Anaerobic bacterial degradation of pristenes and phytenes in marine sediments does not lead to pristane and phytane during early diagenesis

► Metabolism of pristenes and phytenes by anaerobic bacteria was investigated. ► These isoprenoid alkenes were quickly metabolized by marine bacteria. ► Hydration plays a key role in the degradation of these compounds. ► Pristane and phytane were not detected in the reaction products. ► Biohydrogenation seems to be inefficient for isoprenoid alkenes.