Jr. Bargar et al., In situ characterization of Mn(II) oxidation by spores of the marine Bacillus sp strain SG-1, GEOCH COS A, 64(16), 2000, pp. 2775-2778
Microbial oxidation of Mn(II) and subsequent precipitation of insoluble, re
active Mn(IV) oxides are primary sources of these solid phases in the envir
onment and key controls on Mn cycling in natural waters. We have performed
in situ x-ray absorption near-edge structure (XANES) spectroscopic measurem
ents of Mn(II) oxidation by spores of the marine Bacillus sp. strain SG I t
o characterize the intermediates and products of the oxidation reactions. M
n(IV)-oxides resembling delta-MnO2 were observed to form at a rapid rate (w
ithin 14 min of reaction onset). Mn(III) intermediates did not occur above
detection limit (5 to 10% of total Mn), even though Mn(III)/(II,III) oxides
(MnOOH or Mn3O4) should have been more stable than MnO2 under the conditio
ns of the experiments. These results suggest that Mn(IV) is the primary pro
duct of bacterial Mn(II) oxidation by Bacillus strain SG-1. Given that SG-1
is a good model for Mn(II)-oxidizing bacteria, these findings help to expl
ain the predominance of Mn(IV)-oxides in aquatic environments. Copyright (C
) 2000 Elsevier Science Ltd.