Characterization of a novel Clostridium sp. SP17-B1 and its application for succinic acid production from hevea wood waste hydrolysate.

An anaerobic, gram-positive, rod-shaped bacterium strain SP17-B1, isolated from dog saliva, was taxonomically characterized on the basis of phenotypic, chemotaxonomic, and genotypic characteristics. It was cultured in 4% (w/v) NaCl at a pH range of 5.0-8.0 (optimally at pH 7) and at 30°C-40 °C (optimally at 37 °C). Its major cellular fatty acids are C_16:0 (36.3%), C_17:0 cyclo (9.7%), C_16:1ω9c (13.9%), and C_18:1ω9c (10.7%), and its DNA guanine-cytosine content is 40.8 mol%. On the basis of the 16S rRNA gene sequence analysis, it was determined that the strain belonged to the genus Clostridium and was closely related to C. amygdalinum BR-10^T (97.8%), C. saccharolyticum WM1^T (97.8%), and C. celleracrescens DSM 5628^T (97.7%). This strain showed a low level of DNA-DNA relatedness with the closely related strains, suggesting that it is a novel species in the genus Clostridium. Recent studies have demonstrated the production of succinic acid using Clostridium strains. Strain SP17-B1 produced 25.1 ± 1.3 and 15.3 ± 1.5 g/L of succinic acid from 40 g/L of glucose and 30 g/L of hevea wood waste hydrolysate (HH), respectively, after 24 h. When detoxified HH was used as a substrate, the lag phase was reduced and cell growth was enhanced by 7 fold (OD₆₆₀ 0.4-3.0) within 12 h. Detoxification using granular activated carbon may have reduced the levels of furfural and HMF without interfering with the amount of sugars in HH.