CLOSTRIDIUM-THERMOALCALIPHILUM SP-NOV, AN ANAEROBIC AND THERMOTOLERANT FACULTATIVE ALKALIPHILE

An anaerobic and thermophilic alkaliphile, strain JW/YL23-2T (T = type strain), was isolated from sewage sludge obtained from a sewage plant in Atlanta, Ga. At pH 10.1 and 50-degrees-C, the doubling time of this strain was 19 min. Strain JW/YL23-2T, a motile rod-shaped bacterium with 2 to 12 peritrichous flagella, exhibited a negative Gram stain reaction but was gram-type positive as judged by the polymyxin B test. No heat-stable (85-degrees-C, 15 min) endospores were detected. At 50-degrees-C, growth occurred at pH values ranging from 7.0 to 11.0; the optimum pH was 9.6 to 10.1. The temperature range for growth ranged from 27 to 57.5-degrees-C; the optimum temperature was 48 to 51-degrees-C (pH 10.1). Dissimilatory sulfate reduction was not detected. The organism utilized glucose, fructose, sucrose, maltose, cellobiose, and Casamino Acids. The DNA G + C content was 32 mol% (as determined by chemical analysis). A 16S rRNA sequence analysis revealed a 2% inferred evolutionary distance to Clostridium paradoxum. However, the cell wall type of strain JW/YL23-2T Was A4beta (L-Orn-D-Asp), while that of C paradoxum was A1tau (m-diaminopimelic acid direct). On the basis of the alkaline pH values and high temperatures for optimal growth, the inability to form spores, and other characteristics different from C paradoxum characteristics, strain JW/YL-23-2 was placed in a new species, Clostridium thermoalcaliphilum; JW/YL23-2 (= DSM 7309) is the type strain of this new species.