Natural deep eutectic solvents as biofilm structural breakers.

Natural Deep Eutectic Solvents (NADES) are composed of supramolecular interactions of two or more natural compounds, such as organic acids, sugars, and amino acids, and they are being used as a new media alternative to conventional solvents. In this study, a new application of NADES is presented as a possible technology for biofilm structural breaker in complex systems since the current solvents used for biofilm cleaning and extraction of biofilm components use hazardous solutions. The NADES (betaine:urea:water and lactic acid:glucose:water) were analyzed before and after the biofilm treatment by attenuated total reflection Fourier-transform infrared spectroscopy and fluorescence excitation-emission matrix spectroscopy. Our results indicate that the green solvents could solubilize up to ≈70 percent of the main components of the biofilms extracellular matrix. The solubilization of the biomolecules weakened the biofilm structure, which could enhance the biofilm solubilization and removal. The NADES have the potential to be an environment-friendly, green solvent to extract valuable compounds and break the main structure from the biofilm, leading to a greener method for extracellular polymeric substance (EPS) extraction and biofilm treatment in various water treatment systems.

Accumulation, assimilation and growth inhibition of copper on freshwater alga (Scenedesmus subspicatus 86.81 SAG) in the presence of EDTA and fulvic acid.

Accumulation and growth inhibition of Cu to fresh water alga (Scenedesmus subspicatus 86.81 SAG) and the influences of ethylenediaminetetraacetic acid (EDTA) and fulvic acid (FA) were examined. These results demonstrated that both EDTA and FA could reduce toxicity of Cu to alga by the way of preventing Cu from being adsorbed by cell wall of alga. When dissolved Cu (Cu(dissolved)), extracellular Cu (Cu(extracellular)), and intracellular Cu (Cu(intracellular)) were differentiated, our results showed that the concentration level of extracellular Cu ([Cu(extracellular)]) was a good indicator for measuring the toxic effects of Cu on alga growth in complex matrix. Either in the absence or in the presence of EDTA and FA, the concentration of intracellular Cu increased to 0.6-1.5 x 10(-8) microM per cell when the growth inhibition reached to about 50%. We found that the acute toxicity of copper on unicellular alga could be interpreted by its accumulation at a discrete site or biotic ligand at alga cell wall and critical accumulation of Cu associated with EC(50) was determined to be 1 x 10(-8) microM per cell. Therefore, the Biotic Ligand Model (BML) could be extended to predict the influence of copper on growth inhibition of alga.