Structural and functional microbial diversity along a eutrophication gradient of interconnected lakes undergoing anthropopressure.

We present the results of an analysis of the 16S rRNA-based taxonomical structure of bacteria together with an analysis of carbon source utilization ability using EcoPlate (Biolog, USA) metabolic fingerprinting assessment against the backdrop of physicochemical parameters in fifteen interconnected lakes. The lakes exhibit a wide spectrum of trophic gradients and undergo different intensities of anthropopressure. Sequences of V3-V4 16S rRNA genes binned by taxonomic assignment to family indicated that bacterial communities in the highly eutrophicated lakes were distinctly different from the bacterial communities in the meso-eutrophic lakes (ANOSIM r = 0.

Quantitative description of respiration processes in meso-eutrophic and eutrophic freshwater environments.

We propose a modification of measurement methodology allowing the overall respiration rate (V) close to the in situ conditions; size of the labile, respirable organic matter pool (OM); and its turnover time (Tt) to be calculated. In addition to the respiration of dissolved substrates by free-living bacteria, the respiration of attached bacteria and other planktonic organisms is also taken into account. In case study we evaluated the modified, quantitative description of respiration processes in surface waters of lakes of different trophic status: mezzo-eutrophic and eutrophic.

Coomassie Blue G250 for Visualization of Active Bacteria from Lake Environment and Culture.

Bacteria play a fundamental role in the cycling of nutrients in aquatic environments. A precise distinction between active and inactive bacteria is crucial for the description of this process. We have evaluated the usefulness of Coomassie Blue G250 for fluorescent staining of protein containing potentially highly active bacteria.

Persistence of bacterial proteolytic enzymes in lake ecosystems.

This study analyzes proteolytic enzyme persistence and the role of dead (or metabolically inactive) aquatic bacteria in organic matter cycling. Samples from four lakes of different trophic status were used. Irrespective of the trophic status of the examined lakes, bacterial aminopeptidases remained active even 72 h after the death of the bacteria that produced them.

The dynamics of protein decomposition in lakes of different trophic status--reflections on the assessment of the real proteolytic activity in situ.

Abstract The aim of this paper is to discuss the methodology of our investigation of the dynamics of protein degradation and the total in situ proteolytic activity in meso/eutrophic, eutrophic, and hypereutrophic freshwater environments. Analysis of the kinetics and rates of enzymatic release of amino acids in water samples preserved with sodium azide allows determination of the concentrations of labile proteins (C(LAB)), and their half-life time (T(1/2)). Moreover, it gives more realistic information on resultant activity in situ (V(T(1/2))) of ecto- and extracellular proteases that are responsible for the biological degradation of these compounds.

Urea and ureolytic activity in lakes of different trophic status.

Urea and uraease (U-ase) activity were determined in water samples taken from the surface layers of 17 lakes of different trophic status. Urea concentrations were inversely correlated with the trophic status of the studied lakes and varied from below the detection limit to 25 micromol l(-1). Maximal potential ureolytic activity (V(max)) ranged from 0.