Microbial transglutaminase (MTG) is an enzyme widely used in the food industry. Mutiple-site mutagenesis of Streptomyces mobaraensis transglutaminase was performed in Escherichia coli. According to enzymatic assay and thermostability study, among three penta-site MTG mutants (DM01-03), DM01 exhibited the highest enzymatic activity of 55.7 ± 1.4 U/mg and longest half-life at 50 °C (418.2 min) and 60 °C (24.8 min).

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Rare sugar D-allulose as a substitute sweetener is produced through the isomerization of D-fructose by D-tagatose 3-epimerases (DTEases) or D-allulose 3-epimerases (DAEases). D-Allulose is a kind of low energy monosaccharide sugar naturally existing in some fruits in very small quantities. D-Allulose not only possesses high value as a food ingredient and dietary supplement, but also exhibits a variety of physiological functions serving as improving insulin resistance, antioxidant enhancement, and hypoglycemic controls, and so forth. Thus, D-allulose has an important development value as an alternative to high-energy sugars. This review provided a systematic analysis of D-allulose characters, application, enzymatic characteristics and molecular modification, engineered strain construction, and processing technologies. The existing problems and its proposed solutions for D-allulose production are also discussed. More importantly, a green and recycling process technology for D-allulose production is proposed for low waste formation, low energy consumption, and high sugar yield.

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D-Allulose as a low-energy and special bioactive monosaccharide sugar is essential for human health. In this study, the D-psicose-3-epimerase gene (DPEase) of Agrobacterium tumefaciens was transferred into thermotolerant Kluyveromyces marxianus to decrease the production cost of D-allulose and reduce the number of manufacturing procedures. The cell regeneration of K. marxianus and cyclic catalysis via whole-cell reaction were investigated to achieve the sustainable application of K. marxianus and the consumption of residual D-fructose. Results showed that DPEase, encoding a 33 kDa protein, could be effectively expressed in thermotolerant K. marxianus. The engineered K. marxianus produced 190 g L D-allulose with 750 g L D-fructose as a substrate at 55 °C within 12 h. Approximately 100 g of residual D-fructose was converted into 34 g of ethanol, and 15 g of the engineered K. marxianus cells was regenerated after fermentation at 37 °C for 21 h. The purity of D-allulose of more than 90% could be obtained without isolating it from D-allulose and D-fructose mixture through residual D-fructose consumption. This study provided a valuable pathway to regenerate engineered K. marxianus cells and achieve cyclic catalysis for D-allulose production.

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A two‐dimensional BiOI/MoS2 heterojunction is fabricated by in situ growth of MoS2 on BiOI nanosheets through a hydrothermal method and then as a carrier for loading on Pt nanoparticles. Transmission electron microscopy shows that Pt nanoparticles are decorated uniformly on the surface of BiOI/MoS2 nanosheets. The obtained Pt‐BiOI/MoS2 is utilized as an electrocatalyst for the methanol oxidation reaction in alkaline conditions under visible light irradiation. Electrochemical evaluations indicate that as‐prepared Pt‐BiOI/MoS2 expresses the highest methanol oxidation reaction activity and stability, and the maximum current density reaches 1007.2 mA mg−1Pt under visible light irradiation, which is 12 and 3.5 times higher compared with Pt‐BiOI and commercial Pt/C electrodes, respectively, in the traditional electrocatalytic process. The results suggest that a synergy of photo‐ and electro‐processes improves the photoelectrocatalytic performance of Pt‐BiOI/MoS2 in the methanol oxidation reaction.