ORIGINAL ARTICLE Enzyme Production During Composting of Aliphatic–Aromatic Copolyesters in Organic Wastes Stanislava Vobe ˇ rkova ´, 1, * Magdalena Da ´ ria Vaverkova ´, 2 and Dana Adamcova ´ 2 1 Faculty of Agronomy, Institute of Chemistry and Biochemistry, Mendel University in Brno, Brno, Czech Republic. 2 Department of Applied and Landscape Ecology, Faculty of Agronomy, Mendel University in Brno, Brno, Czech Republic. Received: October 15, 2015 Accepted in revised form: July 4, 2016 Abstract Monitoring of various enzymes’ production throughout the process provides useful information on the dynamics of composting and is beneficial for understanding the transformations occurring during composting. In this study, aliphatic–aromatic copolyesters with different polyethylene terephthalate/poly(lactic) acid ratios were subjected to laboratory-scale and full-scale composting conditions. Activities of hydrolase (urease, protease, lipase, and cellulase) and dehydrogenase were monitored during 21 days to better understand the effect of polymer presence on enzyme production. After 7 days, a significant increase in lipase, protease, and cellulase activities in compost soil with polymer indicates qualitative and quantitative changes in the content of particular organic polymers, probably due to polymer degradation. This observation was more pronounced for copolyesters A and B and also for reference material—model aromatic oligomer. This result is in correlation with dehydrogenase activity, which reflected a higher microbial growth in compost soil containing polymer. Production of all monitored enzymes was significantly higher in a real compost pile when compared to laboratory composting conditions. Keywords: aliphatic–aromatic copolyester; composting; enzymatic activities; organic fraction of municipal solid wastes Introduction P lastics have become an important environmental issue and their degradability is widely studied in different environments (Karamanlioglu and Robson, 2013; Deroine ´ et al., 2014). Composting serving to biological stabilization of solid or- ganic wastes is commonly considered as one of the most ef- fective ways for polymer biodegradation due to microbial action in aerobic conditions (Garcıa ´-Go ´mez et al., 2005). However, bacteria and fungi occurring in compost do not have the ability to transport polymeric macromolecules directly into cytoplasm. Extracellular enzymes are the primary means, by which microbes degrade the insoluble macromolecules to smaller subunits before they can be taken up and metabolized by the microbial cells (Awasthi et al., 2015). These enzymes can exist in bound or free form within the compost. On the basis of the specific nature of the residual materials in compost, particular enzymatic features will be more significant in the biodegradation reactions. Nevertheless, general enzymatic systems involved in the transformation of main polymeric macromolecules always take part in the process. Conse- quently, metabolic activities, such as protein degradation, lipid modification, or even lignocellulose transformation, are asso- ciated with the composting process in relation to whatever the properties of the starting material are, since they are of uni- versal distribution (Lo ´pez-Gonza ´lez et al., 2014). Thus, enzymatic activity was explored as a possible tool for composting process characterization (Mondini et al. , 2004), and a high proportion of biodegradable matter may sustain high microbial activity (Gomez et al., 2006). Important enzymes involved in the composting process include the following: de- hydrogenases, constituting an indicator of oxidation of simple organic sources of carbon and of respiratory activity of micro- organisms, proteases, and ureases that participate in minerali- zation of nitrogen, and cellulases, which depolymerize cellulose and lipases, which are related to biodegradation of fats. Thus, enzymatic activities could apparently give interesting infor- mation on the rate of decomposition of organic matter and, therefore, on the product stability ( Jurado et al., 2014). A number of studies have focused on the monitoring of the enzyme activities as an indicator of the dynamic decomposi- tion of agricultural wastes (Cayuela et al., 2008; Jurado et al., 2014). However, to date, only a few reports give evidence of the influence of polymer presence in compost on enzyme ac- tivities (Yang et al., 2004). It is therefore conceivable that the enzymatic approach may significantly contribute to knowledge of the biochemical factors controlling the polymer biodegra- dation and may greatly help in optimization of this process. *Corresponding author: Faculty of Agronomy, Institute of Chemistry and Biochemistry, Mendel University in Brno, Zeme ˇ- de ˇlska ´ 1/1665, Brno 613 00, Czech Republic. Phone: +420 545133279; Fax: +420 545212044; E-mail: stanislava.voberkova@ mendelu.cz ENVIRONMENTAL ENGINEERING SCIENCE Volume 00, Number 00, 2016 ª Mary Ann Liebert, Inc. DOI: 10.1089/ees.2015.0445 1