A Novel Trehalose Synthase for the Production of Trehalose and Trehalulose

Engineering a high-sugar tolerant strain of Saccharomyces cerevisiae for efficient trehalose production using a cell surface display approach

Trehalose production via a one-step enzymatic route using trehalose synthase (TreS) holds significant promise for industrial-scale applications due to its simplicity and utilization of low-cost substrates. However, the development of a robust whole-cell biocatalyst expressing TreS remains crucial for enabling practical and economically viable production. In this study, a high-sugar tolerant strain of S. cerevisiae was screened and employed as a host cell for the cell surface display of TreS from Acidiplasma aeolicum. The resultant strain, S. cerevisiae I3A, exhibited remarkable surface displayed TreS activity of 3358 U/g CDW and achieved approximately 64% trehalose yield (10.8 g/L/h productivity) from maltose. Interestingly, no glucose by-product was observed during trehalose production. The S. cerevisiae I3A cells exhibited reusability for up to 12 cycles leading to potential cost reduction of trehalose products. Therefore, our study demonstrated the development of a high-sugar tolerant S. cerevisiae strain expressing TreS on its surface as a whole-cell biocatalyst for efficient and economical trehalose production with potential applications in the food and pharmaceutical industries.

Trehalulose: Exploring its benefits, biosynthesis, and enhanced production techniques

The increasing concern over sugar-related health issues has sparked research interest in seeking alternatives to sucrose. Trehalulose, a beneficial structural isomer of sucrose, is a non-cariogenic sugar with a low glycemic and insulinemic index. Besides its potential as a sugar substitute, trehalulose exhibits high antioxidant properties, making it attractive for various industrial applications. Despite its numerous advantages and potential application in various sectors, the industrial adoption of trehalulose has yet to be established due to lack of studies on its characteristics and practical uses. This review aims to provide a comprehensive overview of the properties of trehalulose, emphasizing its health benefits. The industrial prospects of trehalulose as sweetener and reducing agent, particularly in food and beverages pharmaceutical, and cosmeceutical sectors, are explored. Additionally, the review delves into the sources of trehalulose and the diverse organisms capable of producing trehalulose. The biosynthesis of this sugar primarily involves an enzyme-mediated process. Thus, these enzymes' properties, mechanisms, and the heterologous expression of genes associated with trehalulose production are explored. The strategies discussed in this review can be improved and applied to establish trehalulose bio-factories for efficient synthesis of trehalulose in the future. With further research and development, trehalulose holds promise as a valuable component across various industries.

Enzymatic Production of Trehalose and Trehalulose by Immobilized Thermostable Trehalose Synthase

Trehalose, a versatile disaccharide renowned for its unique physical and chemical properties, finds extensive application in the food, pharmaceutical, and cosmetic industries. While conventional extraction methods face challenges, enzymatic conversion offers a promising avenue for the industrial production of trehalose. This study delves into a novel synthetic approach utilizing a recombinant enzyme, merging the thermostable trehalose synthase domain from Thermus thermophiles with a cellulose binding domain. Immobilization of this enzyme on cellulose matrices enhances stability and facilitates product purification, opening avenues for efficient enzymatic synthesis. Notably, the engineered enzyme demonstrates additional activity, converting sucrose into trehalulose. This dual functionality, combined with immobilization strategies, holds immense potential for scalable and cost-effective production of trehalose and trehalulose, offering promising prospects in various industrial and biomedical applications.

Structural and Mutational Analyses of Trehalose Synthase from Deinococcus radiodurans Reveal the Interconversion of Maltose-Trehalose Mechanism

Trehalose synthase (TreS) catalyzes the reversible interconversion of maltose to trehalose, playing a vital role in trehalose production. Understanding the catalytic mechanism of TreS is crucial for optimizing the enzyme activity and enhancing its suitability for industrial applications. Here, we report the crystal structures of both the wild type and the E324D mutant of Deinococcus radiodurans trehalose synthase in complex with the trehalose analogue, validoxylamine A. By employing structure-guided mutagenesis, we identified N253, E320, and E324 as crucial residues within the +1 subsite for isomerase activity. Based on these complex structures, we propose the catalytic mechanism underlying the reversible interconversion of maltose to trehalose. These findings significantly advance our comprehension of the reaction mechanism of TreS.

Autophagic-lysosomal damage induced by swainsonine is protected by trehalose through activation of TFEB-regulated pathway in renal tubular epithelial cells

Swainsonine (SW) is the main toxic component of locoweed. Previous studies have shown that kidney damage is an early pathologic change in locoweed poisoning in animals. Trehalose induces autophagy and alleviates lysosomal damage, while its protective effect and mechanism against the toxic injury induced by SW is not clear. Based on the published literature, we hypothesize that transcription factor EB(TFEB) -regulated is targeted by SW and activating TFEB by trehalose would reverse the toxic effects. In this study, we investigate the mechanism of protective effects of trehalose using renal tubular epithelial cells. The results showed that SW induced an increase in the expression level of microtubule-associated protein light chain 3-II and p62 proteins and a decrease in the expression level of ATPase H+ transporting V1 Subunit A, Cathepsin B, Cathepsin D, lysosome-associated membrane protein 2 and TFEB proteins in renal tubular epithelial cells in a time and dose-dependent manner suggesting TFEB-regulated lysosomal pathway is adversely affected by SW. Conversely, treatment with trehalose, a known activator of TFEB promote TFEB nuclear translocation suggesting that TFEB plays an important role in protection against SW toxicity. We demonstrated in lysosome staining that SW reduced the number of lysosomes and increased the luminal pH, while trehalose could counteract these SW-induced effects. In summary, our results demonstrated for the first time that trehalose could alleviate the autophagy degradation disorder and lysosomal damage induced by SW. Our results provide an interesting method for reversion of SW-induced toxicity in farm animals and furthermore, activation of TFEB by trehalose suggesting novel mechanism of treating lysosomal storage diseases.

