ABSTRACT
In this study, we constructed a yeast consortium surface-display expression system by using Flo1 as an anchor protein. Endoglucanase II (EGII) and cellobiohydrolase II (CBHII) from Trichoderma reesei, and β3-glucosidase 1 (BGLI) from Aspergillus aculeatus were immobilized on Saccharomyces cerevisiae Y5. We constructed the cellulose-displaying expression yeast consortium (Y5/fEGII:Y5/fCBHII:Y5/fBGLI = 1:1:1) and investigated the enzymatic ability and ethanol fermentation. The displayed cellulolytic enzymes was stabile during the 96-h fermentation. The yeast consortium produced 0.77 g/L ethanol from 10 g/L phosphoric acid swollen cellulose (PASC) within 96 h. The yield (in grams of ethanol produced per gram of carbohydrate consumed) was 0.35 g/g, which correspond to 68.6% of the theoretical yield.
Subject(s)
Aspergillus , Cellulase , Genetics , Cellulose , Metabolism , Cellulose 1,4-beta-Cellobiosidase , Genetics , Enzymes, Immobilized , Genetics , Ethanol , Metabolism , Fermentation , Glucosidases , Genetics , Mannose-Binding Lectins , Metabolism , Protein Binding , Saccharomyces cerevisiae , Genetics , Metabolism , Saccharomyces cerevisiae Proteins , Metabolism , TrichodermaABSTRACT
Saccharomyces cerevisiae is useful as a host for genetic engineering, since it allows the folding and glycosylation of expressed heterologous eukaryotic proteins and can be subjected to many genetic manipulations. Recent advancements in the yeast cell surface engineering developed strategies to genetically immobilize amylolytic, cellulolytic and xylanolytic enzymes on yeast cell surface for the production of fuel ethanol from biomass. We reviewed the basic principle and progress of S. cerevisiae cell-surface engineering and gave an insight into the recent technological developments in the production of bioethanol using surface engineered yeast.
Subject(s)
Biofuels , Microbiology , Ethanol , Metabolism , Fermentation , Metabolic Engineering , Methods , Recombinant Proteins , Genetics , Saccharomyces cerevisiae , Genetics , MetabolismABSTRACT
A library with potential to produce six amino acids cyclic peptides was prepared using pET-28a as the starting plasmid. pVmut was used to amplify the Int(C)-dnaB-N-Int(N) fragment that was inserted into pET28a to give pEV. On pEV, DnaB split intein was expressed under the strong T7 promoter. Analyses of Escherichia coli transformed with pEV showed that DnaB split intein was produced in large quantity and the fusion protein self-spliced efficiently to produce cyclized DnaB-N. A synthesized 115 bp fragment mixture encoding 5 random amino acids was inserted into pEV to generate pEV-IS. The ligation mixture was transformed into E. coli. A library of 10(3) clones was obtained, 20 randomly picked clones were sequenced. All of them contain different sequences. Nine clones were chosen for further analysis. Split-intein-ISs were expressed in large quantity, and 90% of them self-spliced under 16 degrees C in 20 hours. After induction at 30 degrees C for 3 hours, the expressed DnaB split intein was purified using His-column, and then a molecular weight of target cyclic peptide was detected by MALDI-TOF-MS.
Subject(s)
Humans , Amino Acids , Chemistry , Base Sequence , DnaB Helicases , Chemistry , Genetics , Escherichia coli , Genetics , Metabolism , Genetic Vectors , Genetics , Inteins , Genetics , Molecular Sequence Data , Peptide Library , Peptides, Cyclic , Chemistry , Protein Splicing , Recombinant Fusion Proteins , Genetics , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Synechocystis , ChemistryABSTRACT
Electricigens play an important role in microbial fuel cell(MFC) . This review provides an introduction of different electricigens on theirs taxonomical group,biochemical,physiological and morphological characteristics. The ability of electricity production of electricigens and electron transfer mechanisms in microbial fuel cells are also concluded. The prospect of waste water treatment and bio-electricity production is underlined,it is point out in this review that the future research of microorganism for MFC should be focused on enrichment,adaptation,modification and optimization by multi-strains application to improve the performances of MFC.