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An electroanalytical method was developed for the determination of the phytohormone indole-3-acetic acid in water using a glassy-carbon electrode. The differential pulse voltammetry was combined with a purification step which involved the extraction of plant tissue and the separation of plant pigments by passing through column Oasis MCX. Indole-3-acetic acid can be determined under optimum conditions with a limit of quantification ( LOQ) 2.7×10−6 mol L−1. The linearity range was from 1.8×10−6 to 6.6×10−4 mol L−1. The electroanalytical determination of indole-3-acetic acid is selective, fast and economic. The presence of other phytohormones as abscisic acid and cytokinins as isopentenyladenine, isopentenyladenosine, trans-zeatin, zeatin riboside does not interfere the determination of indole-3-acetic acid in plant sample. [ABSTRACT FROM AUTHOR]

This explorative study was aimed at first characterizing the sponge Spongilla lacustris (Linnaeus, 1759) from the sub-Arctic Pasvik River (Northern Fennoscandia), in terms of associated microbial communities and pollutant accumulation. Persistent organic pollutants were determined in sponge mesohyl tissues, along with the estimation of the microbial enzymatic activity rates, prokaryotic abundance and morphometric traits, and the analysis of the taxonomic bacterial diversity by next-generation sequencing techniques. The main bacterial groups associated with S. lacustris were Alphaproteobacteria and Gammaproteobacteria, followed by Chloroflexi and Acidobacteria. The structure of the S. lacustris-associated bacterial communities was in sharp contrast to those of the bacterioplankton, being statistically close to those found in sediments. Dieldrin was measured at higher concentrations in the sponge tissues (3.1 ± 0.4 ng/g) compared to sediment of the same site (0.04 ± 0.03 ng/g). Some taxonomic groups were possibly related to the occurrence of certain contaminants, as was the case of Patescibacteria and dieldrin. Obtained results substantially contribute to the still scarce knowledge of bacterial community diversity, activities, and ecology in freshwater sponges. PRACTITIONER POINTS: Microbial community associated with Spongilla lacustris is probably shaped by the occurrence of certain contaminants, mainly dieldrin and heavy metals. A higher accumulation of dieldrin in the sponge mesohyl tissues than in sediment was determined. S. lacustris is suggested as sponge species to be used as a sentinel of pesticide pollution in the Pasvik River. S. lacustris, living in tight contact with soft substrates, harbored communities more similar to sediment than water communities., (© 2024 Water Environment Federation.)