Co-expression of a β-d-xylosidase from Thermotoga maritima and a Family 10 xylanase from A. cellulolyticus significantly improves the xylan degrading activity of the Caldicellulosiruptor bescii exoproteome
[2]
- Univ. of Georgia, Athens, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chung-Ang Univ., Seoul (Korea, Republic of)
- Univ. of Georgia, Athens, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Caldicellulosiruptor species are hyperthermophilic, Gram-positive, anaerobes and the most thermophilic cellulolytic bacteria so far described. They have been engineered to convert switchgrass to ethanol without pretreatment and represent a promising platform for the production of fuels, chemicals and materials from plant biomass. Xylooligomers such as xylobiose and xylotriose that result from the breakdown of plant biomass more strongly inhibit cellulase activity than do glucose or cellobiose. High concentrations of xylobiose and xylotriose, are present in C. bescii fermentations after 90 h incubation and removal or breakdown of these types of xylooligomers is crucial to achieve high conversion of plant biomass to product. In previous studies the addition of exogenous β-d-xylosidase substantially improved the performance of glucanases and xylanases in vitro. β-d-Xylosidases are, in fact, essential enzymes in commercial preparations for efficient deconstruction of plant biomass. In addition, the combination of xylanase and β-d-xylosidase is known to exhibit synergistic action on xylan degradation. In spite of its ability to grow efficiently on xylan substrates, no extracellular β-d-xylosidase was identified in the C. bescii genome. Here we report that the co-expression of a thermal stable β-d-xylosidase from Thermotoga maritima and a xylanase from Acidothermus cellulolyticus in a C. bescii strain containing the A. cellulolyticus E1 endoglucanase significantly increased the activity of the exoproteome as well as growth on xylan substrates. The combination of these enzymes also resulted in increased growth on crystalline cellulose in the presence of exogeneous xylan.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1785339
- Report Number(s):
- NREL/JA-2A00-80128; MainId:42331; UUID:cc9bfef5-c18c-4365-a62d-0fe42f32924e; MainAdminID:24534
- Journal Information:
- Applied and Environmental Microbiology, Vol. 87, Issue 14; ISSN 0099-2240
- Publisher:
- American Society for MicrobiologyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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