Clostridiurn rjungdahlii sp. nov. strain ATCC 49587T (T = type strain) was isolated from chicken yard waste for its ability to produce ethanol from synthesis gas. This gram-positive, motile, sporeforming rod's metabolism was primarily acetogenic. C. ljungdahZii grew with carbon monoxide, hydrogen and carbon dioxide, ethanol, pyruvate, arabinose, xylose, fructose, or glucose. Methanol, ferulic acid, lactate, galactose, and mannose did not support growth. The G+C content was 22 to 23 mol%. C. ljungduhlii is the first acetogen in clostridial23S rRNA homology group I.

We have reconstituted specific RNA polymerase I transcription from three partially purified chromatographic fractions (termed A, B, and C). Here, we present the chromatographic scheme and the initial biochemical characterization of these fractions. The A fraction contained the RNA polymerase I transcription factor(s), which was necessary and sufficient to form stable preinitiation complexes at the promoter. Of the three fractions, only fraction A contained a significant amount of the TATA binding factor. The B fraction contributed RNA polymerase I, and it contained an essential RNA polymerase I transcription factor that was specifically inactivated in response to a significant decrease in growth rate. The function of the C fraction remains unclear. This reconstituted transcription system provides a starting point for the biochemical dissection of the yeast RNA polymerase I transcription complex, thus allowing in vitro experiments designed to elucidate the molecular mechanisms controlling rRNA synthesis.