Characterization of cold-active trehalose synthase from Pseudarthrobacter sp. for trehalose bioproduction

Trehalose is a functional sugar that has numerous applications in food, cosmetic, and pharmaceutical products. Production of trehalose from maltose via a single-step enzymatic catalysis using trehalose synthase (TreS) is a promising method compared with the conventional two-step process due to its simplicity with lower formation of byproducts. In this study, a cold-active trehalose synthase (PaTreS) from Pseudarthrobacter sp. TBRC 2005 was heterologously expressed and characterized. PaTreS showed the maximum activity at 20 °C and maintained 87% and 59% of its activity at 10 °C and 4 °C, respectively. The enzyme had remarkable stability over a board pH range of 7.0-9.0 with the highest activity at pH 7.0. The activity was enhanced by divalent metal ions (Mg2+, Mn2+ and Ca2+). Conversion of high-concentration maltose syrup (100-300 g/L) using PaTreS yielded 71.7-225.5 g/L trehalose, with 4.5-16.4 g/L glucose as a byproduct within 16 h. The work demonstrated the potential of PaTreS as a promising biocatalyst for the development of low-temperature trehalose production, with the advantages of reduced risk of microbial contamination with low generation of byproduct.

Trehalose Production Using Three Extracellular Enzymes Produced via One-Step Fermentation of an Engineered Bacillus subtilis Strain

At present, the double-enzyme catalyzed method using maltooligosyltrehalose synthase (MTSase) and maltooligosyltrehalose trehalohydrolase (MTHase) is the mainstream technology for industrial trehalose production. However, MTSase and MTHase are prepared mainly using the heterologous expression in the engineered Escherichia coli strains so far. In this study, we first proved that the addition of 3 U/g neutral pullulanase PulA could enhance the trehalose conversion rate by 2.46 times in the double-enzyme catalyzed system. Then, a CBM68 domain was used to successfully assist the secretory expression of MTSase and MTHase from Arthrobacter ramosus S34 in Bacillus subtilis SCK6. At the basis, an engineered strain B. subtilis PSH02 (amyE::pulA/pHT43-C68-ARS/pMC68-ARH), which co-expressed MTSase, MTHase, and PulA, was constructed. After the 24 h fermentation of B. subtilis PSH02, the optimum ratio of the extracellular multi-enzymes was obtained to make the highest trehalose conversion rate of 80% from 100 g/L maltodextrin. The high passage stability and multi-enzyme preservation stability made B. subtilis PSH02 an excellent industrial production strain. Moreover, trehalose production using these extracellular enzymes produced via the one-step fermentation of B. subtilis PSH02 would greatly simplify the procedure for multi-enzyme preparation and be expected to reduce production costs.

Therapeutic potential of natural compounds from herbs and nutraceuticals in spinal cord injury: Regulation of the mTOR signaling pathway

Spinal cord injury (SCI) is a disease in which the spinal cord is subjected to various external forces that cause it to burst, shift, or, in severe cases, injure the spinal tissue, resulting in nerve injury. SCI includes not only acute primary injury but also delayed and persistent spinal tissue injury (i.e., secondary injury). The pathological changes post-SCI are complex, and effective clinical treatment strategies are lacking. The mammalian target of rapamycin (mTOR) coordinates the growth and metabolism of eukaryotic cells in response to various nutrients and growth factors. The mTOR signaling pathway has multiple roles in the pathogenesis of SCI. There is evidence for the beneficial effects of natural compounds and nutraceuticals that regulate the mTOR signaling pathways in a variety of diseases. Therefore, the effects of natural compounds on the pathogenesis of SCI were evaluated by a comprehensive review using electronic databases, such as PubMed, Web of Science, Scopus, and Medline, combined with our expertise in neuropathology. In particular, we reviewed the pathogenesis of SCI, including the importance of secondary nerve injury after the primary mechanical injury, the roles of the mTOR signaling pathways, and the beneficial effects and mechanisms of natural compounds that regulate the mTOR signaling pathway on pathological changes post-SCI, including effects on inflammation, neuronal apoptosis, autophagy, nerve regeneration, and other pathways. This recent research highlights the value of natural compounds in regulating the mTOR pathway, providing a basis for developing novel therapeutic strategies for SCI.

Metagenomic Approaches as a Tool to Unravel Promising Biocatalysts from Natural Resources: Soil and Water

Natural resources are considered a promising source of microorganisms responsible for producing biocatalysts with great relevance in several industrial areas. However, a significant fraction of the environmental microorganisms remains unknown or unexploited due to the limitations associated with their cultivation in the laboratory through classical techniques. Metagenomics has emerged as an innovative and strategic approach to explore these unculturable microorganisms through the analysis of DNA extracted from environmental samples. In this review, a detailed discussion is presented on the application of metagenomics to unravel the biotechnological potential of natural resources for the discovery of promising biocatalysts. An extensive bibliographic survey was carried out between 2010 and 2021, covering diverse metagenomic studies using soil and/or water samples from different types and locations. The review comprises, for the first time, an overview of the worldwide metagenomic studies performed in soil and water and provides a complete and global vision of the enzyme diversity associated with each specific environment.