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Background d -tagatose is regarded as one of the most valuable rare sugars in the current market and its biotechnological ways of production is a very hot topic as of today. As a ketohexose, d -tagatose having low-caloric value and 90% of sweetness with sucrose is a rare monosaccharide that exists extremely in low quantities in nature. Owing to distinct properties and beneficial functions on human health it has received a great interest and attained Generally Recognised as Safe (GRAS) status by the U.S. Food and Drug Administration (USFDA) in 2010. Scope and approach Due to scarcity in nature, production of d -tagatose either by chemical or biological methods is of utmost importance. In order to overcome the challenges that occur in chemical production, recently, biological process by using l -arabinose isomerase (L-AIs) for converting d -galactose to d -tagatose has allured researchers to find out more new ways to synthesize it in a cheap and eco-friendly manner. Herein, a brief summary on the scope of enzyme engineering methods like rational, semi-rational and directed evolution approaches to generate tailored L-AIs for improving d -tagatose yield and its function under harsh conditions are summarized. In addition, comparison of biochemical parameters and structural key aspects are also highlighted in this paper. Key findings and conclusions Till date, L-AIs from various microbial sources are identified and characterized. Elucidating crystal structures and catalytic mechanism has elevated the researcher's interest to modify the L-AIs at molecular level and demonstrate its potential that is suited for industrial settings. However, works to produce d -tagatose from cheap renewable feedstocks and methods like immobilization and cell-surface display of L-AIs for efficient uptake and biotransformation of d -galactose are scarcely reported. In future, by employing the aforementioned strategies, the research studies must be focused more on shaping L-AIs as powerful biocatalysts to produce d -tagatose at industrial scale that necessitates for the human welfare.

As a substitute sweetener for sucrose, d‐tagatose is widely used in products, such as health drinks, yogurt, fruit juices, baked goods, confectionery, and pharmaceutical preparations. In the fermentation process of l‐AI produced by Lactobacillus plantarum, d‐tagatose is produced through biotransformation and this study was based on the fermentation process of Lactobacillus plantarum WU14 producing l‐AI to further research the biotransformation and separation process of d‐tagatose. The kinetics of cell growth, substrate consumption, and l‐arabinose isomerase formation were established by nonlinear fitting, and the fitting degrees were 0.996, 0.994, and 0.991, respectively, which could better reflect the change rule of d‐tagatose biotransformation in the fermentation process of L. plantarum WU14. The separation process of d‐tagatose was identified by decolorization, protein removal, desalination, and freeze drying, initially. Finally, the volume ratio of whole cell catalysts, d‐galactose, and borate was 5:1:2 at 60°C, pH 7.17 through borate complexation; then, after 24 hr of conversion, the yield of d‐tagatose was 58 g/L., Lactobacillus plantarum WU14 was isolated from sauerkraut, and it has high ability to transform d‐tagatose by l‐arabinose isomerase. On the base of the fermentation medium optimization of l‐AI produced by L. plantarum WU14, a mathematical model was established, and d‐tagatose was separated from the fermentation broth. The Logistic equation and the Boltzmann model were used to nonlinearly fit the experimental data of L. plantarum WU14 biomass and l‐AI activity. It was found that when the conversion temperature was 60°C, the reaction pH was 7.17, the volume ratio of the crude enzyme solution to the d‐galactose was 5:1, and the volume ratio of borate to d‐galactose was 2:1. After 24 hr of conversion, the conversion of d‐tagatose was increased 12%.

d-Tagatose, a low-calorie functional sweetener, is biotransformed from lactose via galactose. The discovery of an enzyme with 4-epimerization activity toward d-fructose to produce d-tagatose has be...

