Cu(II), Fe(III) and Mn(II) combinations as environmental stress factors have distinguishing effects on Enterococcus hirae

Assessment of health risk related to the ingestion of trace metals through fish consumption in Todos os Santos Bay

This study was carried out to evaluate the concentration of trace elements (As, Cd, Cu, Pb, and Zn) in the muscle of carnivorous fish species from three different areas of Todos os Santos Bay (BTS), Bahia State, Brazil. Trace elements were analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES), and consumption rates advisory for minimizing chronic systemic effects in children and adults were estimated. As concentrations in fish samples from Jiribatuba were higher than legal limits set by FAO, and Cd concentrations in fish from Iguape Bay were high in comparison with FAO and EC. This study provides information about the fish consumption limits, considering the elements concentrations observed in the analyses, in particular As and Cd, necessary for minimizing potential health risks.

Comparative effects of Ni(II) and Cu(II) ions and their combinations on redox potential and hydrogen photoproduction by Rhodobacter sphaeroides

The aim of the present work was the study of comparative effects of Cu(II) and Ni(II) and their mixture on growth, redox potential, hydrogen (H₂) yield and ATPase activity in phototrophic purple bacteria R. sphaeroides MDC6522 from Jermuk mineral spring in Armenia. It was ascertained, that Cu²⁺ and Ni²⁺ have different effects on bacterial specific growth rate: in the presence of 5μM Cu²⁺ growth rate was ~3.2-fold lower in comparison with control (no addition), and increased ~1.5-fold in medium with 5μM Ni²⁺. These changes may be resulted by action of the ions on redox potential (E_h). Low concentrations of Ni²⁺ had an enhancing effect on the E_h drop and H₂ production. The increase of concentration from 1 to 5μM enhanced the stimulatory effect of Ni²⁺. H₂ yield in R. sphaeroides (72h of growth) was enhanced ~3-fold with 5μM Ni²⁺, whereas in the presence of 5μM Cu²⁺ H₂ yield was ~1.2 fold lower in comparison with control. Cu²⁺+Ni²⁺ combinations effects were differed from the effect when ions used separately. When Cu²⁺ and Ni²⁺ were added together, the Ni²⁺ stimulatory effect disappeared, which indicated that heavy metal ions mixture may have different action mechanisms. Moreover, N,N'-dicyclohexylcarbodiimide-sensitive ATPase activity of R. sphaeroides membrane vesicles has been increased in the presence of both ions, but in the presence of Сu²⁺ the influence was feebly marked in comparison with Ni²⁺. The results suggest an interaction between these ions and the F_OF₁-ATPase. Thus, the results obtained point out discrimination between Cu²⁺ and Ni²⁺ and their combinations effects and reveal new regulatory pathways to enhance H₂ yield in R. sphaeroides.