Corrigendum: Probiotics: mechanism of action, health benefits and their application in food industries.

[This corrects the article DOI: 10.3389/fmicb.2023.1216674.].

A comprehensive review of recent advances in the characterization of L-rhamnose isomerase for the biocatalytic production of D-allose from D-allulose.

D-Allose and D-allulose are two important rare natural monosaccharides found in meager amounts. They are considered to be the ideal substitutes for table sugar (sucrose) for, their significantly lower calorie content with around 80 % and 70 % of the sweetness of sucrose, respectively. Additionally, both monosaccharides have gained much attention due to their remarkable physiological properties and excellent health benefits. Nevertheless, D-allose and D-allulose are rare in nature and difficult to produce by chemical methods. Consequently, scientists are exploring bioconversion methods to convert D-allulose into D-allose, with a key enzyme, L-rhamnose isomerase (L-RhIse), playing a remarkable role in this process. This review provides an in-depth analysis of the extractions, physiological functions and applications of D-allose from D-allulose. Specifically, it provides a detailed description of all documented L-RhIse, encompassing their biochemical properties including, pH, temperature, stabilities, half-lives, metal ion dependence, molecular weight, kinetic parameters, specific activities and specificities of the substrates, conversion ratio, crystal structure, catalytic mechanism as well as their wide-ranging applications across diverse fields. So far, L-RhIses have been discovered and characterized experimentally by numerous mesophilic and thermophilic bacteria. Furthermore, the crystal forms of L-RhIses from E. coli and Stutzerimonas/Pseudomonas stutzeri have been previously cracked, together with their catalytic mechanism. However, there is room for further exploration, particularly the molecular modification of L-RhIse for enhancing its catalytic performance and thermostability through the directed evolution or site-directed mutagenesis.

Probiotics: mechanism of action, health benefits and their application in food industries.

Probiotics, like lactic acid bacteria, are non-pathogenic microbes that exert health benefits to the host when administered in adequate quantity. Currently, research is being conducted on the molecular events and applications of probiotics. The suggested mechanisms by which probiotics exert their action include; competitive exclusion of pathogens for adhesion sites, improvement of the intestinal mucosal barrier, gut immunomodulation, and neurotransmitter synthesis. This review emphasizes the recent advances in the health benefits of probiotics and the emerging applications of probiotics in the food industry. Due to their capability to modulate gut microbiota and attenuate the immune system, probiotics could be used as an adjuvant in hypertension, hypercholesterolemia, cancer, and gastrointestinal diseases. Considering the functional properties, probiotics are being used in the dairy, beverage, and baking industries. After developing the latest techniques by researchers, probiotics can now survive within harsh processing conditions and withstand GI stresses quite effectively. Thus, the potential of probiotics can efficiently be utilized on a commercial scale in food processing industries.

Fabrication and Characterization of Apple-Pectin-PVA-Based Nanofibers for Improved Viability of Probiotics.

In the current study, apple-pectin-based novel nanofibers were fabricated by electrospinning. Polyvinyl alcohol (PVA) and apple pectin (PEC) solution were mixed to obtain an optimized ratio for the preparation of electrospun nanofibers. The obtained nanofibers were characterized for their physiochemical, mechanical and thermal properties. The nanofibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). Furthermore, an assay of the in vitro viability of free and encapsulated probiotics was carried out under simulated gastrointestinal conditions. The results of TGA revealed that the PVA/PEC nanofibers had good thermal stability. The probiotics encapsulated by electrospinning showed a high survival rate as compared to free cells under simulated gastrointestinal conditions. Furthermore, encapsulated probiotics and free cells showed a 3 log (cfu/mL) and 10 log (cfu/mL) reduction, respectively, from 30 to 120 min of simulated digestion. These findings indicate that the PVA/PEC-based nanofibers have good barrier properties and could potentially be used for the improved viability of probiotics under simulated gastrointestinal conditions and in the development of functional foods.

Recent progress in CRISPR-based bioengineering of microbial cell factories for important nutraceuticals synthesis.

