Editing Petroleum (section)

==== Anaerobic decay ====
In the absence of plentiful oxygen, [[Aerobic organism|''aerobic'' bacteria]] were prevented from decaying the organic matter after it was buried under a layer of sediment or water. However, [[Anaerobic organism|''anaerobic'' bacteria]] were able to reduce [[sulfate]]s and [[nitrate]]s among the matter to [[Hydrogen sulfide|H<sub>2</sub>S]] and [[Nitrogen|N<sub>2</sub>]] respectively by using the matter as a source for other reactants. Due to such anaerobic bacteria, at first, this matter began to break apart mostly via [[hydrolysis]]: [[polysaccharide]]s and [[protein]]s were hydrolyzed to [[simple sugars]] and [[amino acid]]s respectively. These were further anaerobically [[oxidized]] at an accelerated rate by the [[enzyme]]s of the bacteria: e.g., amino acids went through [[oxidative deamination]] to [[amino acid]]s, which in turn reacted further to [[ammonia]] and [[Keto acid|α-keto acids]]. [[Monosaccharide]]s in turn ultimately decayed to [[Carbon dioxide|CO<sub>2</sub>]] and [[methane]]. The anaerobic decay products of amino acids, monosaccharides, [[phenols]] and [[aldehyde]]s combined into [[fulvic acid]]s. [[Fat]]s and [[wax]]es were not extensively hydrolyzed under these mild conditions.<ref name="Schobert-2013" />