11.08.2015   Advances in Biochemical Engineering/Biotechnology

Xylose

Since S. cerevisiae cannot utilize xylose, but does utilize and ferment its iso­mer D-xylulose [1,2], the obvious first step to allow xylose metabolism is to introduce a heterologous pathway converting xylose to xylulose. Over the years, several approaches have been explored to express a pentose utilization pathway from naturally pentose-utilizing bacteria and fungi in S. cerevisiae. Figure 1 summarizes the initial pathways for D-xylose utilization in bacteria and fungi.

Ul

О

Strain

Relevant

genotype/phenotype

Sugar composition

Xylose

cons.

rate

Ethanol

yield

Xylitol

yield

Ref.

to

strain

Ref. to

ferm.

data

H1693

XYLl, XYL2

50 g/1 xyl

0.09

0.04

0.47

[100]

[100]

H1691

XYL1, XYL2, XKS1

50 g/1 xyl

0.20

0.12

0.41

[100]

[100]

TMB3001

XYLl, XYL2, XKS1

50 g/1 glu + 50 g/1 xyl

0.06

0.23

0.16b

[79]

[4]

A4

XYLl, XYL2, XKS1

50 g/1 glu + 50 g/1 xyl

0.21

0.27

0.27b

[4]

[4]

A6

XYLl, XYL2, XKS1

50 g/1 glu + 50 g/1 xyl

0.14

0.27

0.32b

[4]

[4]

TMB3399

XYLl, XYL2, XKS1 introduced in USM21

20 g/1 xyl

NR

0.05

0.59

[5]

[5]

TMB3400

Xylose-growing strain isolated

after chemical mutagenesis of TMB3399

20 g/1 xyl

NR

0.18

0.25

[5]

[5]

Cl

Xylose-growing strain evolved from TMB3001

10 g/1 xyl

0.56

0.24

0.32

[131]

[131]

H2674 (control)

XYLl, XYL2, XKS1

50 g/1 xyl

0.07

0.14

0.56

[115]

[115]

H2673 (GPD1)

XYLl, XYL2, XKS1, GPD1 overexpression

50 g/1 xyl

0.06

0.17

0.49

[115]

[115]

H2723 (Azwfl)

XYLl, XYL2, XKS1, Azwfl

50 g/1 xyl

0.05

0.18

0.29

[115]

[115]

H2684 (GPDIAzwfl) XYL1, XYL2, XKS1, GPD1 overexpression, Azwfl

50 g/1 xyl

0.06

0.31

0.35

[115]

[115]

TMB3001

XYLl, XYL2, XKS1

20 g/1 glu + 50 g/1 xyl

0.39

0.33

0.48

[79]

[121]

CPB. CR1 (A gdhl)

XYLl, XYL2, XKS1, Agdhl

20 g/1 glu + 50 g/1 xyl

0.28

0.16

0.21

[121]

[121]

CPB. CR4 (Agdhl GDH2)

XYLl, XYL2, XKS1, Agdhl GDH2

20 g/1 glu + 50 g/1 xyl

0.45

0.39

0.26

[121]

[121]

CPB. CR5

(Agdhl GS-GOGAT)

XYLl, XYL2, XKS1, Agdhl GS-GOGAT

20 g/1 glu + 50 g/1 xyl

0.39

0.28

0.52

[121]

[121]

TMB3001

XYLl, XYL2, XKS1

50 g/1 glu + 50 g/1 xyl

NR

0.331

0.30

[79]

[7]

Table 1 Xylose consumption rates (gxylose/gbiomassh), ethanol yields (gethanol/gsugar), and xylitol yields (gxylitol/gxylose) in anaerobic batch cultures with glucose and xylose or only xylose by recombinant S. cerevisiae strains. Defined mineral medium was used if other medium is not indicated

В. Hahn-Hagerdal et al.

Strain

Relevant

genotype/phenotype

Sugar composition

Xylose

cons.

rate

Ethanol

yield

Xylitol

yield

Ref.

to

strain

Ref. to

ferm.

data

TMB3001

XYLl, XYL2, XKS1

20 g/1 glu + 50 g/1 xyl

0.21

0.15c

0.59d

[79]

[54]

TMB3260

XYLl, XYL2, XKS1, high XR activity

20 g/1 glu + 50 g/1 xyl

0.22

0.19c

0.48 d

[93]

[54]

TMB3062

XYLl, XYL2, XKS1, XR, and XDH on plasmid

20 g/1 glu + 50 g/1 xyl

0.14

0.29c

0.22d

[54]

[54]

TMB3056

XYLl, XYL2, XKS1, AGRE3, XR, and XDH on plasmid

20 g/1 glu + 50 g/1 xyl

0.11

0.24c

0.22d

[42]

[54]

TMB3057

XYLl, XYL2, XKS1, AGRE3, overexpressed PPP, XR, and XDH on plasmid

20 g/1 glu + 50 g/1 xyl

0.25

0.27c

0.28d

[42]

[54]

Table 1 (continued)

NR: not reported

a Batch culture by pulsing a chemostat culture b Calculated from reference c Ethanol yield on xylose d Calculated after glucose depletion

Strain

Relevant

genotype/phenotype

Conditions

Xylose

cons.

rate

Ethanol

yield

Xylitol

yield

Ref.

to

strain

Ref. to

ferm.

data

TMB3001c-p6XFP/ ТМВЗООІс expressing phosphoketolase, p4PTA/p5EHADH2 phosphotransacetylase, and acetaldehyde dehydrogenase

50 g/1 glucose + 50 g/1 xylose

0.07

0.12

0.30

[128]

[128]

TMB 3001

XYL1, XYL2, XKS1

10 g/1 xylose, 72 h

0.026

0.21

0.44

[98]

[98]

TMB 3120

XYL1, XYL2, XKS1, AGRE3

10 g/1 xylose, 72 h

0.031

0.09

0.46

[98]

[98]

TMB 3050

T. th XI, XK, AGRE3, overexpressed PPP

50 g/1 xyl

0.002

0.29

0.23

[42]

[42]

MT8-1/Xyl

XYL1, XYL2, XKS1

50 g/1 xylose + casamino acids, 72 h

NR

0.37

0.04a

[14]

[14]

Table 2 (continued)

NR: not reported a Calculated from reference

NR: not reported

a Measured and corrected by closing the DR balance b Calculated from reference

Fig.1 The initial xylose utilization pathways in bacteria and fungi

2.1