Bacteria derived bioactive compounds: A valuable tool for the electrochemical detection of arsenic (III) ions in contaminated water

• Development of Bioactive Compound-Based Electrochemical Sensors : A simple, fast, and cost-effective electrochemical approach is demonstrated for selective and quantitative detection of As(III) ions in water using bioactive compounds from Bacillus species. • Enhanced Detection in Harsh Conditions : Functionalization of gold electrodes with these bioactive compounds results in stable sensors capable of detecting As(III) in water across a range of pH values (6.5-8.5) and in the presence of competing ions such as Al³⁺, Bi³⁺, Ni²⁺, and Pb²⁺. • Ultra-Low Limits of Detection : The sensors exhibit very low limits of detection (0.19 nM for SPGE-EPS-B3-15 and 0.03 nM for SPGE-BS-SBP3), well below legal limits for arsenic in drinking water (10 µg/L). • Molecular Insight Through MD and DFT Studies : Molecular dynamics (MD) and density functional theory (DFT) studies reveal the key role of microbial peptides, such as polyglutamic acid and Surfactin, in As(III) coordination, confirming the superior detection ability of these bioactive compounds. A simple, fast and cost-effective electrochemical approach is here reported for the selective and quantitative detection of arsenic (III) ions in water starting from bacteria derived bioactive compounds . The exopolysaccharide (EPS B3-15) produced by the thermophilic, heavy metal tolerant Bacillus licheniformis B3-15, and the biosurfactant obtained from Bacillus horneckiae SBP3 (BS- SBP3) were used as sensitive elements for the electrochemical detection of As 3+ due to their known recognition abilities towards this toxic ion, their thermophilic properties and stability in harsh conditions. The covalent functionalization of screen-printed gold electrodes (SPGE) with these bioactive compounds demonstrated to be advantageous to selectively detect As 3+ in contaminated waters. Electrochemical measurements, performed for the developed sensors SPGE-EPS-B3-15 and SPGE-BS- SBP3, at the normal range of pH in surface water systems (6.5–8.5) demonstrated a higher sensitivity towards As 3+ with respect to the bare electrode, also in the presence of other competing ions, such as Al 3+ , Bi 3+ , Ni 2+ and Pb 2+ ,with very low limits of detection (0.19 nM for SPGE-EPS-B3-15 and 0.03 nM for SPGE-BS- SBP3), which are below the legal limits for these heavy metal ions in drinking water (10 μg/L). The reported sensitivity was 1.8 µA nM −1 cm −2 for SPGE-EPS-B3-15 and 17.5 µA nM −1 cm −2 for SPGE-BS- SBP3. The preferred detection abilities of the chosen bioactive compounds towards As 3+ ions have been also confirmed by complete conformational analysis, using a combination of Molecular Dynamics (MD) and Density Functional Theory (DFT) studies.