Clostridium aciditolerans sp. nov., an acid-tolerant spore-forming anaerobic bacterium from constructed wetland sediment

Abstract

An obligately anaerobic, spore-forming, moderately acid-tolerant bacterium, strain JW/YJL-B3T, was isolated from a sediment sample from a constructed wetland system receiving acid sulfate water. Based on 16S rRNA gene sequence analysis, the isolate belonged to the Firmicutes branch with Clostridium drakei SL1T (96.2 % gene sequence similarity) as its closest relative. The G+C content of the genomic DNA was 30.8 mol% (HPLC). Cells were straight to curved rods, 0.5–1.0 μm in diameter and 3.0–9.0 μm in length. The temperature range for growth was 20–45 °C, with an optimum around 35 °C. Growth was not detected below 18 °C or above 47 °C. The pH range for growth was broad, pH25 °C 3.8–8.9, with an optimum at 7.0–7.5. However at pH 4.5, the strain grew at 52 % of the optimal growth rate. The salinity range was 0–1.5 % NaCl (w/v). Strain JW/YJL-B3T utilized beef extract, Casamino acids, peptone, tryptone, arabinose, cellobiose, fructose, galactose, glucose, lactose, maltose, mannose, raffinose, ribose, sucrose, xylose, pyruvate, glutamate and inulin as a carbon and energy source. There were no indications of growth under aerobic or autotrophic conditions. The isolate produced acetate, butyrate and ethanol as fermentation end products from glucose. Based on these characteristics and other physiological properties, the isolate is placed into the novel taxon, Clostridium aciditolerans sp. nov., with strain JW/YJL-B3T (=DSM 17425T=ATCC BAA-1220T) as the type strain.