1** İstanbul Sabahattin Zaim Üniversitesi, Mühendislik Fakültesi, Gıda Mühendisliği Bölümü, İstanbul, Türkiye, (ORCID: 0000-0002-5388-5856), hasan.yetim@izu.edu.tr -- 2 İstanbul Sabahattin Zaim Üniversitesi, Helal Gıda Ar-Ge Merkezi, İstanbul, Türkiye -- 3 İstanbul Sabahattin Zaim Üniversitesi, Sağlık Bilimleri Fakültesi, Beslenme ve Diyetetik Bölümü, İstanbul, Türkiye, (ORCID: 0000-0002-7248-2446), ismail.tekiner@izu.edu.tr -- 4 İstanbul Sabahattin Zaim Üniversitesi, Lisansüstü Eğitim Enstitüsü, Gıda ve Beslenme Bölümü, İstanbul, Türkiye Tagatoz, genellikle süt ürünlerinde bulunan doğal ve altı karbonlu bir monosakkarit (ketoheksoz) şekerdir. İlk defa Gilbert Levin tarafından elde edilen Tagatozun tatlılık derecesi sükroza yakın ve kalorisi düşüktür. FAO ve WHO tarafından 2001 yılından itibaren güvenilir kabul edilen D-Tagatoz (D-tag), son yıllarda artan şeker tüketimine bağlı obezite, diyabet, ağız sağlığı ve sindirim sistemi sorunlarına karşı alternatif bir tatlandırıcı olarak öne çıkmaktadır. Bu ilginin temelinde ise Tagatozun sükroza oranla daha az metabolize edilmesi, ince bağırsakta daha düşük emilimi, kolon mikroflorası tarafından fermente edilebilmesi, antihiperglisemik oluşu, prebiyotik olarak gut sağlığını pozitif anlamda desteklemesi ile vücuttan idrar yoluyla uzaklaştırılabilmesi bulunmaktadır. Ayrıca, araştırmalar, Dtagatozun genotoksik etkisi olmadığını da göstermektedir. Glisemik indeksi düşük ve antidiyabetik etkisi olduğu kabul edilen DTagatozun doğal kaynakları dışında ticari olarak daha yüksek miktarlarda elde edilmesi, süt şekeri laktozun yapı taşı galaktozun, enzimatik ya da alkali izomerizasyonu ile sağlanmaktadır. Tagatoz üretimi amacıyla kullanılan ve Dünya süt ve süt ürünleri sektörünün en önemli yan ürünlerinden peynir altı suyunun yıllık üretimi 200 milyon ton civarındadır. Buradan üretilen süt şekeri galaktozun (laktozun parçalanma ürünü) ticari D-Tagatoza dönüştürülmesi, gıda sektörü için önemli bir çıkış yolu olarak görülmektedir. Sağlıklı ve doğal beslenme açısından getireceği faydaların dışında Dünya yapay tatlandırıcı pazarı büyüklüğünün 3.2 milyar dolar olduğu gerçeği de göz önüne alınırsa D-tagatozun, alternatif tatlandırıcı ve prebiyotik sektörleri için itici bir güç olacağını ifade etmek hatalı olmayacaktır. Ayrıca, son çalışmalar, D-Tagatozun tarım sektöründe bitki hastalıkları ile mücadelede antifungal agrokimyasal olarak kullanılabileceğini de göstermektedir. Sonuç olarak, bu çalışmada, D-tagatozun gıda mühendisliği ve beslenme bilimleri açısından yeri, önemi ve potansiyel uygulama alanlarının değerlendirilmesi amaçlanmıştır. Tagatose is a naturally occurring six-carbon monosaccharide (ketohexose), which is generally found in dairy products. It was first proposed by Gilbert Levin, and has a similar texture to sucrose with a lower calorific value. D-Tagatose (D-tag) has recognized as safe status by FAO and WHO since 2001, and therefore gained significant attention in the recent years as an alternative sweetener for some health issues linked to excess sugar consumtion, including obesity, diabete, oral (tooth) health and gastrointestinal symptoms. On the basis of this interest, it has some advantageous characteristics, compared to sucrose, like lower metabolic activity, slow and incomplete absorption in the small intestine, low fermentability in the colon by microflora, antihyperglisemic, prebiotic promoting gut health, and easy-excretion from body via urine. Furthermore, the researches demonstrates that D-Tagatose has no genotoxic effect. D-Tagatose, an antidiabetic with low glycemic index, can also be obtained from the enzymatic or alkali isomerization of the milk sugars, galactose in high quantities commercially, other than natural sources. The whey is a by-product of the global milk and dairy sector with an annual production quantity of 200 million tonnes, and considered a potential raw-source for manufacturing tagatose. The conversion of milk sugar, galactose, into commercial D-tagatose therefore offers a way-out for the food industry. Except for its healthy and natural nutritional benefits, based on the fact that the global market of artificial sweeteners around 3.2 billion dollars, D-tagatose can play a pivotal role as a driving force for alternative sweeteners and prebiotic sector. In addition to that, the recent studies have indicated that D-tagatose can also be utilized as an agro-chemical to control fungal plant diseases in the agro-sector. Overall, the objective of this study was to evaluate the role, value and potential areas of application in both food engineering and nutritional sciences.

Recent studies have shown phenotypic and metabolic heterogeneity in related species including Streptococcus oralis, a typical oral commensal bacterium, Streptococcus mutans, a cariogenic bacterium, and Streptococcus gordonii, which functions as an accessory pathogen in periodontopathic biofilm. In this study, metabolites characteristically contained in the saliva of individuals with good oral hygiene were determined, after which the effects of an identified prebiotic candidate, D-tagatose, on phenotype, gene expression, and metabolic profiles of those three key bacterial species were investigated. Examinations of the saliva metabolome of 18 systemically healthy volunteers identified salivary D-tagatose as associated with lower dental biofilm abundance in the oral cavity (Spearman’s correlation coefficient; r = -0.603, p = 0.008), then the effects of D-tagatose on oral streptococci were analyzed in vitro. In chemically defined medium (CDM) containing D-tagatose as the sole carbohydrate source, S. mutans and S. gordonii each showed negligible biofilm formation, whereas significant biofilms were formed in cultures of S. oralis. Furthermore, even in the presence of glucose, S. mutans and S. gordonii showed growth suppression and decreases in the final viable cell count in a D-tagatose concentration-dependent manner. In contrast, no inhibitory effects of D-tagatose on the growth of S. oralis were observed. To investigate species-specific inhibition by D-tagatose, the metabolomic profiles of D-tagatose-treated S. mutans, S. gordonii, and S. oralis cells were examined. The intracellular amounts of pyruvate-derived amino acids in S. mutans and S. gordonii, but not in S. oralis, such as branched-chain amino acids and alanine, tended to decrease in the presence of D-tagatose. This phenomenon indicates that D-tagatose inhibits growth of those bacteria by affecting glycolysis and its downstream metabolism. In conclusion, the present study provides evidence that D-tagatose is abundant in saliva of individuals with good oral health. Additionally, experimental results demonstrated that D-tagatose selectively inhibits growth of the oral pathogens S. mutans and S. gordonii. In contrast, the oral commensal S. oralis seemed to be negligibly affected, thus highlighting the potential of administration of D-tagatose as an oral prebiotic for its ability to manipulate the metabolism of those targeted oral streptococci.

Food manufacturers are under increasing pressure to limit the amount of free sugars in their products. Many have reformulated products to replace sucrose, glucose and fructose with alternative sweeteners, but some of these have been associated with additional health concerns. Rare sugars are ‘monosaccharides and their derivatives that hardly exist in nature’, and there is increasing evidence that they could have health benefits. This review aimed to scope the existing literature in order to identify the most commonly researched rare sugars, to ascertain their proposed health benefits, mechanisms of action and potential uses and to highlight knowledge gaps. A process of iterative database searching identified fifty-five relevant articles. The reported effects of rare sugars were noted, along with details of the research methodologies conducted. Our results indicated that the most common rare sugars investigated are d-psicose and d-tagatose, with the potential health benefits divided into three topics: glycaemic control, body composition and CVD. All the rare sugars investigated have the potential to suppress postprandial elevation of blood glucose and improve glycaemic control in both human and animal models. Some animal studies have suggested that certain rare sugars may also improve lipid profiles, alter the gut microbiome and reduce pro-inflammatory cytokine expression. The present review demonstrates that rare sugars could play a role in reducing the development of obesity, type 2 diabetes and/or CVD. However, understanding of the mechanisms by which rare sugars may exert their effects is limited, and their effectiveness when used in reformulated products is unknown.

