Freshwater is becoming an increasingly scarce resource in the entire world. An ecologically friendly and cost effective strategy to provide clean water is represented by phytoremediation, which is based on the ability of certain aquatic plants to recycle nutrients. Since the microorganisms that colonize plants are important for growth, the aim of this study was to investigate the plant microbial community functionality as Community-Level Physiological Profiles (CLPP) using EcoPlates™. Duckweed (Lemna minor, L. trisulca, Spiroldelaarrhiza, W. arrhiza) and water were sampled from Laboratory Aquariums of Faculty of Biology, University of Bucharest (Bucharest, Romania) and Lake Văcărești (Bucharest, Romania). The Shannon-Wiener and Simpson's indices indicated a high functional diversity in microbial communities attached to duckweed samples. The response from the Ecoplates showed which substrates support the growth of duckweed associated bacteria and free floating aquatic bacteria respectively. All 31 carbon sources were metabolized by duckweed associated bacteria, and only 12 were utilized by water samples: β-methyl-D-glucosidase, D-galactonic acid γ lactone, D-galacturonic acid L-asparagine, Tween 40, Tween 80, D-manitol, L-serine. A total of six carbon sources were preferred by microorganisms associated with duckweed plants: D-xylose, D-galacturonic acid, Tween 80, D-manitol, 4-hydroxy benzoic acid, glycogen In all the aquatic plant samples, while none preferred i-erythritol, 2-hydroxy benzoic acid, L-phenylalanine, α-cyclodextrin, N-acetyl-Dglucosamine, L-threonine, α-ketobutyric acid, D,L-α-glycerol phosphate and putrescein.
