Department of Microbiology, University of Washington, Seattle, Washington 98195.
Appl Environ Microbiol. 1984 Jun;47(6):1255-60. doi: 10.1128/aem.47.6.1255-1260.1984.
The distribution of methane and methane-oxidizing bacteria in the water column of Lake Washington was determined monthly for 1 year. The methane profiles were relatively constant, with little stratification and low concentrations (0.05 to 0.5 muM). The number of methane-oxidizing bacteria detected by a filter-plating method was routinely <1/ml throughout the water column, and no incorporation or oxidation of methane was detected by radioisotopic labeling, even after methane was added. However, samples taken from the sediment-water interface contained as much as 3 muM methane and 50 CFU of methane-oxidizing bacteria per ml and showed significant rates of methane oxidation and incorporation. To define the region of maximum activity more precisely, vertical profiles of the sediment were examined. The concentration of methane increased with depth to a maximum of 150 to 325 muM at 2.5 cm, and significant rates of methane oxidation were found within the top 2.5 cm. The apparent K(m)s for methane and oxygen were determined for samples from the top 1.0 cm of the sediment and found to be ca. 10 and 20 muM, respectively. Projected values for methane oxidation rates suggested that maximum methane oxidation occurred in the top 0.5 cm of the sediment.
对华盛顿湖水柱中的甲烷和甲烷氧化菌的分布进行了为期 1 年的每月测定。甲烷分布相对稳定，分层较少，浓度较低（0.05 至 0.5 μM）。通过过滤平板法检测到的甲烷氧化菌数量在整个水柱中常规 <1/ml，即使添加了甲烷，也未检测到甲烷的掺入或氧化。然而，从沉积物-水界面采集的样品含有高达 3 μM 的甲烷和每毫升 50 CFU 的甲烷氧化菌，并且显示出明显的甲烷氧化和掺入速率。为了更精确地定义最大活性区域，检查了沉积物的垂直分布。甲烷浓度随深度增加，在 2.5 厘米处达到最大值 150 至 325 μM，在 2.5 厘米内发现了明显的甲烷氧化速率。从沉积物顶部 1.0 厘米处的样品中确定了甲烷和氧气的表观 Km 值，分别约为 10 和 20 μM。预计的甲烷氧化速率值表明，最大的甲烷氧化发生在沉积物的前 0.5 厘米。
