@article{oai:kanazawa-u.repo.nii.ac.jp:00011139,
 author = {田崎, 和江 and Tazaki, Kazue and Hattori, Tatsuya},
 journal = {The science reports of the Kanazawa University = 金沢大学理科報告},
 month = {Jan},
 note = {Bacterial mineralization processes in the manganese cycle can be traced using manganese oxide (MnOx) nodules and Mn-oxidizing bacteria. A laboratory simulation experiment showed evidence of an organic contribution to manganese precipitation in freshwater at pH 7-8 and in an Eh range from −24 to +200 mV. Glass slides that were kept in a beaker with natural fresh water and river sediments for half a month were found to be coated by a brown material. These manganese nodules were doughnut-shaped holdfasts of colonized bacteria produced under photosynthetic conditions. These manganese mineral formation processes are composed of MnOx precipitation as well as bacterial activity and were studied by optical microscopy, scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy. Atomic absorption was used for the initial chemical analysis of the river water. The water contained high amounts of dissolved manganese whereas the sediments had no manganese oxide minerals as determined by XRD analysis. The well-developed nodules are mainly poorly crystalline manganese oxides that associate with hydrated iron oxides and with a Leptothrix discophora − like bacteria. EDX semi-quantitative analyses of the holdfasts indicated that iron precipitation occurred on the glass slides at an early stage. Manganese precipitation occurred later during the iron precipitation and declined within 11 days. The mobilization and precipitation paths for the dominant manganese in fresh water indicates the possible quick formation of manganese nodules whose appearance is dependent on the specific biochemical environment during oxidation and substitution of Mn2+. Experimental results indicated that these manganese nodules had a biogeochemical origin rather than an inorganic origin in freshwater.},
 pages = {39--54},
 title = {Bacterial Contribution to Precipitation of Manganese Nodules in Freshwater Environments : An E1ectron Microscope Study of Experimental Biomineralization by Cultured Bacteria},
 volume = {53},
 year = {2009}
}