d-tagatose is a rare monosaccharide, naturally present at low concentrations in some fruits and dairy products.d-tagatose is "generally recognized as safe" and is used as a low-calorie sweetener in the food industry.It is able to inhibit the growth of numerous microorganisms, such as phytopathogenic oomycetes responsible for important crop diseases. Thanks to the negligible effects on human health and the environment,d-tagatose has been proposed as a sustainable product for crop protection. This review describes the current knowledge on modes of action ofd-tagatose against phytopathogenic oomycetes and its potential uses in agriculture.d-tagatose can negatively affect the growth of phytopathogenic oomycetes by inhibiting key enzymes of sugar metabolism, such as β-glucosidase inPhytophthora infestans, and fructokinase and phosphomannose isomerase inHyaloperonospora arabidopsidis. Moreover,d-tagatose affects sugar content, causes severe mitochondrial alterations, and inhibits respiration processes with the accumulation of reactive oxygen species inP.infestans, but not inP.cinnamomi. Differential effects ofd-tagatose are associated with a global gene downregulation inP.infestansand with an efficient transcriptional reprogramming of multiple metabolic processes inP.cinnamomi.d-tagatose displays possible species-specific effects inPhytophthoraspp. and nutritional properties on some plant-associated microorganisms. However, inhibitory effects are reversible andP.infestansgrowth can be restored in the absence ofd-tagatose. Further functional studies are discussed in this review, in order to promote the use ofd-tagatose for sustainable crop protection.

D-tagatose 1,6-diphosphate is an important metabolite which can be formed via the classical tagatose 6-phosphate pathway or via the tagatose 1-phosphate pathway discovered more recently. Th...

Aims: D-tagatose is a natural ketohexose which can be used as a functional sweetener in foods, diary and beverages products. Isolation of new bacterial strains having the ability to produce D-tagatose is a continuously trending topic of research. Study Design: Screening of strains with D-tagatose production by identification and determination of its ability to produce D-tagatose content. Place and Duration of Study: School of Food and Biological Engineering, Jiangsu University between May 2018 and April 2019. Methodology: We initially screened and identified the strains capable of producing D-tagatose through kimchi liquid, and determined the species and genetic characteristics of the strain by physiological, biochemical and molecular biological identification, and then determined the content of D-tagatose by high performance liquid chromatography. Finally calculate the ability of the strain to produce D-tagatose. Results: In this study, 4 strains of lactic acid bacteria (LAB) were isolated from kimchi sample. The isolates were identified as Lactobacillus spp. (Lactobacillus plantarum, Lactobacillus fermentum and Lactobacillus salivarius) on the basis of morphological, physicochemical characteristics and analysis of 16S rDNA gene sequence. Because of the novelty, strain designated as L. salivarius UJS 003 was considered for D-tagatose yield. Fermentation of D-tagatose was carried out using galactose as substrate for 48 hr at 37 °C, and HPLC method was used to determine the yield. The experimental results exhibited a D-tagatose yield of 3.134 g/L by L. salivarius UJS 003. Conclusion: The strain UJS 003 represented as a potent D-tagatose producer and could be useful in a variety of biotechnological and industrial processes, particularly food and beverage industries.

This study reports an alternative strategy for the expression of a recombinant L-AI from Enterococcus faecium DBFIQ E36 by auto-induction using glucose and glycerol as carbon sources and residual whey lactose as inducer agent. Commercial lactose and isopropyl β-D-1-thiogalactopyranoside (IPTG) were also evaluated as inducers for comparison of enzyme expression levels. The enzymatic extracts were purified by affinity chromatography, characterized, and applied in the bioconversion of D-galactose into D-tagatose. L-AI presented a catalytic activity of 1.67 ± 0.14, 1.52 ± 0.01, and 0.7 ± 0.04 U/mL, when expressed using commercial lactose, lactose from whey, and IPTG, respectively. Higher activities could be obtained by changing the protocol of enzyme extraction and, for instance, the enzymatic extract produced with whey presented a catalytic activity of 3.8 U/mL. The specific activity of the enzyme extracts produced using lactose (commercial or residual whey) after enzyme purification was also higher when compared to the enzyme expressed with IPTG. Best results were achieved when enzyme expression was conducted using 4 g/L of residual whey lactose for 11 h. These results proved the efficacy of an alternative and economic protocol for the effective expression of a recombinant L-AI aiming its high-scale production.

[EN] D-Tagatose is one of the most promising functional sweeteners, this sugar is able to modulate lipid metabolism, and reduce the symptoms associated with type 2 diabetes. This Thesis is focused on the development of a totally biocatalytic methodology for obtaining D-tagatose. First step was the hydrolysis of whey permeate with a novel commercial β-galactosidase from Bifidobacterium bifidum (Saphera). For second step, two different approaches were proposed for the transformation/elimination of D-glucose. First one was with a glucose isomerase from Caldicoprobacter algeriensis to transform D-glucose into D-fructose. This enzyme was successfully immobilized and used in a packed bead bioreactor with a productivity of 1080 g L-1 day-1. Pichia pastoris was the second option for the treatment of whey permeate; this microorganism was able of completely eliminate D-glucose. P. pastoris was immobilized with alginate, efficiently reused for 13 cycles. Isomerization of D-galactose was performed with a L-arabinose isomerase from Bacillus stearothermophilus. The enzyme was successfully immobilized in a polymethacrylate support. A packed bed bioreactor was developed, with an initial productivity of D-tagatose of 77 g L-1 day-1. Next step was the search of a microorganism able to consume D-galactose without consuming D-tagatose. From 19 microorganisms tested, the best was Schwanniomyces occidentalis. This microorganism was immobilized with alginate and this biocatalyst could be reused for 3 cycles of 5 h each. Finally a sequential reaction was performed, starting with whey as lactose source. Showing that it is possible to obtain D-tagatose using an industrial waste as starting reagent, following a completely biocatalytic methodology., [ES] D-Tagatosa es un edulcorante funcional muy prometedor; este es capaz de modular el metabolismo de lípidos y reducir los síntomas asociados con la diabetes tipo 2. Esta Tesis se centra en el desarrollo de una metodología totalmente biocatalítica para la obtención de D-tagatosa. El primer paso fue la hidrólisis del permeato de suero con una β-galactosidasa comercial de Bifidobacterium bifidum (Saphera). Para el segundo paso de transformación/eliminación de la D-glucosa, se propusieron dos enfoques. En el primero se usó una glucosa isomerasa de Caldicoprobacter algeriensis para transformar D-glucosa en D-fructosa. Esta enzima se inmovilizó con éxito y se utilizó en un biorreactor con una productividad de 1080 g L-1 día-1. La segunda opción fue el uso de Pichia pastoris, este microorganismo fue capaz de eliminar completamente la D-glucosa; se inmovilizó con alginato y se reutilizó eficazmente durante 13 ciclos. Para isomerizar D-galactosa, se utilizó la L-arabinosa isomerasa de Bacillus stearothermophilus. La enzima se inmovilizó con éxito en un soporte de polimetacrilato y se utilizó en un biorreactor, con productividad inicial de D-tagatosa de 77 g L-1 día-1. Se realizó la búsqueda de un microorganismo capaz de consumir D-galactosa sin consumir D-tagatosa. De los 19 microorganismos analizados, el mejor fue Schwanniomyces occidentalis. Se inmovilizó en alginato y se logró reusar durante 3 ciclos de 5 h cada uno. Finalmente realizamos una reacción secuencial usando suero como fuente de lactosa. Demostramos que es posible obtener D-tagatosa utilizando un residuo industrial como reactivo de partida, siguiendo una metodología completamente biocatalítica., Consejo Nacional de Ciencia y Tecnología de México (CONACYT)

