Alkaline Anaerobic Respiration: Isolation and Characterization of a Novel Alkaliphilic and Metal-Reducing Bacterium
Qi Ye,1 Yul Roh,2 Susan L. Carroll,2 Benjamin Blair,3
Jizhong Zhou,2 Chuanlun L. Zhang,1 and Matthew W.
Fields2,4*
Department of Geology, University of Missouri, Columbia, Missouri1;
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge,
Tennessee2;
Department of Biology, Jacbonville State University, Jacbonville, Alabama3,
and Department of Microbiology, Miami University, Oxford, Ohio4
Received 11 December 2003/Accepted 16 May 2004
Iron-reducing enrichments were obtained from leachate ponds at the U.S.
Borax Company in Boron, Calif. Based on partial small-subunit (SSU) rRNA
gene sequences (approximately 500 nucleotides), six isolates shared 98.90/0
nucleotide identity. As a representative, the isolate QYMF was selected
for further analysis. QYMF could be grown with Fe(llI)-citrate, Fe(lll)-EDTA,
Co(lll)-EDTA, or Cr(Vl) as electron acceptors, and yeast extract and lactate
could serve as electron donors. Growth during iron reduction occurred
over the pH range of 7.5 to 11.0 (optimum, pH 9.5), a sodium chloride
range of 0 to 80 g/liter (optimum, 20 g/liter), and a temperature range
of 4 to 45°C (optimum, approximately 35°C), and iron precipitates
were formed. QYMF was a strict anaerobe that could be grown in the presence
of borax, and the cells were straight rods that produced endospores. Sodium
chloride and yeast extract stimulated growth. Phylogenetic analysis of
the SSU rRNA gene indicated that the bacterium was a low-G+C gram-positive
microorganism and had 96 and 920;0 nucleotide identity with Alkaliphilus
transvaalensis and Alkaliphilus crotonatoxidans, respectively.
The major phospholipid fatty acids were 14:1, 16:1w7c, and 16:0, which
were different from those of other alkaliphiles but similar to those of
reported iron-reducing bacteria. The results demonstrated that the isolate
might represent a novel . metal-reducing alkaliphilic species. The name
Alkaliphilus metalliredigens sp. novo is proposed. The isolation
and activity of metal-reducing bacteria from borax-contaminated leachate
ponds suggest that bioremediation of metal-contaminated alkaline environments
may be feasible and have implications for alkaline anaerobic respiration.
SREL Reprint #2847
Ye, Q., Y. Roh, S.L. Carroll, B. Blair, J. Zhou, C. L. Zhang and M. W. Fields. 2004. Alkaline anaerobic respiration: isolation and characterization of a novel alkaliphilic and metal-reducing bacterium. Applied and Environmental Microbiology 70:5595-5602.
