ELBA Bioflux, 2014, Volume 6, Issue 2. www.elba.bioflux.com.ro 94 ELBA BIOFLUX Extreme Life, Biospeology & Astrobiology International Journal of the Bioflux Society Enzymatic activity in soil samples from Gilău and Floreşti transect, Cluj, Romania Rahela Carpa, Marius Mureşanu, Maria C. Maior, Mihai Drăgan-Bularda Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babes-Bolyai University, Cluj-Napoca, Romania. Corresponding author: R. Carpa, k_hella@yahoo.com Abstract. The aim of this paper was to assess the activity of some enzymes from soils of polluted zones in order to understand the complex processes that happen in these habitats of special significance. The sampling sites were 5 zones from Gilău and Floreşti transect. There were established the types of the soil samples collected from different places. In the soil samples the following enzymatic activities have been quantitatively determined: actual and potential dehydrogenase, phosphatase and catalase. The studied activities were detected in all five soil samples, with differences noticed only as regards the intensity of the processes. Based on the absolute values on enzymatic activities, the enzymatic indicator of soil quality (EISQ) was calculated. The EISQ values ranged between 0.05 and 0.27, indicating a low intensity of the enzymatic activities. Key Words: soil type, enzymatic activity, enzymatic indicator of soil quality. Rezumat. Scopul acestei lucrări a constat în determinarea activităţii unor enzime din solurile unei zone poluate cu scopul de a înţelege procesele complexe care au loc în aceste habitate cu importanţă special ă. Au fost prelevate probe din 5 zone cuprinse pe transectul dintre localităţile Gilău şi Floreşti. A fost stabilit tipul de sol al fiecărei probe prelevate. În probele de sol au fost determinate cantitativ următoarele activităţi enzimatice: activitatea dehidrogenazică actuală şi potenţială, activitatea fosfatazică şi activitatea catalazică. Activităţile enzimatice au fost detectate în toate cele 5 probe de sol, cu diferenţe între ele în ceea ce priveşte intensitatea proceselor. Pe baza valorilor absolute a activităţilor enzimatice s-a calculat indicatorul enzimatic de calitate al solurilor (IECS). Valorile IECS au fost cuprinse între 0.05 şi 0.27, indicând o intensitate scăzută a activităţilor enzimatice. Cuvinte cheie: tip de sol, activitate enzimatică, indicatorul enzimatic al calităţii solului. Introduction. Soil enzymes are a group of enzymes found in soil and they are constantly playing an important role in maintaining soil ecology, physical and chemical properties, fertility of soils and contribute to the health of soils. Soil enzyme activities are often closely related to soil organic matter, soil physical properties and microbial activity or biomass, changes quicker than other parameters, thus providing early indications of changes in soil health, and involve simple procedures (Dick et al 2000). In addition, soil enzyme activities can be used as measures of microbial activity, soil productivity, and inhibiting effects of pollutants. Soil enzyme data have constituted the foundation for the development of conceptual models that provide a more comprehensive understanding of those key processes linking microbial populations and nutrient dynamics (Schimel & Weintraub 2003). Soil contamination with heavy metals has become a serious issue all over the world, as a result of wastewater irrigation, sludge application, solid waste disposal, automobile exhaust and industrial activities (Cui et al 2005). Soil enzymes are synthesized by microorganisms and act as biological catalysts to facilitate different reactions and metabolic processes, to decompose organic pollutants and produce essential compounds for both microorganisms and plants (Moreno et al 2003). Soil enzymatic activities are recognized as a more sensitive bio-indicator than plants and animals of any natural and anthropogenic disturbance (Hinojosa et al 2004).