We examined the effect of D-Tagatose on the growth of oral bacteria including Streptococcus mutans (S. mutans). Saliva collected from 10 healthy volunteers was plated on BHI medium (to culture total oral bacteria) and MBS medium (to culture S. mutans, specifically). Agar plates of BHI or MBS containing xylitol or D-Tagatose were cultured under aerobic or anaerobic conditions. We then counted the number of colonies. In BHI plates containing D-Tagatose, a complete and significant reduction of bacteria occurred under both aerobic and anaerobic conditions. In MSB medium, significant reduction of S. mutans was also observed. We then performed a doubleblind parallel randomized trial with 19 healthy volunteers. They chewed gum containing xylitol, D-Tagatose, or both for 4 weeks, and their saliva was collected weekly and plated on BHI and MSB media. These plates were cultured under anaerobic conditions. Total bacteria and S. mutans were not effectively reduced in either the D-Tagatose or xylitol gum group. However, S. mutans was significantly reduced in volunteers chewing gum containing both D-Tagatose and xylitol. Thus, D-Tagatose inhibited the growth of S. mutans and many types of oral bacteria, indicating that D-Tagatose intake may help prevent dental caries, periodontitis, and many oral diseases.

D-Galactose-specific L-arabinose isomerase (L-AI) would have much potential for the enzymatic conversion of D-Galactose into D-tagatose, while most of the reported L-AIs are L-arabinose specific. This study explored a highly D-Galactose-specific L-AI from Bifidobacterium adolescentis (BAAI) for the production of D-tagatose. In the comparative protein-substrate docking for D-Galactose and L-arabinose, BAAI showed higher numbers of hydrogen bonds in D-Galactose-BAAI bonding site than those found in L-arabinose-BAAI bonding site. The activity of BAAI was 24.47 U/mg, and it showed good stability at temperatures up to 65°C and a pH range 6.0-7.5. The K m, V max, and K cat/K m of BAAI were found to be 22.4 mM, 489 U/mg and 9.3 mM-1 min-1, respectively for D-Galactose, while the respective values for L-arabinose were 40.2 mM, 275.1 U/mg, and 8.6 mM-1 min-1. Enzymatic conversion of D-Galactose into D-tagatose by BAAI showed 56.7% conversion efficiency at 55°C and pH 6.5 after 10 h.

Nutraceuticals are gaining importance owing to their potential applications in numerous sectors including food and feed industries. Among the emerging nutraceuticals, d-tagatose occupies a significant niche because of its low calorific value, antidiabetic property and growth promoting effects on beneficial gut bacteria. As d-tagatose is present in minute quantities in naturally occurring food substances, it is produced mainly by chemical or biological means. Recently, attempts were made for bio-production of d-tagatose using l-arabinose isomerase enzyme to overcome the challenges of chemical process of production. Applications of d-tagatose for maintaining health and wellbeing are increasing due to growing consumer awareness and apprehension against modern therapeutic agents. This review outlines the current status on d-tagatose, particularly its production, properties, biological role, applications, and the future perspectives.

In this study, the bio-oxidation of galactitol to the valuable D-tagatose is presented. This proposed strategy could start with the refined by-product of waste xylose mother liquor formed by chemical hydrogenation. Through a computationally guided enzyme screening approach, a robust polyol dehydrogenase (PdPDH) was rapidly identified from a massive number of candidates. When coupled with a water-forming NADH oxidase (StNOX) for environmentally benign cofactor regeneration, subsequent reaction optimization facilitated the complete transformation of 100 g L−1 galactitol into the desired product within 15 h, with a yield of 91% in a 2 L scale preparative reaction. Compared to the current enzymatic isomerization system, our approach avoids low conversion, high operative temperatures and by-product formation, while enabling simplified product isolation.

