The decay of cutin and cuticular components by soil nicroorganisms in their natural environment

The cuticular components cellulose and cutin are decomposed in a period of 3-8 months (depending on the season) by soil microorganisms under natural conditions. The cellulose is attacked prior to the cutin layer. The latter is invaded by microorganisms which settle first in the cellulose layer. If purified cutin strips with the cellulose removed, are exposed to the action of soil microorganisms, the degradation also starts from the “inside” of the layer. The progress of degradation depends on the soil used, active garden soil giving the best, and poor sand soil the slowest attack. The degradation of the cutin layers starts with a swelling of the former boundaries of the epidermal cells, then follows the removal of successive sub-layers and finally the detachment of entire subunits from the weakened structure, ultimately leading to a total decay of the structure. The detachment of the lamellae within the cutin layer could be shown in cross sections of the exposed material by electron microscopical examination. Halo-formation around the invading microorganisms, and the lipid accumulation as a result of fatty acid release from the cutin by far-distance decomposition, showed that cutin decay by exo-enzyme action is a widespread property of soil microorganisms.