Putrefaction.—This process goes on best in the absence of oxygen by aid of anaerobic bacteria. Some anaerobic albumin destroyers are Bacillus putrificans, B. paraputrificans, Parapledrum foetidum. Bacillus macerans and B. amijlohacter cause the destruction of pectin substances (plant mucus) and of the hemicelluloses used as reserve and cell-wall materials. The group which ferments cellulose, decomposing it into fatty acids, methane, and hydrogen, includes, according to Dliggeli (1923, p. 16), B. methanicus B.fossicularum, and other species. Putrefactive organisms inhabit the upper soil layer, especially where plant remains have accumulated in large quantities, and where the supply of air is small. Especially favorable conditions occur in the mud of swamps and in the drift peat of lakes and large streams. The mineral substances resulting from humus decomposition in mud occur in a form which cannot be assimilated by plants. (Braun-Blanquet 1932:243)
BRAUN-BLANQUET, Josias. 1932. Plant sociology: the study of plant communities. (Trans.: George D. Fuller; Henry S. Conard) New York: McGraw-Hill Book Company.