Impact of Heavy Metal Pollution on Soil Bacterial Carbon Metabolism

The aim of the study was to evaluate the long-term impact of heavy metals on soil bacterial metabolism by assessing their capacity to utilize a set of carbon sources. The study area is in the vicinity of the Pb/Zn smelter KCM 2000, South-Central Bulgaria, with considerable Pb, Zn, Cd, Cu, and As pollution. The Biolog Ecoplate approach was used to evaluate the bacterial metabolic activity, expressed by the average well colour development; the bacterial metabolic fingerprints expressed by community-level physiological profiling, and Shannon bacterial functional diversity. The results revealed reduced metabolic activity recorded for bacterial communities inhabiting the heavily polluted soils. The most preferred carbon groups utilized by the bacterial communities were the polymers, followed by carbohydrates and amino acids. Local variability of soil properties, such as inorganic ions, total organic carbon, pH, soil moisture, and soil texture, could modify the effects of heavy metals. This study highlighted that Biolog EcoplateTM is a suitable approach for assessing bacterial functional shifts in relation to long-term soil pollution stress.