Nutraceuticals are defined as food or food components with therapeutic capabilities that have few side effects and are regarded as a natural therapy for preventing the onset of several life-threatening illnesses. The use of microbial cell factories to produce nutraceuticals is considered to be sustainable and promising for meeting market demand. Among the diverse strategies for optimizing microbial cell factories, the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) system has emerged as a valuable tool for gene integration, deletion, activation, and downregulation. With the advent of multiplexed and precise CRISPR strategies, optimized microbial cell factories are revolutionizing the yield of nutraceuticals. This review focuses on the development of highly adaptable CRISPR strategies to optimize the production in microbial cell factories of some important nutraceuticals (belonging to the class of carotenoids, flavonoids, stilbenoids, polysaccharides, and nonprotein amino acids). Further, we highlighted current challenges related to the efficiency of CRISPR strategies and addressed potential future directions to fully harness CRISPR strategies to make nutraceutical synthesis in microbial cell factories an industrially favorable method.

High-intensity ultrasonication impact on the chlorothalonil fungicide and its reduction pathway in spinach juice.

Among different novel technologies, sonochemistry is a sustainable emerging technology for food processing, preservation, and pesticide removal. The study aimed to probe the impact of high-intensity ultrasonication on chlorothalonil fungicide degradation, reduction pathway, and bioactive availability of spinach juice. The chlorothalonil fungicide-immersed spinach juice was treated with sonication at 360 W, 480 W, and 600 W, 40 kHz, for 30 and 40 min at 30 ± 1 °C. The highest reduction of chlorothalonil fungicide residues was observed at 40 min sonication at 600 W. HPLC-MS (high-performance liquid chromatography-mass spectroscopy) analysis revealed the degradation pathway of chlorothalonil and the formation of m-phthalonitrile, 3-cyno-2,4,5,6-tetrachlorobenamide, 4-dichloroisophthalonitrile, trichloroisophtalonitrile, 4-hydoxychlorothalonil, and 2,3,4,6-tetrachlorochlorobenzonitrile as degradation products. High-intensity sonication treatments also significantly increased the bioavailability of phenolic, chlorophyll, and anthocyanins and the antioxidant activity of spinach juice. Our results proposed that sonication technology has excellent potential in degrading pesticides through free radical reactions formation and pyrolysis. Considering future perspectives, ultrasonication could be employed industrially to reduce pesticide residues from agricultural products and enhance the quality of spinach juice.

Bacterial metabolic engineering for the production of second-generation (2 G) bioethanol and biobutanol; a review.

The second generation (2 G) biofuels were introduced to solve the issues associated with first-generation biofuel (dependency on food materials) and fossil fuels, such as reservoirs diminution, high demand, price fluctuation, and lethal greenhouse gases emission. Butanol and ethanol are the main 2 G biofuels. They are used as a disinfectant, antiseptic, and chemical solvent in the pharmaceutical, plastic, textiles, cosmetics, and fuel industries. Currently, their bacterial biological production from lignocellulosic material at the industrial level with primitive microorganisms is under development and not economical and qualitative compatible as compared to that of fossil origin, due to the slow growth rate, low titer, recalcitrant nature of lignocellulose, strain intolerance to a higher amount of butanol and ethanol, and strain inability to tolerate inhibitors accumulated during pretreatment of lignocellulosic materials. Therefore, metabolic engineering strategies such as redirection of carbon flux, knocking out competing pathways, enhancing strain robustness and wide range of substrate utilization ability, and overexpression of enzymes involved in their biological synthesis have been applied to bacteria for enhancing their ability for 2 G ethanol and butanol production in a highly cost-effective amount from lignocellulosic materials. Herein, we summarized and reviewed the progress in metabolic engineering of bacterial species such as Clostridium spp,Escherichia coli, and Zymomonas mobilis for the synthesis of 2 G butanol and ethanol, especially from lignocellulosic materials.

Characterization of l-fucose isomerase from Paenibacillus rhizosphaerae to produce l-fuculose from hydrolyzed fucoidan and commercial fucose.

