@misc{DimitrovaRepmannFreese, author = {Dimitrova, Tsvetelina and Repmann, Frank and Freese, Dirk}, title = {Degradation of ferrocyanide by natural isolated bacteria}, series = {International Journal of Phytoremediation}, volume = {22}, journal = {International Journal of Phytoremediation}, number = {1}, issn = {1549-7879}, doi = {10.1080/15226514.2019.1633996}, pages = {20 -- 28}, abstract = {This study aims at investigating the iron cyanide (CN) degradation potential of two natural bacterial isolates with the purpose of their application in iron CN phytoremediation. The strains were isolated from contaminated soil and incubated over 4 months with 50mg L⁻¹CN (as ferrocyanide) as the sole iron and nitrogen source. Unlike previous reports, the study provides control for bacterial growth, biotic and abiotic CN losses. Bacterial growth, CN, ammonium, and nitrate concentrations were monitored regularly. Both strains grew less rapid with iron CN compared with the positive control. However, the growth was diauxic. The CN concentration in the media decreased with 20\% and 25\% respectively, while that in the sterile controls remained stable. Ammonium was detected in the media of both strains implying that a fraction of the initially applied ferrocyanide has been converted. The nitrogen lost from the system evened out with that in the cells at the end of the experiments. These results showed that the investigated strains were undoubtedly able to grow on iron CN as an alternative nitrogen source, but contrary to some previous findings, the iron CN utilization is much slower and takes place only after complete exhaustion of the cellular nitrogen reserves.}, language = {en} } @misc{DimitrovaRepmannFreese, author = {Dimitrova, Tsvetelina and Repmann, Frank and Freese, Dirk}, title = {Detoxification of ferrocyanide in a soil-plant system}, series = {Journal of Environmental Sciences}, volume = {77}, journal = {Journal of Environmental Sciences}, issn = {1001-0742}, doi = {10.1016/j.jes.2018.06.005}, pages = {54 -- 64}, abstract = {The detoxification of iron cyanide in a soil-plant system was investigated to assess the total cyanide extracted fromcontaminated soil and allocated in the leaf tissue ofwillowtrees (Salix caprea). They were grown in soil containing up to 1000 mg/kg dry weight (dw) of cyanide (CN), added as 15N-labeled potassium ferrocyanide and prepared with a new method for synthesis of labeled iron cyanides. CN content and 15N enrichment were monitored weekly over the exposure in leaf tissue of different age. The 15N enrichment in the young and old leaf tissue reached up to 15.197 per milleand 9063 per mille, respectively; it increased significantly over the exposure and with increasing exposure concentrations (p < 0.05). Although the CN accumulation in the old leaf tissue was higher, compared to the young leaf tissue (p < 0.05), the 15N enrichment in the two tissue types did not differ statistically. This indicates a non-uniform CN accumulation but a uniform 15N allocation throughout the leaf mass. Significant differences were detected between the measured CN content and the C15N content, calculated fromthe 15N enrichment (p < 0.05), revealing a significant CN fraction within the leaf tissue, which could not be detected as ionic CN. The application of labeled iron CN clearly shows that CN is detoxified during uptake by the willows. However, these results do not exclude other detoxification pathways, not related to the trees. Still, they are strongly indicative of the central role the trees played in CN removal and detoxification under the experimental conditions.}, language = {en} }