FIG 2.

Partial GC-MS selected ion chromatogram (m/z 128 and m/z 174) of an ethylated extract of the methanogenic enrichment cultures amended with C₁₆ to C₂₀ n-alkanes. The presence of five (1-methylalkyl)succinate diethyl esters were identified as (1-methylpentadecyl)succinate diethyl ester (C₁₆), (1-methylhexadecyl)succinate diethyl ester (C₁₇), (1-methylheptadecyl)succinate diethyl ester (C₁₈), (1-methyloctadecyl)succinate diethyl ester (C₁₉) and (1-methylnonadecyl)succinate diethyl ester (C₂₀). These (1-methylalkyl)succinates had been generated by fumarate addition to the n-alkanes hexadecane (C₁₆), heptadecane (C₁₇), octadecane (C₁₈), nonadecane (C₁₉), and eicosane (C₂₀), respectively.