THE DECOMPOSER MICROORGANISMS IN THE ENVIRONMENT AND THEIR SUCCESSION OF SUBSTRATES

Plant litter decomposition is not a purely chemical or physical process, it is basically a biological one resulting from the diverse activities of microorganisms, protozoa and various other soil organisms like insects and worms. The bacteria and fungi play a very significant role in plant litter decomposition and humus formation. The fungi which colonized decaying substrates could use only simple substrates such as sugars and they referred as sugar fungi. Garrett suggested that the root infecting fungi open the way for a sequence of saprophytic sugar fungi, cellulose decomposers and finally lignin decomposers. The initial rates of losses of differrent components could be ranked as sugar > hemicelluloses> cellulose> lignin. During this succession, the substrates were found to become progressively depleted. This biochemically based succession was believed to be reflected in a taxonomic way as the Phycomycetes to be considered as sugar fungi, the Ascomycetes and Deuteromycetes as cellulolytic and finally Basidiomycetes as lignin decomposers.