Decomposition of Microbial Cells and Components in Soil and Their Stabilization Through Complexing with Model Humic Acid-Type Phenolic Polymers
1979
Nelson, D. W. | Martin, J. P. | Ervin, J. O.
Axenic cultures of bacteria, yeasts, and filamentous fungi were cultured on ¹⁴C-glucose-peptone medium. Cells were fractionated into cell wall and cytoplasm components and the components were complexed into model phenolic polymers or intimately mixed with preformed polymers prior to incubation in soil. Whole cells, cell walls, and cytoplasm fractions readily decomposed in soil; by 12 weeks of incubation from 50 to 79% of added ¹⁴C had evolved as ¹⁴CO₂. Complexing of cell walls with polymers prepared from hydroxybenzoic acids and from hydroxytoluenes plus phenols reduced decomposition an average of 31 to 56%, respectively. Incorporating cytoplasm components into phenolic polymers reduced decomposition by an average of 49%. Intimately mixing cell walls with preformed polymers prepared from hydroxybenzoic acids and from hydroxytoluenes reduced decomposition an average of 14 and 28%, respectively. Mixing cytoplasm components with preformed polymers reduced decomposition by an average of 11%. Addition of whole cells or cellular components did not increase the decomposition of native soil organic matter. A higher proportion of residual ¹⁴C after incubation was recovered in the humic acid fraction in samples treated with cell walls complexed into phenolic polymers as compared to samples receiving uncomplexed cell walls. The implications of the study with regard to humus formation in soils are discussed.
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