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Indexed by:期刊论文
Date of Publication:2013-07-01
Journal:BIOTECHNOLOGY AND BIOPROCESS ENGINEERING
Included Journals:SCIE、EI、Scopus
Volume:18
Issue:4
Page Number:721-727
ISSN No.:1226-8372
Key Words:Jerusalem artichoke tubers; Kluyveromyces marxianus; inulinase; consolidated bioprocessing (CBP); ethanol fermentation
Abstract:Ethanol production from Jerusalem artichoke tubers through a consolidated bioprocessing (CBP) strategy using the inulinase-producing yeast Kluyveromyces marxianus is an economical and competitive than that from a grainbased feedstock. However, poor inulinase production under ethanol fermentation conditions significantly prolongs the fermentation time and compromises ethanol productivity. Improvement of inulinase activity appears to be promising for increasing ethanol production from Jerusalem artichoke tubers by CBP. In the present study, expression of the inulinase gene INU with its own promoter in K. marxianus (K/INU2) was explored using the integrative cassette. Overexpression of INU was explored using chromosome integration via the HO locus of the yeast. Inulinase activity and ethanol were determined from inulin and Jerusalem artichoke tubers under fed-batch operation. Inulinase activity was 114.9 U/mL under aerobic conditions for K/INU2, compared with 52.3 U/mL produced by the wild type strain. Importantly, inulinase production was enhanced in K/INU2 under ethanol fermentation conditions. When using 230 g/L inulin and 220 g/L Jerusalem artichoke tubers as substrates, inulinase activities of 3.7 and 6.8 U/mL, respectively, were measured using K/INU2, comparing favorably with 2.4 and 3.1 U/mL, respectively, using the wide type strain. Ethanol concentration and productivity for inulin were improved by the recombinant yeast to 96.2 g/L and 1.34 g/L/h, respectively, vs 93.7 g/L and 1.12 g/L/h, respectively, by the wild type strain. Ethanol concentration and productivity improvements for Jerusalem artichoke tubers were 69 g/L and 1.44 g/L/h, respectively, from the recombinant strain vs 62 g/L and 1.29 g/L/h, respectively, from the wild type strain.
