Energy Utilization Of Main Components Of Jerusalem Artichoke Based On Multi Enzyme Coordination

The aim of this paper is to construct inulinase gene,pectinase gene and xylanase gene,and make full use of the main components of Jerusalem artichoke.At first,inulinase gene was integrated into the expression vectors of galactose(GAL)inducible promoter and phosphoglycerate kinase(PGK)constitutive promoter constructed in the early stage of the laboratory to promote the utilization of inulin by Saccharomyces cerevisiae,and the ethanol yield of yeast was improved by optimizing the culture medium,and the dominant promoter PGK was screened out.In order to solve the problem that pectin and xylan in Jerusalem artichoke can not be directly used by Saccharomyces cerevisiae,pectinase gene and xylanase gene were integrated into the expression vector containing PGK promoter to promote the utilization of substrate by yeast.Secondly,inulinase gene,xylanase gene and pectinase gene were introduced into Pichia pastoris by electrical transformation,and ethanol concentration was measured after fermentation.Under the action of these three different genes,various polysaccharides in Jerusalem artichoke are hydrolyzed and converted into fermentable monosaccharides to prepare fuel ethanol,and these yeasts have important value in the preparation and application of fuel ethanol.The main results of this study are as follows:(1)Saccharomyces cerevisiae host,in the medium with inulin as substrate,the ethanol production concentration of wild-type Saccharomyces cerevisiae is 2.7 g/L,that of transgenic yeast containing PGK promoter is 71.74 g/L,and that of transgenic yeast containing GAL promoter is 60.35 g/L;In the medium with xylan as substrate,the ethanol production concentration of wild-type Saccharomyces cerevisiae was 0.909 g/L,and that of transgenic yeast containing PGK promoter was 11.17 g/L;In the medium with pectin as substrate,the ethanol production concentration of wild-type Saccharomyces cerevisiae was 2.034 g/L,and that of transgenic yeast containing PGK promoter was 11.924 g/L.(2)Pichia pastoris host,the inulinase activity was 500 U/mL,and the ethanol concentration in the medium with inulin as substrate was 9.559 g/L;Xylanase activity was 880 U/mL,and ethanol concentration in the medium with xylan as substrate was 0.7465 g/L;The pectinase activity was 700 U/mL,and the ethanol concentration in the medium with pectin as substrate was 1.3765 g/L.Saccharomyces cerevisiae as the expression of host system,relative to the wild type strain,with inulin,xylan and pectin as the substrate of transgenic strains to produce ethanol,respectively,to improve efficiency of 26 times,14 times,5 times.In the expression system of pichia pastoris as the host,transgenic strains can produce ethanol in small amounts compared with wild strains.