Indexación: Scopus. The objective of the current research was to review and update evidence on the dietary effect of the consumption of tagatose in type 2 diabetes, as well as to elucidate the current approach that exists on its production and biotechnological utility in functional food for diabetics. Articles published before July 1, 2017, were included in the databases PubMed, EBSCO, Google Scholar, and Scielo, including the terms "Tagatose", "Sweeteners", "Diabetes Mellitus type 2", "Sweeteners", "D-Tag". D-Tagatose (D-tag) is an isomer of fructose which is approximately 90% sweeter than sucrose. Preliminary studies in animals and preclinical studies showed that D-tag decreased glucose levels, which generated great interest in the scientific community. Recent studies indicate that tagatose has low glycemic index, a potent hypoglycemic effect, and eventually could be associated with important benefits for the treatment of obesity. The authors concluded that D-tag is promising as a sweetener without major adverse effects observed in these clinical studies. https://www.hindawi.com/journals/bmri/2018/8718053/

A concise, easily scalable synthesis of a rare ketohexose, d -tagatose, was developed, that is compatible with the preparation of d -[UL-13C6]tagatose. Epimerization of the widely available and inexpensive ketohexose d -fructose at the C-4 position via an oxidation/reduction (Dess-Martin periodinane/NaBH4) was a key step in the synthesis. Overall, fully protected natural d -tagatose (3.21 g) was prepared from d -fructose (9 g) on a 50 mmol scale in 23% overall yield, after five steps and two chromatographic purifications. d -[UL-13C6]Tagatose (92 mg) was prepared from d -[UL-13C6]fructose (465 mg, 2.5 mmol) in 16% overall yield after six steps and four chromatographic purifications.

The rapid increase of agricultural waste is becoming a burgeoning problem and considerable efforts are being made by numerous researchers to convert it into a high-value resource material. Onion waste is one of the biggest issues in a world of dwindling resource. In this study, the potential of onion juice residue (OJR) for producing valuable rare sugar or bioethanol was evaluated. Purified Paenibacillus polymyxaL-arabinose isomerase (PPAI) has a molecular weight of approximately 53kDa, and exhibits maximal activity at 30°C and pH 7.5 in the presence of 0.8mM Mn2+. PPAI can produce 0.99g D-tagatose from 10g OJR. In order to present another application for OJR, we produced 1.56g bioethanol from 10g OJR through a bioconversion and fermentation process. These results indicate that PPAI can be used for producing rare sugars in an industrial setting, and OJR can be converted to D-tagatose and bioethanol.

D-tagatose is a naturally existing rare monosaccharide having prebiotic properties. Minimal absorption, low metabolizing energy, and unique clinical properties are the characteristics of D-tagatose. D-tagatose gained international attention by matching the purpose of alternate sweeteners that is much needed for the control of diabetes among world population. Recent efforts in understanding tagatose bioconversion have generated essential information regarding its production and application. This article reviews the evolution of D-tagatose as an important rare sugar by appreciable improvements in production results and its significant applications resulted of its unique physical, chemical, biological, and clinical properties thus considering it an appropriate product for requisite improvements in technical viability. Based on current knowledge and technology projections, the commercialization of D-tagatose rare sugar as food additive is close to reality.

Rare sugars can find applications in various industrial sectors and, therefore, hold significant economic value. Due to their low natural abundance, efficient production processes are needed to enable their commercial exploitation. About a decade ago, the available biosynthetic routes were summarized in the so-called “Izumoring”, which mainly comprised reactions catalysed by keto-aldol isomerases and oxidoreductases. Although just a single epimerase specificity (acting on the 3-position of ketoses) was included, these enzymes hold the potential to truly revolutionize the field as they offer shortcuts in conversion processes. For example, C2-epimerases could replace double isomerization reactions, whereas C4/5-epimerases could form a new bridge between d- and l-sugars as alternative to the current two-step oxidoreduction reaction. Here, we present the “Epimerring” to highlight the potential of new epimerases that can still be discovered and/or engineered, which may open doors to new and improved sy...

A recombinant L-arabinose isomerase from Enterococcus faecium DBFIQ E36 was immobilized onto multifunctional epoxide supports by chemical adsorption and onto a chelate-activated support via polyhistidine-tag, located on the N-terminal (N-His-L-AI) or on the C-terminal (C-His-L-AI) sequence, followed by covalent bonding between the enzyme and the support. The results were compared to reversible L-AI immobilization by adsorption onto charged agarose supports with improved stability. All the derivatives presented immobilization yields of above 75%. The ionic interaction established between agarose gels containing monoaminoethyl-N-aminoethyl structures (MANAE) and the enzyme was the most suitable strategy for L-AI immobilization in comparison to the chelate-activated agarose. In addition, the immobilized biocatalysts by ionic interaction in MANAE showed to be the most stable, retaining up to 100% of enzyme activity for 60 min at 60 °C and with Km values of 28 and 218 mM for MANAE-N-His-L-AI and MANAE-C-His-L-AI, respectively., This study received financial support from the Brazilian Research Agencies CAPES, CNPq, and FUNCAP. This work was partially sponsored by funds from the project Argentina–Brazil Bilateral Cooperation Program BR/12/06 MINCyT-CAPES 2012 (Buenos Aires, Argentina).

An unknown d-tagatose 3-epimerase (DTE) containing a IoIE domain was identified and cloned from Escherichia coli. This gene was subcloned into the prokaryotic expression vector pET-15b, and induced by IPTG in E. coli BL21 expression system. Through His-select gel column purification and fast-protein liquid chromatography, highly purified and stable DTE protein was produced. The molecular weight of the DTE protein was estimated to be 29.8kDa. The latest 83 DTE sequences from public database were selected and analyzed by molecular clustering, multi-sequence alignment. DTEs were roughly divided into five categories.

Rare sugars are monosaccharides that do not occur in nature in large amounts. However, many of them demonstrate high potential as low-calorie sweetener, chiral building blocks or active pharmaceutical ingredients. Their production by enzymatic means from broadly abundant epimers is an attractive alternative to synthesis by traditional organic chemical means, but often suffers from low space-time yields and high enzyme costs due to rapid enzyme degradation. Here we describe the detailed characterization of two variants of d-tagatose epimerase under operational conditions that were engineered for high stability and high catalytic activity towards the epimerization of d-fructose to d-psicose and l-sorbose to l-tagatose, respectively. A variant optimized for the production of d-psicose showed a very high total turnover number (TTN) of up to 108 catalytic events over a catalyst's lifetime, determined under operational conditions at high temperatures in an enzyme-membrane reactor (EMR). Maximum space-time yields as high as 10.6 kg L−1 d−1 were obtained with a small laboratory-scale EMR, indicating excellent performance. A variant optimized for the production of l-tagatose performed less stable in the same setting, but still showed a very good TTN of 5.8 × 105 and space-time yields of up to 478 g L−1 d−1. Together, these results confirm that large-scale enzymatic access to rare sugars is feasible. Biotechnol. Bioeng. 2016;113: 349–358. © 2015 Wiley Periodicals, Inc.

