Characterization of a thermostable xylanase from a newly isolated Kluyvera species and its application for biobutanol production

Kluyvera species strain OM3 isolated from spent mushroom substrate could produce a high level of cellulase-free xylanase (5.12. U/mL). This xylanase showed maximum activities at 70. °C and pH 8.0, which could retain 100% and 71% activity after 1. h incubation at 60. °C and 70. °C, and maintain stability over a wide range of pHs (5.0-9.0), indicating its thermal and pH stability. Moreover, the xylanase could hydrolyze untreated lignocellulosics (e.g., palm oil fiber) to reducing sugars with a yield of 27.1-46.9. mg/g. A co-culture consisting of Kluyvera sp. strain OM3 and Clostridium sp. strain BOH3 could directly convert birchwood xylan to 1.2. g/L butanol, which was comparable to the amount of butanol (1.7. g/L) generated via separate hydrolysis by the xylanase and fermentation by Clostridium sp. strain BOH3. This is the first report on the production, characterization of a xylanase from genus Kluyvera and its application for butanol production directly from hemicelluloses.