Synthesis of a Healthy Sweetener d-Tagatose from Starch Catalyzed by Semiartificial Cell Factories

Abstract

d-Tagatose is one of the several healthy sweeteners that can be a substitute for sucrose and fructose in our daily life. Whole cell-catalyzed phosphorylation and dephosphorylation previously reported by our group afford a thermodynamic-driven strategy to achieve tagatose production directly from starch with high product yields. Nonetheless, the poor structural stability of cells and difficulty in biocatalyst recycling restrict its practical application. Herein, an efficient and stable semiartificial cell factory (SACF) was developed by constructing an organosilica network (OSN) artificial shell on the cells bearing five thermophilic enzymes to produce tagatose. The OSN artificial shell, the thickness of which can be regulated by changing the tetraethyl silicate concentration, exhibited tunable permeability and superior mechanical strength. In contrast with cells, SACFs showed a relative activity of 99.5% and an extended half-life from 33.3 to 57.8 h. Over 50% of initial activity was retained after 20 reuses. The SACFs can catalyze seven consecutive reactions with tagatose yields of over 40.7% in field applications.

Advances and Prospects of d-Tagatose Production Based on a Biocatalytic Isomerization Pathway

“…Ultimately, it produced 0.8 M D-tagatose from 1 M D-fructose in 16 h with a conversion rate as high as 80%. To further reduce costs, Han et al [36] successfully realized the production of D-tagatose using cheap starch as a substrate. This pathway of multienzyme-catalyzed reaction contains α-glucan phosphorylase, phosphoglucomutase, phosphoglucose isomerase, tagatose 6-phosphate 4-epimerase, and tagatose 6-phosphate phosphatase.…”

Characterization of a Metallic-Ions-Independent L-Arabinose Isomerase from Endophytic Bacillus amyloliquefaciens for Production of D-Tagatose as a Functional Sweetener

“…D-Tagatose is a rare monosaccharide that recently occupies a significant niche among emerging low-calorie sweeteners. It has been considered a potential replacement for sucrose due to its low calorific value and resemblance to sucrose taste, with no cooling effect, aftertaste, or potentiation of off-flavors [1][2][3][4]. D-Tagatose has a relative sweetness value of 92% when compared with sucrose, with a low glycemic effect [1].…”