THE MICROBIOLOGICAL POPULATION OF PEAT

Abstract

The idea prevalent in some quarters that peat bogs are sterile below the surface is shown to be wrong. An abundant population consisting of bacteria and, in the case of certain lowmoor peats, of actinomyces was found at all depths of the peat profiles. In the highmoor peats, the sphagnum layers contain only a relatively limited bacterial population. Below these layers, however, or as soon as the forest, sedge, or sedimentary layers of the peat are reached, there is a great increase in bacterial numbers. Those found in the lower depths of the highmoor peat profiles are autochthonous, or native to their medium. They find in the anaerobic system of those peats as natural a substrate as the aerobic bacteria find in soil or elsewhere, where free O is admitted. The fact that the greatest numbers of bacteria were found in those layers where the greatest decomposition had taken place indicates that these bacteria are largely concerned with the process of decomposition. The existence of cellulose-decomposing bacteria has been established not only in lowmoor and forest peats, but also in highmoor peats. In the latter, the reaction is not very favorable for development of these organisms, while the cellulose and hemicelluloses of the sphagnum plants are highly resistant to decomposition by microorganisms. This accounts for the very slow disintegration of the sphagnum plants in the process of peat formation. Although sphagnum plants have only a relatively low N content (about 1% of dry weight), a part of this N will be liberated as NH2 when decomposition of the sphagnum plants takes place, as a result of the inability of the microorganisms to attack readily their carbohydrates.