代谢工程方法对木糖利用菌株的优化x

shamebagBiotechnology

Feb 22, 2013 (4 years and 10 months ago)

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申明华

制药工程

Metabolic engineering of

xylose metabolic
pathway

optimization

Bärbel

Hahn
-
Hägerdal
,

born

in

1943
,

was

appointed

professor

of

Applied

Microbiology

1990

and

is

now

emerita

professor

at

the

division

of

Applied

Microbiology
.



Her

work

initially

focused

on

the

enzymatic

hydrolysis

of

cellulose,

but

has

in

the

past

15

years

turned

to

the

fermentation

of

lignocellulosic

hydrolysates

with

recombinant

strains

of

baker’s

yeast

Saccharomyces

cerevisiae
.


Biotechnology

for

Biofuels

is

an

open

access,

peer
-
reviewed

online

journal

featuring

high
-
quality

studies

describing

technological

and

operational

advances

in

the

production

of

biofuels

from

biomass
.

Aims & scope

www.biotechnologyforbiofuels.com






PPP

Ethanol

TMB3001

stable for more than 40 generations

S. Cerevisiae
CEN.PK 113
-
7A

XR, XDH, and XK

grew on xylose only in the presence of oxygen

Anaerobic ethanol formation from xylose by recombinant
S. cerevisiae was
demonstrated
for the first time.

Strain construction

XR
XDH
XK

XR XDH
XK

TMB 3399

TMB 3400

S. Cerevisiae USM21


chromosomal integration

chemical mutagenesis

Xylitol

Xylitol

metabolic
engineering

random
mutagen
esis

Higher growth rate

Lower xylitol yield

……


XI XK PPP

ΔGRE3

TMB3045

XI XK PPP

ΔGRE3


TMB3050

repeated cultivation
on xylose medium

本文中对菌株的改造

主要通过一下几个方面:


1 GRE3
的敲除

2
下游
XKS

PPP
途径的加强


3
外源
XR
-
XDH
途径的引入

TMB3044

TMB3057

TMB3066

XR
-
XDH
,多拷
贝游离型质粒
灙p


,多拷贝游
离型质粒
奅灈塔

Aerobic growth

Anaerobic xylose


fermentation

TMB3057

TMB3066

TMB3400


Fermentation of
lignocellulose

hydrolysate

XI
路径

XR
-
XDH
路径

优势

木糖醇累积量少

乙醇得率高

木糖代谢相对较快

乙醇的生产效率高

劣势

木糖代谢缓慢

乙醇的生产效率低

氧化还原力不平衡木糖醇
累积量大

乙醇得率低

Xylose

Xylitol

Xylulose

XR

XDH

NADP
+

NADPH

NAD
+

NADH


XDH
的定向进化

NADP
+

NADPH

207A

208R

209S

211R

207D

208I

209F

211N

XDH

XDH

26

Watanabe, S.,
Kodaki
, T., and Makino, K. J. Biol. Chem., 2005,280, 10340
-
10349.





Cellulosic
biomass

XKS1

Glycolysis

Ethanol

XI

Pretreatment

Hemicellulose

Xylose

Cellulose

Pretreatment

Glucose

Pyruvate

xylose

xylulose

5P
-
xylulose

PPP

xylitol

XR

XDH

Upstream

module

Downstream

module

31