Gracilibacter thermotolerans gen. nov., sp. nov., an anaerobic, thermotolerant bacterium from a constructed wetland receiving acid sulfate water
Yong-Jin Lee1,2, Christopher S. Romanek2,3, Gary L. Mills2, Richard C. Davis4, William B. Whitman1 and Juergen Wiegel1
1 Department of Microbiology, The University of Georgia, Athens,
GA 30602, USA
2 Savannah River Ecology Laboratory, Aiken, SC 29802, USA
3 Department of Geology, The University of Georgia, Athens,
GA 30602, USA
4 Department of Cellular Biology, The University of Georgia,
Athens, GA 30602, USA
Abstract
An obligatorily anaerobic, thermotolerant, asporogenic bacterium, strain
JW/YJL-S1T, was isolated from a sediment sample of a constructed
wetland system receiving acid sulfate water (pH 1.6-3.0). Cells of strain
JW/YJL-S1T were straight to curved rods 0.2-0.4 µm in
diameter and 2.0-7.0 µm in length, and stained Gram-negative. Growth
of strain JW/YJL-S1T was observed at 25-54 °C (no growth
at or below 20 or at or above 58 °C), with an optimum temperature
range for growth of 42.5-46.5 °C. The pH25 °C range
for growth was 6.0-8.25 (no growth at or below pH 5.7 or at or above pH
8.5), with optimum growth at pH 6.8-7.75. The salinity range for growth
was 0-1.5 % (w/v) NaCl, with an optimum at 0-0.5 %. During growth on glucose
the isolate produced acetate, lactate and ethanol as main fermentation
end products. The fatty acid composition was dominated by branched-chain
compounds: i15 : 0, a15 : 0, i16 : 0 and i17 : 0. The G+C content of the
genomic DNA was 42.8 mol% (HPLC). Strain JW/YJL-S1T showed
polymorphism of the 16S rRNA gene. Its closest relative was the thermophilic
Clostridium thermosuccinogenes DSM 5807T (a member of
Clostridium cluster III) (a BLASTN search revealed Clostridium
pascui DSM 10365T to have 92.7 % gene sequence similarity,
the highest value). The inferred phylogenetic trees placed strain JW/YJL-S1T
between Clostridium clusters I/II and III. Based on the morphological
and phylogenetic data presented, JW/YJL-S1T (=DSM 17427T=ATCC
BAA-1219T) is proposed as the type strain of a novel species
in a new genus, Gracilibacter thermotolerans gen. nov., sp. nov.
Correspondence
Juergen Wiegel
jwiegel@uga.edu
SREL Reprint #2996
Lee, Y. J., C. S. Romanek, G. Mills, R. C. Davis, W. B. Whitman and J. Wiegel. 2006. Gracilibacter thermotolerans gen. nov., sp. nov., an anaerobic, thermotolerant bacterium from a constructed wetland receiving acid sulfate water. International Journal of Systematic and Evolutionary Microbiology 56:2089-2093.