AIMS: l-Fuculose is a valuable rare sugar that is used to treat a variety of ailments, including HIV, cancer, Hepatitis B, human lysosomal disease (fucosidosis), and cardio-protective medications. The enzymatic approach for the production of l-fuculose using l-fucose as a substrate would be an advantageous method with a wide range of industrial applications. The objective of this study is the characterization of recombinant l-fucose isomerase from Paenibacillus rhizosphaerae (Pa-LFI) for the production of l-fuculose from an inexpensive and natural source (fucoidan) as well as its comparison with commercial l-fucose (Sigma-Aldrich). METHODS AND RESULTS: Fucoidan, a fucose-containing polysaccharide (FPs), was isolated from Undaria pinnatifida, subsequently hydrolyzed, and characterized before the enzymatic production of l-fuculose. The results elaborate that FPs contain 35.9% of fucose along with other kinds of monosaccharides. The purified Pa-LFI exhibited a single band at 65 kDa and showed it as a hexamer with a native molecular mass of 396 kDa. The highest activity of 104.5 U mg-1 of Pa-LFI was perceived at a temperature of 50°C and pH 6.5 in the presence of 1 mM of Mn2+. The Pa-LFI revealed a melting temperature (Tm) of 75°C and a half-life of 12.6 h at 50°C. It exhibited that Pa-LFI with aldose substrate (l-fucose), has a stronger isomerizing activity, disclosing Km,kcat, and kcat/Km 86.2 mM, 32 831 min-1, and 335 min-1 mM-1, respectively. After reaching equilibrium, Pa-LFI efficiently catalyzed the reaction to convert l-fucose into l-fuculose and the conversion ratios of l-fuculose from 100 g L-1 of FPs and commercial fucose were around 6% (5.6 g L-1) and 30% (30.2 g L-1), respectively. CONCLUSIONS: According to the findings of the current study, the Pa-LFI will be useful in the manufacturing of l-fuculose using an effective and easy approach that produces no by-products.

Cottonseed oil: A review of extraction techniques, physicochemical, functional, and nutritional properties.

Seed oils are the richest source of vitamin-E-active compounds, which contribute significantly to antioxidant activities. Cottonseed oil (CS-O) is attaining more consideration owing to its high fiber content and stability against auto-oxidation. CS-O has gained a good reputation in the global edible oil market due to its distinctive fatty acid profile, anti-inflammatory, and cardio-protective properties. CS-O can be extracted from cottonseed (CS) by microwave-assisted extraction (MAE), aqueous/solvent extraction (A/SE), aqueous ethanol extraction (A-EE), subcritical water extraction, supercritical carbon dioxide extraction (SC-CO2), and enzyme-assisted extraction (E-AE). In this review, the importance, byproducts, physicochemical characteristics, and nutritional profile of CS-O have been explained in detail. This paper also provides a summary of scientific studies existing on functional and phytochemical characteristics of CS-O. Its consumption and health benefits are also deliberated to discover its profitability and applications. CS-O contains 26-35% saturated, 42-52% polyunsaturated, and 18-24% monounsaturated FA. There is approximately 1000 ppm of tocopherols in unprocessed CS-O, but up to one-third is lost during processing. Moreover, besides being consumed as cooking oil, CS-O discovers applications in many fields such as biofuel, livestock, cosmetics, agriculture, and chemicals. This paper provides a comprehensive review of CS-O, its positive benefits, fatty acid profile, extraction techniques, and health applications.HighlightsCS-O is a rich source of exceptional fatty acids.Various techniques to extract the CS-O are discussed.Numerous physicochemical properties of CS-O for the potential market are assessed.It has a wide range of functional properties.Nutritional quality and health benefits are also evaluated.

Influence of baking and frying conditions on acrylamide formation in various prepared bakery, snack, and fried products.

The core objective of the present study was to evaluate the influence of baking/frying times and temperatures on the formation of acrylamide in bakery, snack, and fried products such as biscuits, muffins, pizza, cakes, samosa, paratha rolls, nuggets, and potato cutlets during baking/frying at different times and temperature conditions. First of all, the raw material, especially flour, was tested for its proximate composition and rheological characteristics. The quantification of acrylamide produced during the processing of different products was carried out through the HPLC method. A sensory evaluation of these food samples was also carried out to find out the acceptability differences. The raw material was found to have good rheological properties and proximate composition. The results revealed that different times and temperature regimes influenced the formation of acrylamide in those products. Among the bakery products, the highest concentrations of acrylamide were observed in biscuits (126.52 µg/kg) followed by muffins (84.24 µg/kg), cake (71.21 µg/kg), and pizza (62.42 µg/kg). The higher contents of acrylamide were found in paratha roll (165.92 µg/kg) compared to samosa (100.43 µg/kg), whereas among snacks, potato cutlets (135.71 µg/kg) showed higher concentrations than nuggets (43.04 µg/kg). It was observed that baking or frying all the investigated products at higher temperatures produced slightly more acrylamide concentrations. The prepared products in the present study were also accepted sensorially by the panel of judges. So, it was concluded that baking or frying at higher temperatures resulted in higher concentrations of acrylamide compounds in different products in the present study.

