Clostridium fervidus sp. nov., a New Chemoorganotrophic Acetogenic Thermophile

Abstract

Clostridium fervidus sp. nov. was isolated from a hot spring in New Zealand. The cells were strictly anaerobic, gram negative, sporeforming, and sluggishly motile rods (0.65 to 0.75 µ wide and 2 to 3 µm long). The spherical spores were subterminal to terminal and did not distend the sporangium. Lysis of the culture occurred at the onset of stationary phase. The deoxyribonucleic acid guanine-plus-cytosine content was 39 mol%. The temperature optimum was 68°C (range, > 37 and < 80°C), and the pH optimum was 7.0 to 7.5 (range, > 5.5 and < 9.0). Growth occurred on Trypticase peptone (BBL Microbiology Systems) or yeast extract. However, with the exception of serine, which could be catabolized as the sole carbon source, either peptone or yeast extract was essential for the fermentation of carbohydrates including glucose, maltose, mannose, xylan, starch, and pyruvate. Acetate was always the major fermentation end product. CO₂, H₂, and minor quantitites of valerate, butyrate, ethanol, and lactate were also produced. C. fervidus (type strain Rt4-B1T) has been deposited with the American Type Culture Collection (ATCC 43204).