ICP analysis of iron (Fe), cobalt (Co), molybdenum (Mo) and nickel (Ni) in cell pellets of the three methanogen species investigated.

Concentrations are given in ppm g-1 of the dried cell material (10 000 ppm = 1wt%). Blank samples are growth medium samples without added microorganisms and no added trace metal solution. DL = detection limit.浓度以每克干燥细胞物质的ppm（ppm g⁻¹）为单位，且10000 ppm 等同于1质量百分比（wt%）。空白样品为未添加微生物且未添加痕量金属溶液的培养基样品。DL为检测限（detection limit）。