Search

• First experimental verification for synthesizing crystalline cellulose nanoribbon from inexpensive starch in one pot by two phosphorylases. • Degree of polymerization of insoluble synthetic CCNR was affected by the primer concentration based on the fixed concentration of maltodextrin. • CCNR can be used as a Pickering emulsions stabilizer and showed excellent emulsifiability. Nanocellulose has many promising applications such as a green ingredient for Pickering emulsion. Traditional strategies to produce nanocellulose, which are acid or enzymatic hydrolysis and mechanical methods on natural complicated cellulose, are hard to control and can result in significant pollutants during the processes. Herein, we demonstrated a facile and sustainable method for the biocatalytic production of insoluble synthetic crystalline cellulose nanoribbon (CCNR) from cheap maltodextrin by coupling α-glucan phosphorylase (αGP) and cellodextrin phosphorylase (CDP) using cellobiose as a primer. And by optimizing the combination of different αGP and CDP, it turned out that the optimal enzyme combination is αGP from Thermotoga maritime and CDP from Clostridium thermocellum , in which CDP was attached to a family 9 cellulose-binding module. The product yield and degree of polymerization (DP) of insoluble synthetic CCNR was affected by the primer concentration at a fixed concentration of maltodextrin. After optimization of reaction conditions, the highest product yield of insoluble synthetic CCNR was 44.92 % and the highest DP of the insoluble synthetic CCNR was 24 from 50 g 1−1 maltodextrin. This insoluble synthetic CCNR can be used as a Pickering emulsions stabilizer, showing excellent emulsifiability. This study provides a promising alternative for cost-efficient production of insoluble synthetic CCNR which was used as a green emulsion stabilizer. [ABSTRACT FROM AUTHOR]

β-Nicotinamide mononucleotide (NMN) is an important precursor in the synthesis of nicotinamide adenine dinucleotide (NAD+) and confers multiple health benefits, resulting in the rapid growth of NMN market capacity in the fields of food and health care. To overcome the drawbacks of NMN production by the existing chemical or microbial fermentation method, there is an urgent need to develop a prospective NMN production strategy with low cost, low pollution, and high yield. In this study, we demonstrated an artificial in vitro multi-enzyme cascade biocatalysis using starch and nicotinamide (Nam) as substrates for the synthesis of NMN in one-pot. This multi-enzyme cascade reaction was optimized in terms of pH value, buffer concentration, inorganic phosphate concentration, enzyme composition, and phosphoenolpyruvate concentration. Under optimized conditions, a high molar yield of 87.8% for NMN was achieved using 3.2 mM Nam as substrate, and a molar yield of 55.37% for NMN was also achieved under the initial Nam concentration of 9.21 mM. This in vitro enzymatic platform provides an environmental friendliness biomanufacturing technology for the production of NMN, showing a highly promising alternative approach for NMN production. • We created an innovative platform for the biomanufacturing of NMN from starch and Nam via in vitro multi-enzyme cascade biosystem. • This NMN production method is environmentally friendly. • The system can efficiently convert maltodextrin and Nam to NMN. [ABSTRACT FROM AUTHOR]

• SCCO obtained by bioprocessing was used as a Pickering emulsion stabilizer. • The Pickering emulsions were stable in pH ranges of 2–12 and ionic strength from 0 to 2 M. • The Pickering emulsions showed good tolerance to temperature changes from 2 to 60 °C. • The Pickering emulsions remain stable for no less than 6 months. Nanocellulose are promising Pickering emulsion stabilizers for being sustainable and non-toxic. In this work, semicrystalline cellulose oligomers (SCCO), which were synthesized from maltodextrin using cellobiose as primer by in vitro enzymatic biosystem, were exploited as stabilizers for oil-in-water Pickering emulsions. At first, the morphology, structure, thermal and rheological properties of SCCO suspensions were characterized, showing that SCCO had a sheet morphology and typical cellulose-Ⅱ structure with 56 % crystallinity. Then the kinetic stabilities of emulsions containing various amounts of SCCO were evaluated against external stress such as pH, ionic strength, and temperature. Noting that SCCO-Pickering emulsions exhibited excellent stabilities against changes in centrifugation, pH, ionic strengths, and temperatures, and it was also kinetically stable for up to 6 months. Both SCCO suspensions and their emulsions exhibited gel-like structures and shear-thinning behaviors. These results demonstrated great potential of SCCO to be applied as nanocellulosic emulsifiers in food, cosmetic and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Background: Haloacid dehalogenase (HAD)-like hydrolases represent the largest superfamily of phosphatases, which release inorganic phosphate from phosphate containing compounds, such as sugar phosphates. The HAD-like phosphatases with highly substrate specificity, which perform irreversible dephosphorylation, are always integrated into in vitro synthetic enzymatic biosystems as the last enzymatic step for the cost-efficient production of biochemicals. Therefore, identification and characterization of substrate specificity of HAD-like phosphatases are important for exploring their application. Results: In this study, a hyperthermophilic HAD-like phosphatase from Archaeoglobus fulgidus (AfPase) was cloned, expressed, and characterized. AfPase was identified as a type I Mg2+-dependent HAD-like phosphatase with high optimal temperature and thermostability. Among the tested phosphate containing compounds, AfPase exhibited the highest catalytic activity on p-nitrophenyl phosphate, followed by dihydroxyacetone phosphate (DHAP). On the basis of the high catalytic activity of AfPase to generate 1,3-dihydroxyacetone (DHA) from DHAP, an in vitro synthetic enzymatic biosystem containing this phosphatase and other five enzymes was constructed for the biosynthesis of DHA from inexpensive maltodextrin in one pot. About 14 mM (1.26 g/L) DHA was produced from 10 g/L maltodextrin. Conclusions: A hyperthermophilic HAD-like phosphatase from Archaeoglobus fulgidus was characterized carefully, and the success of an in vitro synthetic enzymatic biosystem containing this phosphatase provided a promising approach for DHA production from maltodextrin. [ABSTRACT FROM AUTHOR]