温度对产甲烷菌代谢途径和优势菌群结构的影响

Effect of temperature on methanogens metabolic pathway and structures of predominant bacteria

产甲烷菌是严格厌氧的古菌,由其完成的产甲烷过程通常是厌氧微生物生化代谢中最重要的限速步骤。温度作为影响产甲烷菌的产甲烷速率重要因素,其变化会改变生物环境中的产甲烷的代谢途径和优势菌群分布。目前已知甲烷生物合成有3条途径:乙酸代谢途径、CO2还原途径和甲基营养型途径。理论上乙酸途径生成的甲烷约占甲烷生成总量的2/3,CO2还原产甲烷途径则约占1/3,甲基营养型途径只在少数情况下考虑其影响,例如盐湖。在低温条件下产甲烷菌以利用乙酸代谢为主;在中温条件下,产甲烷途径以乙酸代谢和H2/CO2还原一定比例存在;在高温和超高温条件下,以只利用CO2还原途径的菌群为主。

Methanogens are strictly anaerobic archaea, which not only take part in the methanogenesis procedure but also limit this process. Temperature plays a key role in the anaerobic fermentation. Temperature could not only directly alter the community structure and function of methanogenic archaea,but also affect the supply of substrates for methanogens,which in turn indirectly regulates the pathways of methanogenic archaea.There are three pathway for methanogenesis, and they are started from acetic acid, H2/CO2 and C-1 compound respetively. Acetoclastic methanogenesis accounts for about two-thirds of the total methane production globally, while hydrogenotrophic methanogenesis accounts for about one third. Methanol- and methyl amine-derived methanogensis is restricted in ocean and saline water. Acetoclastic methanogenesis is the predominant methanogenesis at a low temperature, and methane is produced by acetoclastic and hydrogenotrophic＆amp;nbsp;methanogenesis at a medium temperature, while methane is exclusively produced by hydrogenotrophic methanogenesis at a high or ultra-high temperature.