Response of indigenous Cd-tolerant electrochemically active bacteria in MECs toward exotic Cr（VI） based on the sensing of fluorescence probes

Electrochemically active bacteria （EAB） on the cathodes of microbial electrolysis cells （MECs） can remove metals from the catholyte, but the response of these indigenous EAB toward exotic metals has not been examined, particularly from the perspective of the co-presence of Cd（II） and Cr（VI） in a wastewater. Four known indigenous Cd-tolerant EAB of Ochrobactrum sp X l, Pseudomonas sp X3, Pseudomonas delhiensis X5, and Ochrobactrum anthropi X7 removed more Cd（II） and less Cr（VI） in the simultaneous presence of Cd（II） and Cr（VI）, compared to the controls with individual Cd（II） or single Cr（VI）. Response of these EAB toward exotic Cr（VI） was related to the associated subcellular metal distribution based on the sensing of fluorescence probes. EAB cell membrane harbored more cadmium than chromium and cytoplasm located more chromium than cadmium, among which the imaging ofintracelluler Cr（III） ions increased over time, contrary to the decreased trend for Cd（II） ions. Compared to the controls with single Cd（II）, exotic Cr（VI） decreased the imaging of Cd（II） ions in the EAB at an initial 2 h and negligibly affected therealier. However, Cd（II） diminished the imaging of Cr （III） ions in the EAB over time, compared to the controls with individual Cr（VI）. Current accelerated the harboring of cadmium at an initial 2 h and directed the accumulation of chromium in EAB over time. This study provides a viable approach for simultaneously quantitatively imaging Cd（II） and Cr （III） ions in EAB and thus gives valuable insights into the response of indigenous Cd-tolerant EAB toward exotic Cr（VI） in MECs.

Systematic and long-term technical validity of toxicity determination and early warning of heavy metal pollution based on an automatic water-toxicity-determination-system

Water toxicity determination with electrochemically active bacteria(EAB)shows promise for providing early warnings for heavy metal pollution in water.However,thus far,only idealized tests with a few types of heavy metals have been conducted.In this study,an automatic water-toxicitydetermination system with high technical maturity was established,and the toxicological properties of common heavy metals were systematically assessed.The results demonstrated that the common heavy metals linearly inhibited EAB currents in the range of 0.1 mg/L to 0.5 mg/L.The toxicity ranking of the tested heavy metals was Pb^(2+)>Tl^(3+)>Cu^(2+)>Cd^(2+)>Zn^(2+)>Ni^(2+)>Hg^(2+)>As^(3+).The toxicity interaction mainly exhibited an antagonistic effect in binary heavy metal mixtures.The system can accurately determine surface water toxicity and rapidly monitor heavy metal pollution,with good repeatability and a long lifetime.Overall,this study demonstrates that EAB are capable of long-term(>60 d)surface water quality monitoring and on-site early warning of heavy metal pollution.

Living electronics

Living electronics that converges the unique functioning modality of biological and electrical circuits has the potential to transform both fundamental biophysical/biochemical inquiries and translational biomedical/engineering applications.This article will review recent progress in overcoming the intrinsic physiochemical and signaling mismatches at biological/electronic interfaces,with specific focus on strategic approaches in forging the functional synergy through:(1)biohybrid electronics,where genetically encoded bio-machineries are hybridized with electronic transducers to facilitate the translation/interpretation of biologically derived signals;and(2)biosynthetic electronics,where biogenic electron pathways are designed and programmed to bridge the gap between internal biological and external electrical circuits.These efforts are reconstructing the way that artificial electronics communicate with living systems,and opening up new possibilities for many cross-disciplinary applications in biosynthesis,sensing,energy transduction,and hybrid information processing.