Fucoidan-based nanomaterial and its multifunctional role for pharmaceutical and biomedical applications.

Fucoidans are promising sulfated polysaccharides isolated from marine sources that have piqued the interest of scientists in recent years due to their widespread use as a bioactive substance. Bioactive coatings and films, unsurprisingly, have seized these substances to create novel, culinary, therapeutic, and diagnostic bioactive nanomaterials. The applications of fucoidan and its composite nanomaterials have a wide variety of food as well as pharmacological properties, including anti-oxidative, anti-inflammatory, anti-cancer, anti-thrombic, anti-coagulant, immunoregulatory, and anti-viral properties. Blends of fucoidan with other biopolymers such as chitosan, alginate, curdlan, starch, etc., have shown promising coating and film-forming capabilities. A blending of biopolymers is a recommended approach to improve their anticipated properties. This review focuses on the fundamental knowledge and current development of fucoidan, fucoidan-based composite material for bioactive coatings and films, and their biological properties. In this article, fucoidan-based edible bioactive coatings and films expressed excellent mechanical strength that can prolong the shelf-life of food products and maintain their biodegradability. Additionally, these coatings and films showed numerous applications in the biomedical field and contribute to the economy. We hope this review can deliver the theoretical basis for the development of fucoidan-based bioactive material and films.

The Characterization of a Novel D-allulose 3-Epimerase from Blautia produca and Its Application in D-allulose Production.

D-allulose is a natural rare sugar with important physiological properties that is used in food, health care items, and even the pharmaceutical industry. In the current study, a novel D-allulose 3-epimerase gene (Bp-DAE) from the probiotic strain Blautia produca was discovered for the production and characterization of an enzyme known as Bp-DAE that can epimerize D-fructose into D-allulose. Bp-DAE was strictly dependent on metals (Mn2+ and Co2+), and the addition of 1 mM of Mn2+ could enhance the half-life of Bp-DAE at 55 °C from 60 to 180 min. It exhibited optimal activity in a pH of 8 and 55 °C, and the Km values of Bp-DAE for the different substrates D-fructose and D-allulose were 235.7 and 150.7 mM, respectively. Bp-DAE was used for the transformation from 500 g/L D-fructose to 150 g/L D-allulose and exhibited a 30% of conversion yield during biotransformation. Furthermore, it was possible to employ the food-grade microbial species Bacillus subtilis for the production of D-allulose using a technique of whole-cell catalysis to circumvent the laborious process of enzyme purification and to obtain a more stable biocatalyst. This method also yields a 30% conversion yield.

A review of the enzymatic, physical, and chemical modification techniques of xanthan gum.

Xanthan gum (XG), a bacterial polysaccharide has numerous valuable characteristics in the food, biomedical, pharmaceuticals, and agriculture sector. However, XG has also its particular limitations such as its vulnerability to microbial contamination, inadequate mechanical and thermal stability, unusable viscosity, and poor water solubility. Therefore, XG's structure and conformation need to be modified enzymatically, chemically, or physically to improve its optimistic features and decrease the formation of crystals, increase antioxidant ability, and radical scavenging activity. We have found out different means to modify XG and elaborate the importance and significance of the modified structure of XG. In this review, different enzymes are reviewed for XG degradation, which modifies their structure from different points (main chain or side chain). This article also reviews various physical methods (ultrasound, shear, pressure, sonication, annealing, and heat treatments) based on prevailing publications to alter XG conformation and produce low molecular weight (LMW) and less viscous end-product. Moreover, some chemical means are also discussed that result in modified XG through crosslinking, grafting, acetylation, pyruvation, as well as by applying different chemical agents. Overall, the current progress on XG degradation is very auspicious to develop a new molecule with considerable uses, in various industries with future assessments.

A review on l-ribose isomerases for the biocatalytic production of l-ribose and l-ribulose.

