Enhanced expression of the codon-optimized exo-inulinase gene from the yeast Meyerozyma guilliermondii in Saccharomyces sp. W0 and bioethanol production from inulin

Abstract

In the present study, after the exo-inulinase gene INU1 from Meyerozyma guilliermondii was optimized according to the codon usage bias of Saccharomyces cerevisiae, both the optimized gene INU1Y and the native gene INU1 were ligated into the homologous integration expression vector pMIRSC11 and expressed in Saccharomyces sp. W0. It was determined that the inulinase activity of the recombinant yeast Y13 with the optimized gene INU1Y was 43.84 U/mL, which was obviously higher than that (31.39 U/mL) produced by the recombinant yeast EX3 with the native gene INU1. Moreover, it was indicated that the recombinant yeast Y13 could produce 126.30 mg/mL ethanol from 300.0 g/L inulin while the recombinant yeast EX3 and Saccharomyces sp. W0 produced 122.75 mg/mL and 114.15 mg/mL ethanol, respectively, under the same conditions. In addition, the ethanol productivity of the recombinant yeast Y13 was 2.25 mg/mL/h within 48 h of the fermentation, which was obviously higher than that of the recombinant yeast EX3 (1.97 mg/mL/h) and Saccharomyces sp. W0 (1.77 mg/mL/h) within the same period. The results demonstrated that the recombinant yeast Y13 had higher ethanol production and productivity than the recombinant yeast EX3 and Saccharomyces sp. W0. Therefore, it was concluded that the codon optimization of the exo-inulinase gene from M. guilliermondii effectively enhanced inulinase activity and improved ethanol production from inulin by Saccharomyces sp. W0 carrying the optimized inulinase gene.

Continuous generation of fructose from Taraxacum officinale tap root extract and inulin by immobilized inulinase in a packed-bed reactor

“…Inulin rich plant materials present a great opportunity for exploitation and generation of value-added products such as bio-ethanol, single cell protein, citric acid, FOS and high fructose syrup. Inulinase obtained from microbial sources showed promising application in obtaining high-fructose syrup from plant inulin (Chi et al, 2011;Liu et al, 2014). Dandelion (Taraxacum officinale) is a perennial herb of the family Asteraceae and native to temperate areas containing ample amounts of inulin (12-15%) and oligofructans in its tap roots and leaves with ethno-pharmacological relevance and is regarded to cure antitumour, anti-diabetic, anti-rheumatic, anti-inflammatory and anti-cardiogenic disorders.…”

Efficient ethanol production from inulin by two-stage aerate strategy

“…Production of ethanol from starch-based materials is not suitable for China with large population and insufficient grain, consequently, fuel ethanol from non-grain materials is going to be the solutions to energy problems considering the increasing prices of grain and other concerns on food security, or land-use [3,4]. Inulin is a linear biopolymer made up of fructose residues linked by b-2,1 bonds [5], which can be hydrolyzed into fructooligosaccharide or single-fructose by acid, or inulinase and be further transformed into other products [6]. Inulin, as the main reserve carbohydrate, can be stored in the roots and tubers of some plants, such as Jerusalem artichoke, chicory, dahlia, and yacon [5,6].…”

“…Inulinase activity, the most important factor for the process of CBP, can be influenced by aeration rates and biomass concentration at the same time [15,16]. Unfortunately, it was paid little concerned during the ethanol fermentation [6,13,17,18].…”

“…Inulin is a linear biopolymer made up of fructose residues linked by b-2,1 bonds [5], which can be hydrolyzed into fructooligosaccharide or single-fructose by acid, or inulinase and be further transformed into other products [6]. Inulin, as the main reserve carbohydrate, can be stored in the roots and tubers of some plants, such as Jerusalem artichoke, chicory, dahlia, and yacon [5,6]. All these inulincontaining materials, especially, Jerusalem artichoke, have great potential for biofuels production because of the advantages of high yield, resistance to poor soil, drought, cold temperature and pests [7].…”

“…Consolidated bioprocessing (CBP) technology combined inulinase production, inulin hydrolysis and ethanol production, which had very outstanding advantages in the process of ethanol production [6,8]. Recently, more works focused on strains screening with inulinase activity, optimization of the fermentation conditions and modified the strains by over expression the inulinase gene (INU1) to improve the ethanol production from inulin-containing materials by CBP technology [9e14].…”