A previously isolated exoelectrogenic bacterium, strain SD-1T, was further characterized and identified as a representative of a novel species of the genus Geobacter. Strain SD-1T was Gram-negative, aerotolerant, anaerobic, non-spore-forming, non-fermentative and non-motile. Cells were short, curved rods (0.8–1.3 µm long and 0.3 µm in diameter). Growth of strain SD-1T was observed at 15–42 °C and pH 6.0–8.5, with optimal growth at 30–35 °C and pH 7. Analysis of 16S rRNA gene sequences indicated that the isolate was a member of the genus Geobacter, with the closest known relative being Geobacter sulfurreducens PCAT (98 % similarity). Similar to other members of the genus Geobacter, strain SD-1T used soluble or insoluble Fe(III) as the sole electron acceptor coupled with the oxidation of acetate. However, SD-1T could not reduce fumarate as an electron acceptor with acetate oxidization, which is an important physiological trait for G. sulfurreducens. Moreover, SD-1T could grow in media containing as much as 3 % NaCl, while G. sulfurreducens PCAT can tolerate just half this concentration, and this difference in salt tolerance was even more obvious when cultivated in bioelectrochemical systems. DNA–DNA hybridization analysis of strain SD-1T and its closest relative, G. sulfurreducens ATCC 51573T, showed a relatedness of 61.6 %. The DNA G+C content of strain SD-1T was 58.9 mol%. Thus, on the basis of these characteristics, strain SD-1T was not assigned to G. sulfurreducens, and was instead classified in the genus Geobacter as a representative of a novel species. The name Geobacter anodireducens sp. nov. is proposed, with the type strain SD-1T ( = CGMCC 1.12536T = KCTC 4672T).
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Funding
This study was supported by the:
King Abdullah University of Science and Technology (KAUST)
(Award KUS-I1-003-13)
China Postdoctoral Science Foundation
(Award 2014T70573 and 2013M541773)
National Science Foundation for Distinguished Young Scholars
(Award 51225802)
Science Fund for Creative Research Groups of the National Natural Science Foundation of China
(Award 51121062)
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