Microbiological and Biochemical Properties in Eutric/Dystric Brunic Arenosols, Eutric/Endocalcaric Cambisols, and Haplic/Albic Luvisols Soils

Abstract

To understand the role of microorganisms in the functioning of forest ecosystems, the structure of bacterial communities and the enzymatic activity were determined in forest soils representing the following soil subtypes: Eutric/Dystric Brunic Arenosols (A), Eutric/Endocalcaric Cambisols (C), and Haplic/Albic Luvisols (L). Their microbiological and biochemical properties were compared based on bacterial counts and diversity, and activities of seven soil enzymes: dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and β-glucosidase. Organotrophic bacteria and actinobacteria were the most abundant and featured the highest values of the EP (ecophysiological diversity index) in the Haplic/Albic Luvisol soil. In turn, the CD (colony development index) values of these bacterial groups were the highest in the Eutric/Endocalcaric Cambisols. The OTU number of bacteria allowed concluding that, at the class level, the Eutric/Dystric Brunic Arenosols and Haplic/Albic Luvisols were predominated by Alphaproteobacteria belonging to Proteobacteria, whereas the Eutric/Endocalcaric Cambisols by Actinobacteria. At the family rank, the Eutric/Dystric Brunic Arenosols were colonized in the highest numbers by Mycobacteriaceae, Rhodospirillaceae, Koribacteriaceae, and Acidobacteriaceae; the Eutric/Endocalcaric Cambisols by Nocardiaceae, Bradyrhizobiaceae, and Mycobacteriaceae, whereas Haplic/Albic Luvisols by Sinobacteriaceae and Rhodospirillaceae. Four bacterial genera, i.e., Rhodoplanes, Burkholderia belonging to Proteobacteria, Mycobacterium belonging to Actinobacteria, and Candidatus Solibacter belonging to Acidobacteria, were identified in all soils tested. The genetic diversity of bacteria was proved the highest in Eutric/Endocalcaric Cambisols. In turn, the highest enzymatic activity was found for Haplic/Albic Luvisols, while the lowest one for Eutric/Endocalcaric Cambisols. The present study results point out to significant differences between the soil types analyzed in terms of the diversity and structure of their bacterial communities and their enzymatic properties.