Maltotriosyl-erythritol, a transglycosylation product of erythritol by Thermus sp. amylomaltase and its application to prebiotic

In this study, maltotriosyl-erythritol (EG3) was synthesized as a novel prebiotic candidate via transglycosylation using recombinant amylomaltase (AMase) from Thermus sp. Tapioca starch served as the glucosyl donor, and erythritol as the acceptor. High-performance liquid chromatography (HPLC) revealed an EG3 yield of 14.0 % with a concentration of 2.8 mg/mL. Mass spectrometry confirmed the molecular weight of EG3 as 608 Da, and its strucopture was verified by 1H and 13C NMR analysis. EG3 exhibited greater resistance to acid, heat, and digestive enzymes compared to erythritol glucosides (EG1-2) and significantly promoted the growth of Lactobacillus casei BCC36987. Fermentation of EG3 resulted in the highest levels of lactic acid and total short-chain fatty acids, which may contribute to reduced pH levels. These findings suggest that erythritol-receptor products formed via AMase-catalyzed reactions, particularly EG3, are promising prebiotic ingredients, with the prebiotic activity of erythritol derivatives being influenced by the length of the carbohydrate chain.

Enzymatic Synthesis of Maltitol and Its Inhibitory Effect on the Growth of Streptococcus mutans DMST 18777

This study aimed to synthesize maltitol using recombinant CGTase from Bacillus circulans A11 with β-cyclodextrin (β-CD) and sorbitol as a glucosyl donor and acceptor, respectively, and assess its antibacterial activity. Optimal conditions for producing the highest yield, 25.0% (w/w), were incubation of 1% (w/v) β-CD and sorbitol with 400 U/mL of CGTase in 20 mM phosphate buffer at pH 6.0 and 50 °C for 72 h. Subsequently, maltitol underwent large-scale production and was purified by HPLC. By mass spectrometry, the molecular weight of the synthesized maltitol was 379.08 daltons, corresponding exactly to that of standard maltitol. The relative sweetness of synthesized and standard maltitol was ~90% of that of sucrose. Spot assay on the agar plate showed that maltitol inhibited the growth of Streptococcus mutans DMST 18777 cells. In addition, the MIC and MBC values of synthesized and standard maltitol against S. mutans were also determined as 20 and 40 mg/mL, respectively. These results show that the synthesized maltitol can be produced at high yields and has the potential to be used as an anticariogenic agent in products such as toothpaste.

Heterologous expression of 4α-glucanotransferase: overproduction and properties for industrial applications

4α-Glucanotransferase (4α-GTase) is unique in its ability to form cyclic oligosaccharides, some of which are of industrial importance. Generally, low amount of enzymes is produced by or isolated from their natural sources: animals, plants, and microorganisms. Heterologous expressions of these enzymes, in an attempt to increase their production for applicable uses, have been widely studied since 1980s; however, the expressions are mostly performed in the prokaryotic bacteria, mostly Escherichia coli. Site-directed mutagenesis has added more value to these expressed enzymes to display the desired properties beneficial for their applications. The search for further suitable properties for food application leads to an extended research in expression by another group of host organism, the generally-recognized as safe host including the Bacillus and the eukaryotic yeast systems. Herein, our review focuses on two types of 4α-GTase: the cyclodextrin glycosyltransferase and amylomaltase. The updated studies on the general structure and properties of the two enzymes with emphasis on heterologous expression, mutagenesis for property improvement, and their industrial applications are provided.