TABLE 2.

Bio-production of D-allulose by engineered strains.

	Enzyme and	Base	Host	Expression cassette	Activities, yields, and
Origin of gene	molecular weight	numbers	strains	and expression	publishing years
P. cichorii ST-24	DTEase, 32.5 kDa	873 bp	E. coli XLl-Blue	pBluescript II-SK-DTE soluble expression	0.35 U/mL (Ishida et al., 1997a), 1997
C. scindens ATCC 35704	DTEase, 31 kDa	864 bp	E. coli BL21	pET-22b (+)-DTE soluble expression	27. 9% (Xing et al., 2011), 2011
C. cellulolyticum H10 ATCC35319	DAEase, 32 kDa	882 bp	E. coli BL21	pET-22b(+)-Cc-dpe, soluble expression	218 g/L (Mu et al., 2011), 2011
Ruminococcus sp. 5_1_39BFAA	DAEase, 33 kDa	876 bp	E. coli BL21	pET-21a-dpe, soluble expression	8.95 U/mg, 125 g/L (Zhu et al., 2012), 2012
Clostridium sp. BNL1100	DAEase, 32 kDa	879 bp	E. coli BL21	pET-22b(+)-Clsp-dpe, soluble expression	120 g/L (Mu et al., 2013), 2013
A. tumefaciens str. C58	DAEase, 33 kDa	870 bp	E. coli BL21	pET22b (+)/pelb-dpe, secretion	10.9 U/mL, 179 g/L (Gu et al., 2013), 2013
E. coli JM109	DTEase, 29.8 kDa	789 bp	E. coli BL21	pET-15b-DTE, soluble expression	No data (He et al., 2015), 2015
A. tumefaciens	DAEase, 33 kDa	870 bp	S. cerevisiae AN120	pRS424-TEFpr-ss-xy/A soluble expression	12.0% (Li et al., 2015), 2015
A. tumefaciens ATCC 33970	DAEase, 33 kDa	870 bp	E. coli ER2566	pET-24a(+)-dpe, soluble expression	230 g/L (Park et al., 2016b), 2016
Treponema primitia ZAS-1	DAEase, 33.3 kDa	888 bp	E. coli BL21	pET-22b(+)-dpe, secretion	137.5 g/L (Zhang et al., 2016b), 2016
Ruminococcus sp. 5_1_39BFAA	DAEase, 33 kDa	876 bp	B. subtilis 1A751	pMA5-Pxy/A-RDPE, secretion	95 U/mL, 145 g/L (Chen et al., 2016), 2016
Ruminococcus sp. 5_1_39BFAA	DAEase, 33 kDa	876 bp	B. subtilis	pNCMO2-P2-dpe, soluble expression	58.6 U/mg (Li et al., 2018a), 2018
A. tumefaciens	DAEase, 33 kDa	870 bp	K. marxianus	pRS42H-dpe, soluble expression	190 g L–1 (Yang et al., 2018), 2018