D-Tagatose is a ketohexose monosaccharide and recognized as a low-calorie substitute sweetener that could be used in nonchronic drugs, foods, beverages and dietary supplements. Currently, the biological production of D-tagatose using L-arabinose isomerase has caused extensive attention. In the article, properties and recent researches about D-tagatose and L-arabinose isomerase are described. The industrial application and existing problems are also stated.

Chocolate is dense suspension of solid particles comprising 60-70% sugar and non-fat cocoa solids. Until recently, it was rarely produced as a sugar-free product due to the multi-functional properties of sweetness, bulkiness and textural characteristics that sugar offers to products. Today's consumers are concerned about the high sugar levels, calories and cariogenicity effects in confectionery products, hence increasing popularity of 'light' and 'sugar-free' products. Development of sugar-free chocolates is most challenging since all sugar needs to be replaced. In-depth understanding of the applicability of alternative sweeteners and carbohydrate polymers as ingredients in sugar-free chocolate manufacture would therefore have significant industrial applications.

L-Arabinose isomerase from Bacillus thermoglucosidasius KCTC 1828 (BTAI) was expressed in Escherichia coli. The optimal temperature and pH for the activity of the purified BTAI were 40 °C and pH 7.0. The Mn(2+) ion was an activator of BTAI activity. The kinetic parameters of BTAI for D-galactose were a K(m) of 175 mM and a k(cat)/K(m) of 2.8 mM(-1)min(-1). The conversion ratio by BTAI to D-tagatose reached 45.6% at 40 °C.

Objective This study tests the hypothesis that BSN723T can prevent the development of hyperlipidemia and atherosclerosis in ApoE-/- knockout mice fed a Western (high fat, high cholesterol, and high sucrose) diet. BSN723T is a combination drug therapy consisting of D-tagatose and dihydromyricetin (BSN723). Background D-tagatose has an antihyperglycemic effect in animal and human studies and shows promise as a treatment for type 2 diabetes and obesity. Many claims regarding BSN723's pharmacological activities have been made including anti-cancer, anti-diabetic, anti-hypertensive, anti-inflammatory, and anti-atherosclerotic effects. To our knowledge this is the first study that combines D-tagatose and BSN723 for the treatment of hyperlipidemia and the prevention of atherosclerosis. Methods ApoE-deficient mice were randomized into five groups with equivalent mean body weights. The mice were given the following diets for 8 weeks: Group 1 - Standard diet; Group 2 - Western diet; Group 3 - Western diet formulated with D-tagatose; Group 4 - Western diet formulated with BSN723; Group 5 - Western diet formulated with BSN723T. Mice were measured for weight gain, tissue and organ weights, total serum cholesterol and triglycerides and formation of atherosclerosis. Results The addition of D-tagatose, either alone or in combination with BSN723, prevented the increase in adipose tissue and weight gain brought on by the Western diet. Both D-tagatose and BSN723 alone reduced total cholesterol and the formation of atherosclerosis in the aorta compared to mice on the Western diet. Addition of BSN723 to D-tagatose (BSN723T) did not increase efficacy in prevention of increases in cholesterol or atherosclerosis compared to D-tagatose alone. Conclusion Addition of either D-tagatose or BSN723 alone to a Western diet prevented weight gain, increases in total serum cholesterol and triglycerides, and the formation of atherosclerosis. However, there was no additive or synergistic effect on the measured parameters with the combination BSN723T treatment.

Background L-arabinose isomerase (AI) is a crucial catalyst for the biotransformation of D-galactose to D-tagatose. In previous reports, AIs from thermophilic bacterial strains had been wildly researched, but the browning reaction and by-products formed at high temperatures restricted their applications. By contrast, AIs from mesophilic Bacillus strains have some different features including lower optimal temperatures and lower requirements of metallic cofactors. These characters will be beneficial to the development of a more energy-efficient and safer production process. However, the relevant data about the kinetics and reaction properties of Bacillus AIs in D-tagatose production are still insufficient. Thus, in order to support further applications of these AIs, a comprehensive characterization of a Bacillus AI is needed. Results The coding gene (1422 bp) of Bacillus coagulans NL01 AI (BCAI) was cloned and overexpressed in the Escherichia coli BL21 (DE3) strain. The enzymatic property test showed that the optimal temperature and pH of BCAI were 60 °C and 7.5 respectively. The raw purified BCAI originally showed high activity in absence of outsourcing metallic ions and its thermostability did not change in a low concentration (0.5 mM) of Mn2+ at temperatures from 70 °C to 90 °C. Besides these, the catalytic efficiencies (kcat/Km) for L-arabinose and D-galactose were 8.7 mM-1 min-1 and 1.0 mM-1 min-1 respectively. Under optimal conditions, the recombinant E. coli cell containing BCAI could convert 150 g L-1 and 250 g L-1 D-galactose to D-tagatose with attractive conversion rates of 32 % (32 h) and 27 % (48 h). Conclusions In this study, a novel AI from B. coagulans NL01was cloned, purified and characterized. Compared with other reported AIs, this AI could retain high proportions of activity at a broader range of temperatures and was less dependent on metallic cofactors such as Mn2+. Its substrate specificity was understood deeply by carrying out molecular modelling and docking studies. When the recombinant E. coli expressing the AI was used as a biocatalyst, D-tagatose could be produced efficiently in a simple one-pot biotransformation system. Electronic supplementary material The online version of this article (doi:10.1186/s12896-016-0286-5) contains supplementary material, which is available to authorized users.

