Cell-free synthetic enzymatic biosystem is emerging to expand the traditional biotechnological mode by utilizing a number of purified/partially purified enzymes and coenzymes in a single reaction vessel for the production of desired products from low-cost substrates. Here, a cell-free synthetic biosystem containing minimized number of reactions was designed for the conversion of d-glucose to l-lactate via pyruvate. This NADH-balanced biosystem was comprised of only 5 thermophilic enzymes without ATP supplementation. After optimization of enzyme loading amounts, buffer concentration and cofactor concentration, d-glucose was converted to l-lactate with a product yield of ∼90%. Our study has provided an emerging platform with potentials in producing pyruvate-derived chemicals, and may promote the development of cell-free synthetic enzymatic biosystems for biomanufacturing.
Disaccharides are valuable oligosaccharides
with an increasing
demand in the food, cosmetic, and pharmaceutical industries. Disaccharides
can be manufactured by extraction from the acid hydrolysate of plant-derived
substrates, but this method has several issues, such as the difficulty
in accessing natural substrates, laborious product separation processes,
and troublesome wastewater treatment. A chemical synthesis using glucose
was developed for producing disaccharides, but this approach suffers
from a low product yield due to the low specificity and requires tedious
protection and deprotection processes. In this study, we adopted an
artificial strategy for producing a variety of value-added disaccharides
from low-cost starch through the construction of an in vitro synthetic enzymatic platform: two enzymes worked in parallel to
convert starch to glucose and glucose 1-phosphate, and these two intermediates
were subsequently condensed together to a disaccharide by a disaccharide
phosphorylase. Several disaccharides, such as laminaribiose, cellobiose,
trehalose, and sophorose, were produced successfully from starch with
the yields of more than 80% with the help of kinetic mathematical
models to predict the optimal reaction conditions, exhibiting great
potential in an industrial scale. This study provided a promising
alternative to reform the mode of disaccharide manufacturing.
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