土壤大气甲烷氧化菌研究进展

Research progress of atmospheric methane oxidizers in soil

摘要:

摘要:土壤微生物催化是大气中痕量甲烷(约1.8ppmv)氧化的唯一生物途径。目前的研究表明好氧土壤中存在专性和选择性大气甲烷氧化菌2种类型:前者(USCα和USCγ)广泛分布于各种好氧旱地土壤，其甲烷氧化酶对低浓度甲烷亲和力极高，属真正的寡营养型，但至今尚未获得该种类的纯培养菌株。后者属于传统甲烷氧化菌Methylocystis /Methylosinus 属，广泛分布于各种周期性排放高浓度甲烷的土壤环境中。该属大部分菌株含有亲和力不同的2 套甲烷单加氧酶系统，其中的高亲和力甲烷单加氧酶使这些菌株可以在相当长的时间内(＞3个月)保持大气浓度甲烷氧化活性，但其生长和繁殖还需依赖于土壤内部阶段性产生的高浓度甲烷。本文详细阐述了2 类大气甲烷氧化菌的发现历程及其可能的生存策略，最后系统梳理了几种关键的环境因子(土壤温度及湿度、土壤pH、植被、土地利用及氮输入)对大气甲烷氧化菌群落结构和甲烷氧化活性的影响，提出并展望了土壤大气甲烷氧化菌研究的重要方向。

Abstract:

Abstract:Microbial oxidation in soil is the only biological sink for atmospheric methane (about 1.8ppmv)．Two groups of atmospheric methane oxidizing bacteria are existed in aerobic soils: obligate and alternative atmospheric methane oxidizing bacteria．The former，such as upland soil cluster α (USCα) and upland soil cluster γ (USCγ)，are widely distributed in a variety of aerobic upland soils，and their particulate methane monooxygenase (pMMO) have very high affinity for methane in low concentration． Bacteria in this group are probably genuine oligotr6ophs．However，so far，there is still no cultivated strain of this group．The latter (Methylocystis/Methylosinus) belongs to traditional methane-oxidizing bacteria，and are widely distributed in soil environments with periodic high methane emission． Most strains of these two genera are known to possess two pMMO isozymes with low and high affinity to methane respectively，and these strains can keep atmospheric methane oxidizing activity for relative long periods (＞3 months) relying on the high affinity pMMO (pMMO2)．However，the growth and reproduction of bacteria in this group are still dependent on endogenous highconcentration methane which is periodically produced within the soils． We reviewed the research progress of these two groups of atmospheric methane-oxidizing bacteria，their possible living strategies，and the effects of several key environmental factors (e.g.soil temperature and moisture，soil pH，vegetation，land use，nitrogen input) on their community composition and methane oxidizing activity．Several important research directions of atmospheric methane oxidizing bacteria have also been proposed.