Atmospheric Methane Consumption by Forest Soils and Extracted Bacteria at Different pH Values
Atmospheric Methane Consumption by Forest Soils and Extracted Bacteria at Different pH Values
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DOI：
10.1128/aem.64.7.2397-2402.1998
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发表时间：
1998-07
影响因子：
4.4
通讯作者：
J. A. Amaral;T. Ren;R. Knowles
中科院分区：
文献类型：
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作者：
J. A. Amaral;T. Ren;R. Knowles
本文用森林土壤泥浆和从同一土壤中提取的细菌研究了pH对大气甲烷（CH 4）消耗的影响。土壤样本采集自新罕布什尔州的混合硬木林、马尼托巴北方汤普森附近BOREAS（北方生态系统大气研究）站点的短叶松和白杨林、魁北克南部站点（包括山毛榉林和草地）以及安大略站点（栽培腐殖土）。在酸性（pH 4.5至5.2）和碱性（pH 7.2至7.8）土壤中，大气CH 4（浓度约为1.8 ppm）的消耗发生在>5厘米的深度。在酸性土壤的泥浆中，最大活性发生在不同的pH值（pH 4.0至6.5）。通过高速混合和密度梯度离心从这些土壤中提取的细菌表现出不同的pH响应的泥浆的pH响应。在所有情况下，这些细菌具有5.8的甲烷氧化最适pH，并且在已知甲烷氧化菌的最适pH范围pH 6.8至7.0下不表现出活性。pH响应的这种差异可能有助于修改目前用于分离这些生物体的培养基。在以前不消耗CH 4的土壤中，通过用5%（体积/体积）CH 4（每升50，000 μl CH 4）预培养或用20%CH4液体富集来诱导甲烷氧化活性。细菌显示典型的已知甲烷氧化菌和不典型的环境CH 4的预先存在的消费者的pH响应。此外，甲烷氧化菌诱导的高CH 4水平更容易从土壤中提取比预先存在的环境CH 4消费者。在碱性土壤中，预先存在的活性要么被破坏，要么被所使用的程序抵抗提取。结果支持的假设，消费者的环境甲烷在土壤中的生理不同的甲烷氧化菌。
ABSTRACT The effect of pH on atmospheric methane (CH4) consumption was studied with slurries of forest soils and with bacteria extracted from the same soils. Soil samples were collected from a mixed hardwood stand in New Hampshire, from jackpine and aspen stands at the BOREAS (Boreal Ecosystem Atmosphere Study) site near Thompson, northern Manitoba, from sites in southern Québec, including a beech stand and a meadow, and from a site in Ontario (cultivated humisol). Consumption of atmospheric CH4 (concentration, approximately 1.8 ppm) occurred at depths of >5 cm in both acidic (pH 4.5 to 5.2) and alkaline (pH 7.2 to 7.8) soils. In slurries of acidic soils, maximum activity occurred at different pH values (pH 4.0 to 6.5). Bacteria extracted from these soils by high-speed blending and density gradient centrifugation showed pH responses different from the pH responses of the slurries. In all cases, these bacteria had a methanotrophy pH optimum of 5.8 and exhibited no activity at pH 6.8 to 7.0, the pH optimum range for known methanotrophs. This difference in pH responses could be useful in modifying media currently used for isolation of these organisms. Methanotrophic activity was induced in previously non-CH4-consuming soils by preincubation with 5% (vol/vol) CH4 (50,000 μl of CH4 per liter) or by liquid enrichment with 20% CH4. The bacteria showed pH responses typical of known methanotrophs and not typical of preexisting consumers of ambient CH4. Furthermore, methanotrophs induced by high CH4 levels were more readily extracted from soil than preexisting ambient CH4 consumers were. In the alkaline soils, preexisting activity either was destroyed or resisted extraction by the procedure used. The results support the hypothesis that consumers of ambient CH4 in soils are physiologically distinct from the known methanotrophs.