Open AccessSphaerotilus natans encrusted with nanoball‐shaped F e( III ) oxide minerals formed by nitrate‐reducing mixotrophic F e( II ) oxidation
Author(s) -
Park Sunhwa,
Kim DongHun,
Lee JiHoon,
Hur HorGil
Publication year - 2014
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/1574-6941.12372
Subject(s) - anoxic waters , mixotroph , nitrate , ferrous , electron acceptor , nitrite , redox , strain (injury) , oxidizing agent , biology , heterotroph , environmental chemistry , inorganic chemistry , bacteria , chemistry , ecology , biochemistry , organic chemistry , anatomy , genetics
Ferrous iron has been known to function as an electron source for iron‐oxidizing microorganisms in both anoxic and oxic environments. A diversity of bacteria has been known to oxidize both soluble and solid‐phase Fe( II ) forms coupled to the reduction of nitrate. Here, we show for the first time Fe( II ) oxidation by Sphaerotilus natans strain DSM 6575 T under mixotrophic condition. Sphaerotilus natans has been known to form a sheath structure enclosing long chains of rod‐shaped cells, resulting in a thick biofilm formation under oxic conditions. Here, we also demonstrate that strain DSM 6575 T grows mixotrophically with pyruvate, Fe( II ) as electron donors and nitrate as an electron acceptor and single cells of strain DSM 6575 T are dominant under anoxic conditions. Furthermore, strain DSM 6575 T forms nanoball‐shaped amorphous Fe( III ) oxide minerals encrusting on the cell surfaces through the mixotrophic iron oxidation reaction under anoxic conditions. We propose that cell encrustation results from the indirect Fe( II ) oxidation by biogenic nitrite during nitrate reduction and that causes the bacterial morphological change to individual rod‐shaped single cells from filamentous sheath structures. This study extends the group of existing microorganisms capable of mixotrophic Fe( II ) oxidation by a new strain, S. natans strain DSM 6575 T , and could contribute to biogeochemical cycles of Fe and N in the environment.