Presently, because of the extraordinary roles and potential applications, rare sugars turn into a focus point for countless researchers in the field of carbohydrates. l-ribose and l-ribulose are rare sugars and isomers of each other. This aldo and ketopentose are expensive but can be utilized as an antecedent for the manufacturing of various rare sugars and l-nucleoside analogue. The bioconversion approach turns into an excellent alternative method to l-ribulose and l-ribose production, as compared to the complex and lengthy chemical methods. The basic purpose of this research was to describe the importance of rare sugars in various fields and their easy production by using enzymatic methods. l-Ribose isomerase (L-RI) is an enzyme discovered by Tsuyoshi Shimonishi and Ken Izumori in 1996 from Acinetobacter sp. strain DL-28. L-RI structure was cupin-type-ß-barrel shaped with a catalytic site between two ß-sheets surrounded by metal ions. The crystal structures of the L-RI showed that it contains a homotetramer structure. Current review have concentrated on the sources, characteristics, applications, conclusions and future prospects including the potentials of l-ribose isomerase for the commercial production of l-ribose and l-ribulose. The MmL-RIse and CrL-RIse have the potential to produce the l-ribulose up to 32% and 31%, respectively. The CrL-RIse is highly stable as compared to other L-RIs. The results explained that the L-RIs have great potential in the production of rare sugars especially, l-ribose and l-ribulose, while the immobilization technique can enhance its functionality and properties. The present study precises the applications of L-RIs acquired from various sources for l-ribose and l-ribulose production.

A review on selective l-fucose/d-arabinose isomerases for biocatalytic production of l-fuculose/d-ribulose.

L-Fuculose and D-ribulose are kinds of rare sugars used in food, agriculture, and medicine industries. These are pentoses and categorized into the two main groups, aldo pentoses and ketopentoses. There are 8 aldo- and 4 ketopentoses and only fewer are natural, while others are rare sugars found in a very small amount in nature. These sugars have great commercial applications, especially in many kinds of drugs in the medicine industry. The synthesis of these sugars is very expensive, difficult by chemical methods due to its absence in nature, and could not meet industry demands. The pentose izumoring strategy offers a complete enzymatic tactic to link all kinds of pentoses using different enzymes. The enzymatic production of L-fuculose and D-ribulose through L-fucose isomerase (L-FI) and D-arabinose isomerase (D-AI) is the inexpensive and uncomplicated method up till now. Both enzymes have similar kinds of isomerizing mechanisms and each enzyme can catalyze both L-fucose and D-arabinose. In this review article, the enzymatic process of biochemically characterized L-FI & D-AI, their application to produce L-fuculose and D-ribulose and its uses in food, agriculture, and medicine industries are reviewed.

Ethanolic extract of okra has a potential gastroprotective effect on acute gastric lesions in Sprague Dawley rats.

Okra (Abelmoschus esculentus) has various bioactive components used for the treatment of different diseases such as gastritis and ulcers. This research aims to examine the anti-inflammatory and anti-ulcer attributes of okra extract against gastric lesions. Adult Sprague Dawley male albino rats were divided into five groups. The negative control (G1) received normal feed, positive control (G2) received ulcer-inducing drug aspirin 150 mg/kg of body weight (b.w), G3 group received reference drug omeprazole 20 mg/kg of b.w, G4 group received okra extract 250 mg/kg of b.w, and G5 group received 500 mg/kg of b.w. Acute gastric damage was induced in G1, G2, G3, and G4 using aspirin 150 mg/kg of b.w, during 14-day-long efficacy trials after that all the animals were sacrificed. Anti-ulcer parameters and histopathological analysis of stomachs were performed to evaluate the degree of recovery against tissue damage by the administration of okra extract. The obtained results indicated that the 500 mg/kg of b.w okra extract exerted a protective effect in aspirin-induced gastric ulcers by significantly (p < .05) reducing ulcer score, ulcer area, total acidity, and gastric volume, and significantly (p < .05) increasing gastric pH. Moreover, histopathological observation revealed that gastric mucosa was normal in G1, G3, G4, and G5; however, disruptions in the gastric epithelium were observed in G2. Congestion was observed in all groups except G1 and G5. Gastric pits and gastric glands were increased in size in G2 and G4. A higher concentration of okra extract (500 mg/kg of b.w) showed almost similar results when compared to the reference drug omeprazole.

Role of peppermint oil in improving the oxidative stability and antioxidant capacity of borage seed oil-loaded nanoemulsions fabricated by modified starch.

