indirect selection criteria for methane mitigation. When targeting functional genes of the microbes/animal for better performance, the concern not to affect the host animal's functionality should be undertaken. Future studies should consider taxonomically categorizing unclassified species.
甲烷是一种温室气体，如果释放到无法容忍的水平，将会造成灾难性的后果。反刍动物在肠道发酵过程中会产生甲烷，通过打嗝和/或放屁释放出来。为了更好地了解与奶牛甲烷代谢相关的产甲烷菌和功能酶的多样性，从肯尼亚和坦桑尼亚的农场采集了 48 个样本；6 个瘤胃液样本和 42 个粪便样本，并使用鸟枪法宏基因组学方法进行了分析。使用 MS Excel 和 IBM SPSS statistics 20 对物种频率、相对丰度、百分比和 P 值进行了统计分析。结果表明，古菌来自 5 个门、9 个纲、16 个目、25 个科、59 个属和 87 个种。肠道部位显著影响各种产甲烷菌的存在和分布（P<0.01）。类甲烷微菌在瘤胃液样本中丰富（约 39%），在粪便样本中丰富（约 44%）。鉴定出的最丰富（约 17%）产甲烷菌种是 Methanocorpusculum labreanum。然而，一些分类学类别的数据是未分类的（瘤胃液中约 6%，粪便中约 4%）。与甲烷代谢相关的 5 种功能酶：甘氨酸/丝氨酸羟甲基转移酶、甲酰甲硫氨酸四氢叶酸-四氢甲烷蝶呤 N-甲酰转移酶、甲酸脱氢酶、厌氧一氧化碳脱氢酶和过氧化氢酶-过氧化物酶被鉴定出来。本研究中鉴定的酶的 KEGG 功能代谢分析对 5 个代谢过程具有显著意义（P<0.05）。本研究中甲烷菌种类的数量/种类可以单独或联合用作甲烷减排的间接选择标准。在针对微生物/动物的功能基因进行更好的性能时，应注意不要影响宿主动物的功能。未来的研究应考虑对未分类的物种进行分类学分类。
