An isolate, designated GC-29, that could incompletely oxidize glucose to ac
etate and carbon dioxide with Fe(III) serving as the electron acceptor was
recovered from freshwater sediments of the Potomac River, Maryland. This me
tabolism yielded energy to support cell growth. Strain GC-29 is a facultati
vely anaerobic, Gram-negative motile rod which, in addition to glucose, als
o used sucrose, lactate, pyruvate, yeast extract, casamino acids or H-2 as
alternative electron donors for Fe(III) reduction. Stain GC-29 could reduce
NO3-, Mn(IV), U(VI), fumarate, malate, S2O32-, and colloidal S-0 as well a
s the humics analog, 2,6-anthraquinone disulfonate. Analysis of the almost
complete 16S rRNA sequence indicated that strain GC-29 belongs in the Shewa
nella genus in the epsilon subdivision of the Proteobacteria. The name Shew
anella saccharophilia is proposed. Shewanella saccharophilia differs from p
reviously described fermentative microorganisms that metabolize glucose wit
h the reduction of Fe(III) because it transfers significantly more electron
equivalents to Fe(III); acetate and carbon dioxide are the only products o
f glucose metabolism; energy is conserved from Fe(LII) reduction; and gluco
se is not metabolized in the absence of Fe(III). The metabolism of organism
s like S, saccharophilia may account for the fact that glucose is metaboliz
ed primarily to acetate and carbon dioxide in a variety of sediments in whi
ch Fe(III) reduction is the terminal electron accepting process. (C) 1998 A
cademic Press.