Alkalized cocoa powder (10-12%) (Shokinag cocoa, Germany), deodrised cocoa butter (KLK-Kepong, Malysia), Inulin GR (Orafti, Belgium), D-tagatose (Damhert,Belgium), Sucrose (Karoon Co., Iran), Soy Lecithin (Cargill, Netherland), Stevia (Stevian Biotechnology Co., Malysia) and vanilla powder (Panda, China) were used for the production of dark chocolates .Experimental samples were produced by mixing Sucrose, D-tagatose and Inulin powders(51.4%),cocoa powder(16%), cocoa butter (32%), lecithin(0.5%) and vanillin (0.1%). Since Inulin and D-tagatose are less sweet than the sucrose the samples were additionally sweetened with stevia. Concentration of stevia was adjusted from the

The efficient isomerization of l-rhamnose [the only cheaply available deoxy hexose] to 1-deoxy-l-psicose, 1-deoxy-d-psicose, 1-deoxy-l-fructose, 1-deoxy-d-fructose, 1-deoxy-l-tagatose, 6-deoxy-l-psicose, 6-deoxy-d-psicose, 6-deoxy-l-fructose, 6-deoxy-d-fructose, and 6-deoxy-l-tagatose is described. The conversion of rhamnose to ten of the sixteen 1- and 6-deoxyketohexoses is accomplished in water in three steps. The range of substrates for d-tagatose-3-epimerase (DTE) is extended to 1- and 6-deoxyketoses. An authentic sample of 6-deoxy-d-psicose is prepared from d-psicose. © 2009 Elsevier Ltd. All rights reserved.

Four novel disaccharides of glycosylated 1,5-anhydro-D-ketoses have been prepared: 1,5-anhydro-4-O-beta-D-glucopyranosyl-D-fructose, 1,5-anhydro-4-O-beta-D-galactopyranosyl-D-fructose, 1,5-anhydro-4-O-beta-D-glucopyranosyl-D-tagatose, and 1,5-anhydro-4-O-beta-D-galactopyranosyl-D-tagatose. The common intermediate, 1,5-anhydro-2,3-O-isopropylidene-beta-D-fructopyranose, was prepared from D-fructose and was converted into the D-tagatose derivative by oxidation followed by stereoselective reduction to the 4-epimer. The anhydroketoses thus prepared were glycosylated and deprotected to give the disaccharides.

Zemplen methanolysis or a three-step protocol comprising hydroxylaminolysis, de-O-acetylation and deoximination smoothly and efficiently convert the benzoylated 2-hydroxy- d -glycals of d -galactose, l -rhamnose and d -xylose into their configurationally related 1,5-anhydro-ketoses, thereby providing convenient access to the 1,5-anhydro forms of d -tagatose, l -rhamnulose and d -xylulose. Invariably obtained as amorphous solids, they are best characterized through their highly crystalline oximes.

Microbial oxidation of 2-C-methyl-d-ribitol and 2-C-methyl-d-arabinitol by Gluconobacter thailandicus NBRC 3254 produces 4-C-methyl-l-ribulose and 4-C-methyl-d-ribulose, respectively. Further, 4-C-methyl-l-ribulose and 4-C-methyl-d-ribulose were equilibrated by d-tagatose-3-epimerase (DTE) with 4-C-methyl-l-xylulose and 4-C-methyl-d-xylulose, respectively. These transformations demonstrate that polyol dehydrogenase and DTE act on branched synthetic sugars. The green preparation of all of the stereoisomers of 4-C-methyl pentuloses illustrates the ability of biotechnology to generate novel branched monosaccharides. © 2008 Elsevier Ltd. All rights reserved.

d-tagatose is produced from d-galactose by the enzyme l-arabinose isomerase (L-AI) in a commercially viable bioprocess. An active and stable biocatalyst was obtained by modifying chitosan gel structure through reaction with TNBS, d-fructose or DMF, among others. This led to a significant improvement in L-AI immobilization via multipoint covalent attachment approach. Synthetized derivatives were compared with commercial supports such as Eupergit® C250L and glyoxal-agarose. The best chitosan derivative for L-AI immobilization was achieved by reacting 4 % (w/v) d-fructose with 3 % (w/v) chitosan at 50 °C for 4 h. When compared to the free enzyme, the glutaraldehyde-activated chitosan biocatalyst showed an apparent activity of 88.4 U ggel −1 with a 211-fold stabilization factor while the glyoxal-agarose biocatalyst gave an apparent activity of 161.8 U ggel −1 with an 85-fold stabilization factor. Hence, chitosan derivatives were comparable to commercial resins, thus becoming a viable low-cost strategy to obtain high active L-AI insolubilized derivatives.d-tagatose is produced from d-galactose by the enzyme l-arabinose isomerase (L-AI) in a commercially viable bioprocess. An active and stable biocatalyst was obtained by modifying chitosan gel structure through reaction with TNBS, d-fructose or DMF, among others. This led to a significant improvement in L-AI immobilization via multipoint covalent attachment approach. Synthetized derivatives were compared with commercial supports such as Eupergit® C250L and glyoxal-agarose. The best chitosan derivative for L-AI immobilization was achieved by reacting 4 % (w/v) d-fructose with 3 % (w/v) chitosan at 50 °C for 4 h. When compared to the free enzyme, the glutaraldehyde-activated chitosan biocatalyst showed an apparent activity of 88.4 U ggel −1 with a 211-fold stabilization factor while the glyoxal-agarose biocatalyst gave an apparent activity of 161.8 U ggel −1 with an 85-fold stabilization factor. Hence, chitosan derivatives were comparable to commercial resins, thus becoming a viable low-cost strategy to obtain high active L-AI insolubilized derivatives. Fil: Manzo, Ricardo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: de Sousa, Marylane. Universidade Estadual do Ceará; Brasil Fil: Fenoglio, Cecilia Lorena. Universidad Nacional del Litoral; Argentina Fil: Gonçalves, Luciana Rocha Barro. Universidade Estadual do Ceará; Brasil Fil: Mammarella, Enrique José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

1,4-Anhydro-D-fructose and 1,4-anhydro-D-tagatose were prepared from 1,2-O-isopropylidene-D-glucofuranose via the common intermediate 3,5,6-tri-O-benzyl-D-glucitol. The title compounds may be interesting anti-oxidants and feature activities akin to their natural pyranoid counterpart, 1,5-anhydro-D-fructose.

N‐Acetyl‐d‐galactosamine (11), a very important naturally occurring building block of oligosaccharides, is easily accessible via the Heyns rearrangement of d‐tagatose (3) with benzylamine. The short and efficient synthesis of various differently N‐protected d‐galactosamine derivatives is reported.

