An ethanol-utilizing Fe(III)-reducing bacterial strain, OSK2A
T, was isolated from a lotus field in Aichi, Japan. Phylogenetic analysis of the 16S rRNA gene sequences of OSK2A
T and related strains placed it within
Geobacter sulfurreducens PCA
T. Strain OSK2A
T was shown to be a Gram-negative, motile, rod-shaped bacterium, strictly anaerobic, 0.76−1.65
µm long and 0.28−0.45 μm wide. Its growth occurred at 20−40℃, pH 6.0−8.1, and it tolerated up to 1% NaCl. The G+C content of the genomic DNA was 61.2 mol% and DNA-DNA hybridization value with
Geobacter sulfurreducens PCA
T was 60.7%. The major respiratory quinone was MK-8. The major fatty acids were 16:1 ω7
c, 16:0, 14:0, 15:0 iso, 16:1 ω5
c, and 18:1 ω7
c. Strain OSK2A
T could utilize H
2, ethanol, acetate, lactate, pyruvate, and formate as substrates with Fe(III)-citrate as electron acceptor. Amorphous Fe(III) hydroxide, Fe(III)-NTA, fumarate, malate, and elemental sulfur were utilized as electron acceptors with either acetate or ethanol as substrates. Results obtained from physiological, DNA-DNA hybridization, and chemotaxonomic tests support genotypic and phenotypic differentiation of strain OSK2A
T from its closest relative. The isolate is assigned as a novel subspecies with the name
Geobacter sulfurreducens subsp.
ethanolicus, subsp. nov. (type strain OSK2A
T=DSMZ 26126
T=JCM 18752
T).
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