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PLoS One. 2013 Jul 30;8(7):e70631. doi: 10.1371/journal.pone.0070631. Print 2013.

Metabolic adaption of ethanol-tolerant Clostridium thermocellum.

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  • 1Shandong Provincial Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China.

Abstract

Clostridium thermocellum is a major candidate for bioethanol production via consolidated bioprocessing. However, the low ethanol tolerance of the organism dramatically impedes its usage in industry. To explore the mechanism of ethanol tolerance in this microorganism, systematic metabolomics was adopted to analyse the metabolic phenotypes of a C. thermocellum wild-type (WT) strain and an ethanol-tolerant strain cultivated without (ET0) or with (ET3) 3% (v/v) exogenous ethanol. Metabolomics analysis elucidated that the levels of numerous metabolites in different pathways were changed for the metabolic adaption of ethanol-tolerant C. thermocellum. The most interesting phenomenon was that cellodextrin was significantly more accumulated in the ethanol-tolerant strain compared with the WT strain, although cellobiose was completely consumed in both the ethanol-tolerant and wild-type strains. These results suggest that the cellodextrin synthesis was active, which might be a potential mechanism for stress resistance. Moreover, the overflow of many intermediate metabolites, which indicates the metabolic imbalance, in the ET0 cultivation was more significant than in the WT and ET3 cultivations. This indicates that the metabolic balance of the ethanol-tolerant strain was adapted better to the condition of ethanol stress. This study provides additional insight into the mechanism of ethanol tolerance and is valuable for further metabolic engineering aimed at higher bioethanol production.

PMID:
23936233
[PubMed - indexed for MEDLINE]
PMCID:
PMC3728321
Free PMC Article

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