Production Of 2,3-butanediol From Xylose By Recombinant Serratia Marcescens MG1

2,3-butanediol is an important bio-based products,it has more applications in the fields of chemicals,energy,food and agriculture.Currently,the biological synthesis of 2,3-butanediol has reached a higher level,to reduce production costs become an important issue.Xylose is the second most abundant sugar in lignocellulosic hydrolyzate,that is wide variety sources.Screening or build a recombinant strain is research focus,that can fermenttation lignocellulosic hydrolysis or other raw materials.Serratia marcescens is 2,3-butanediol potential industrial production strain,but the capacity of xylose metabolic is low,construction engineered strain is necessary.This paper focuses on Serratia marcescens MG1 xylose fermentation production of 2,3-butanediol,in substrate utilization and xylose fermentation conditions to carry out research,the main results are as follows:1.Xylose isomerase gene of Serratia marcescens was cloned.Medium components is xylose 40g/L,yeast extract 5g/L,NH4H2PO43g/L,sodium citrate 14g/L,sodium acetate 4g/L,MgSO40.5g/L,MnSO40.05g/L.Optimal culture conditions is 5%inoculation,the temperature is 30?,pH 6.0.Under the conditions,Serratia marcescens MG1 can use 20g/l of xylose to produce 2,3-butanediol.2.The construction of plasmid pUC18-pbudR-xylA-Amp electroporation Serratia marcescens MG1 expression,the promoter is MG1 acetoin operon promoter,constructed of engineering strain soluble exogenous xylose isomerase gene expression and the high expression of xylose utilization increased to 30.5 g/L,recombinant Serratia marcescens xylose metabolism yield 2,3-butanediol/was 8.5g/1,a 55%increase.3.Co-fermentation of xylose and glucose metabolism has been further improved xylose utilization,for studying the two sugar concentration ratio,optimize pH,concentration ofxylose,glucose concentration,using a central composite response surface analysis methods.Best of fermentation conditions is pH6.3,xylose concentration 55g/L,glucose concentration 16.5g/L.In this condition,engineered Serratia marcescens MG1 in shake flasks,2,3-butanediol results for conversion is 0.29g/g,production is 20.1g/L,the productivity is 6.7g/L/t.