The L-arabinose isomerase (L-AI) and the D-xylose isomerase (D-XI) encoding genes from Lactobacillus reuteri (DSMZ 17509) were cloned and overexpressed in Escherichia coli BL21 (DE3). The proteins were purified to homogeneity by one-step affinity chromatography and characterized biochemically. L-AI displayed maximum activity at 65 °C and pH 6.0, whereas D-XI showed maximum activity at 65 °C and pH 5.0. Both enzymes require divalent metal ions. The genes were also ligated into the inducible lactobacillal expression vectors pSIP409 and pSIP609, the latter containing a food grade auxotrophy marker instead of an antibiotic resistance marker, and the L-AI- and D-XI-encoding sequences/genes were coexpressed in the food grade host Lactobacillus plantarum . The recombinant enzymes were tested for applications in carbohydrate conversion reactions of industrial relevance. The purified L-AI converted D-galactose to D-tagatose with a maximum conversion rate of 35%, and the D-XI isomerized D-glucose to D-fructose with a maximum conversion rate of 48% at 60 °C.

Synopsis Most toothpastes contain either d-sorbitol or glycerin, or both, as humectants. Both compounds are about half as sweet as sucrose. This level of sweetness is not as intense as desired by most people when brushing teeth. Therefore, many brands of toothpaste add saccharin, a high-intensity sweetener, to increase product sweetness to acceptable levels. While this combination provides the required bulk, humectancy and sweetness, the last characteristic suffers from the widely perceived metallic, or bitter, aftertaste of saccharin. d-tagatose, a full-bulk, low-calorie, sucrose-like sweetener with about twice the sweetness of d-sorbitol, and which does not promote tooth decay, holds promise as a sole sweetener for toothpastes. The only untested aspect of this use of d-tagatose was its humectancy, the characteristic that retains the required level of moisture in toothpaste. The current study was made to investigate this important property, to make a direct comparison of the humectancies of d-tagatose and d-sorbitol as pure substances, and to determine whether the humectancy of d-tagatose is sufficient to counter the crystallizing potentiation of the abrasives used in toothpastes. The humectancies of d-tagatose and d-sorbitol were tested through measuring their water activity (aw) vs. water content. By comparing their desorption curves, d-tagatose was seen to have a humectancy equal to that of d-sorbitol when aw in the d-tagatose solution was above 0.62. d-Tagatose was then tested in toothpastes containing typical abrasives to determine whether the abrasives would induce crystallization of the sweetener. The addition of 20–25% wt/wt of d-tagatose to the Tom of Maine's toothpastes imparted a satisfactory sweetness. It was found that, within that range of concentration, d-tagatose retained its humectancy, and did not crystallize in the popular brands of commercial toothpastes tested. Thus, d-tagatose could be used as a humectant sweetener in toothpastes, although further work on a final toothpaste formula will be necessary to check stability and flavour factors. Resume La plupart des dentifrices contiennent soit du D-sorbitol soit de la glycerine, ou les deux, comme humidifiants. Ces deux composes sont environs deux fois moins sucres que le sucrose. Ce niveau de douceur n'est pas aussi eleve que celui souhaite par la plupart des gens lorsqu'ils se brossent les dents. Par consequent, de nombreuses marques de dentifrice ajoutent de la saccharine, un edulcorant de grande intensite, pour ameliorer la douceur du produit jusqu'a des niveaux acceptables. Bien que cette association donne la consistance, le pouvoir mouillant et la douceur attendus, cette derniere caracteristique souffre de l'arriere gout metallique ou amer de la saccharine, largement percu. Le D-tagatose, edulcorant en vrac de type sucrose, basse calories ayant environ deux fois la douceur du D-sorbitol, et qui ne favorise pas l'attaque des dents, promet d'etre un edulcorant unique pour les dentifrices. Le seul aspect non teste de cet usage du D-tagatose etait son pouvoir d'humidification, la propriete qui maintient la teneur requise en hydratation dans le dentifrice. La presente etude a ete menve pour etudier cette propriete importante, afin de faire une comparaison directe des pouvoirs d'humidification du D-tagatose et du D-sorbitol comme substances pures, et de determiner si la capacite d'humidification du D-tagatose est suffisante pour compenser le pouvoir de cristallisation des abrasifs utilises dans les dentifrices. Les capacites d'humidification du D-tagatose et du D-sorbitol ont ete testees par la mesure de leur activite en eau (aw) en fonction de leur teneur en eau. Apres comparaison de leurs courbes de desorption, le D-tagatose revele une capacite d'humidification egale a celle du D-sorbitol lorsque aw dans la solution de D-tagatose est superieur a 0.62. Le D-tagatose a ensuite ete teste dans des dentifrices contenant des abrasifs classiques pour determiner si les abrasifs conduisent a une cristallisation de l'edulcorant. L'ajout de 20-25 % en poids de D-tagatose aux dentifrices ‘Tom of Maine’ confere une douceur satisfaisante. On observe que, dans cet intervalle de concentration, le D-tagatose conserve sa capacite d'humidification, et ne cristallise pas dans les marques courantes de dentifrices commerciaux testes. Ainsi, le D-tagatose peut elise comme edulcorant humidificateur dans les dentifrices, bien que des travaux supplementaires sur la formule finale du dentifrice soient necessaires pour verifier la stabilite et les facteurs d'aromes.

1,2 -O- Isopropylidene-β- d -fructopyranose was directly converted into 5 -O- cyclohexylcarbamoyl-1,2 -O- isopropylidene-3,4 -O- (2,2,2-trichloroethylidene)-β- d -tagatopyranose by treatment with chloral/ N , N ′-dicyclohexylcarbodiimide. Subsequent acid-catalysed cleavage of the isopropylidene protecting group followed by acetylation afforded, exclusively, 1,2-di -O- acetyl-5 -O- cyclohexylcarbamoyl-3,4 -O- (2,2,2-trichloroethylidene)-α- d -tagatopyranose. This product was simultaneously dehydrochlorinated and decarbamoylated to 1,2-di -O- acetyl-3,4 -O- ethylidene-α- d -tagatopyranose using Bu 3 SnH/AIBN.