Total and immobilized enzymatic activity of organic materials before and after composting

• Published in: Compost science & utilization Vol. 15; no. 2; pp. 93 - 100
• Main Authors: Moreno, J.L, Jindo, K, Hernandez, T, Garcia, C
• Format: Journal Article
• Language: English
• Published: Emmaus,PA Taylor & Francis 01.03.2007; JG Press; Taylor & Francis Ltd
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Biological treatment of sewage sludges and wastes; Biotechnology; Chemicals; Composting; composts; Environment and pollution; enzyme activity; Enzymes; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Industrial applications and implications. Economical aspects; MSW composts; Municipal solid waste; Organic contaminants; organic matter; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Plant growth; Proteases; sewage sludge; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Spain; Organic material; Compost; Composting; Enzymatic activity; Waste reuse
• ISSN: 1065-657X; 2326-2397
• DOI: 10.1080/1065657X.2007.10702318

The evaluation of residual organic materials as a source of enzymatic activities immobilized in the humus matrix is a little explored research area, particularly in the case of organic materials derived from municipal wastes. Enzymes catalyze most soil reactions essential for soil functionality. The advantage of humus enzyme-complexes (immobilized enzymes) with regards to free enzymes is that the former are protected in the humic colloid, being more resistant to denaturing agents and other adverse soil conditions. This explains the interest in use of organic wastes (which are produced in an increasingly amount and consequently are economical) as a source of immobilized enzymes, which could be concentrated and used to improve the quality of degraded or contaminated soils. The goal of this study was (i) to assess the potential of sewage sludge (SS) and the organic fraction of municipal solid waste (MSW), as well as their respective composts (CSS and CMSW) as sources of enzymes, (ii) to determine the proportion of such enzymes which are immobilized in the humic matrix of these organic materials, and (iii) to determine the effect of the composting process on the total and the immobilized enzymatic activities of the organic materials. Dehydrogenase (DHA), urease, protease-BAA, alkaline phosphatase (ALP), β-glucosidase (GLA) and o-diphenol oxidase (DPO) activities were determined both in the organic materials and in their humic extracts (except DHA). Sewage sludge had the highest total values of urease, protease-BAA, ALP and DHA activity (12.7 μol NH 4 + -N g −1 h −1 , 40.6 μmol NH 4 + -N g −1 h −1 , 75.7 μmol PNP g −1 h −1 and 0.3 μmol INTF g −1 h −1 , respectively), which decreased with composting, but MSW had the highest total value of DPO activity. For both organic materials, a low percentage of total enzymatic activities were linked to humus (0.6-22%), except in the case of DPO activity. The SS and MSW composting process had a positive effect on the urease, protease-BAA, DPO and ALP immobilization in the humic matrix, as reflected by the higher immobilized activity/total activity ratios in the compost than in the fresh materials.