Conventional methods of chromium removal are often insufficient for the remediation of chromium-contaminated natural environments, necessitating the development of alternative strategies. In this paper, we report the isolation of a novel Morganella morganii strain capable of reducing hexavalent chromium to its less-toxic and less-soluble trivalent form. Cr(VI) reduction by this strain was evaluated in both acidic environments and conditions reflecting natural freshwater sources. The isolate achieved equilibrium within 3 h and displayed a specific uptake rate of 24.30 ± 1.67 mg Cr(VI)/g biomass following HCl treatment. Without acid treatment, a reduction of over 90% was recorded within 72 h for an initial Cr(VI) concentration 20 mg/L, corresponding to a Cr(VI) removal capacity of 19.36 ± 1.89 mg/g. Absorption data of acid-treated STB5 biomass most closely followed the Toth and Langmuir models. FTIR results indicate that hydroxyl groups and extracellular or cell membrane polysaccharides may be potential adsorption sites for hexavalent chromium. Our results suggest that the isolate may be used in situ for treatment of polluted freshwater environments. Copyright © Taylor & Francis Group, LLC

This study aims to determine the extent of metal pollution in Lake Yeniçağa (Bolu, Turkey) by investigating the accumulation trends of five metals (Al, Cu, Fe, Ni and Zn) and a metalloid (As) in gills, exoskeleton, hepatopancreas and abdominal muscles of the freshwater crayfish Astacus leptodactylus. Principal component analysis (PCA), cluster analysis (CA), correlation analysis and analysis of variance (ANOVA) were utilised to determine the accumulation profiles of each element over four seasons. The greatest element accumulation was found to occur in the gills. All elements in exoskeletal tissue displayed positive correlations with each other, a similar trend was also observed in the hepatopancreas samples. Strong (r=0.868) and very strong (r=0.960) positive correlations were found between the accumulations of Al and Fe in gills and the exoskeleton, respectively. Correlations in tissue accumulation rates are discussed in the context of metabolic roles and impacts associated with the elements tested. Elemental compositions of Yeniçağa water and sediment samples were also investigated to determine whether the composition of the surrounding environment matches the metal accumulation trends of tissue samples. We demonstrate that, by the criteria set by the United States Environmental Protection Agency, Lake Yeniçağa is heavily polluted in terms of As and Ni.