SREL Reprint #2996

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

1Department of Microbiology, The University of Georgia, Athens, GA 30602, USA
2Savannah River Ecology Laboratory, Aiken, SC 29802, USA
3Department of Geology, The University of Georgia, Athens, GA 30602, USA
4Department 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.

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.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).