Borage seed oil (BSO) is one of the richest sources of γ-linolenic acid and linoleic acid, which are considered to retain plenty of health promoting benefits. However, its application in functional foods and dietary supplements remains limited owing to its superior vulnerability to oxidation. To solve this problem, ultrasound-assisted BSO-loaded nanoemulsions were prepared with modified starch incorporating different concentrations of peppermint oil (PO), as a natural antioxidant. The influence of different PO levels on the mean droplet size, rheology attributes, and oxidative stability of nanoemulsions stored at various temperatures (4, 25, and 40 °C) during 30 days storage was analyzed. In addition, DPPH and ABTS assays were used to determine the antioxidant activity and antioxidant capacity of BSO-loaded nanoemulsions, respectively. The optimized formulation (NE3; 5:5% v/v PO: BSO) exhibited a slight change in droplet size and oxidative stability at all temperatures during storage compared to other formulations. At a concentration of 328.08 µL/mL, formulation NE3 presented the minimum DPPH IC50 at 40 °C, which was lower than other formulations. The findings of this study revealed that the maximum retained antioxidant capacity (99.42 µg Trolox/mL) was related to NE3 comprising (5:5% v/v PO: BSO) stored at 40 °C for 30 days; which could be accredited to the role of PO as a natural antioxidant in order to improve the oxidative stability of nanoemulsion delivery system. Taken together, co-encapsulation of BSO and PO within nanoemulsions provides novel insights regarding the development of functional foods, dietary supplements and beverages.

Characterization of a recombinant l-ribose isomerase from Mycetocola miduiensis and its application for the production of l-ribulose.

An enzyme, l-ribose isomerase (l-RI), mostly catalyzes the isomerization of l-ribose and l-ribulose. These so-called rare sugars are essential for the treatment of cancer and other viral diseases. In the present study, l-ribose isomerase produced from a bacterium, Mycetocola miduiensis (Mm-LRIse), by using l-ribose as a carbon source. The recombinant l-ribose isomerase gene was cloned and overexpressed from M. miduiensis and purified with an exclusive band of 32 kDa by nickel-affinity chromatography. This gene possessed 267 amino acids protein having an estimated molecular weight of 29,568.17 Da. The native molecular weight of Mm-LRIse estimated by HPLC was 134.84 kDa. The recombinant l-ribose isomerase was highly active in sodium phosphate (50 mM) buffer at 40 °C and pH 7.5, showing the specific activity up to 47.40 U mg-1. Mm-LRIse showed no significant enhancement in activity with metallic ions except Mn2+ and Co2+. The values of Km, Kcat, Kcat/Km and Vmax of Mm-LRIse against l-ribose substrate were 42.48 mM, 9259.26 min-1, 217.43 min-1 mM-1, and 277.78 U mg-1 respectively. At equilibrium, the l-ribulose transformation rate was nearly 32 % (6.34 g L-1) using 20 g L-1 of l-ribose. The results revealed that the Mm-LRIse enzyme has a potential for L-ribulose production from l-ribose.

Characterization of a novel d-arabinose isomerase from Thermanaeromonas toyohensis and its application for the production of d-ribulose and l-fuculose.

d-Ribulose and l-fuculose are potentially valuable rare sugars useful for anticancer and antiviral drugs in the agriculture and medicine industries. These rare sugars are usually produced by chemical methods, which are generally expensive, complicated and do not meet the increasing demands. Furthermore, the isomerization of d-arabinose and l-fucose byDd-arabinose and l-fucose by d-arabinose isomerase from bacterial sources for the production of d-ribulose and l-fuculose have not yet become industrial due to the shortage of biocatalysts, resulting in poor yield and high cost of production. In this study, a thermostable d-ribulose- and l-fuculose producing d-arabinose isomerase from the bacterium Thermanaeromonas toyohensis was characterized. The recombinant d-arabinose isomerase from T. toyohensis (Thto-DaIase) was purified with a single band at 66 kDa using His-trap affinity chromatography. The native enzyme existed as a homotetramer with a molecular weight of 310 kDa, and the specific activities for both d-arabinose and l-fucose were observed to be 98.08 and 85.52 U mg-1, respectively. The thermostable recombinant Thto-DaIase was activated when 1 mM Mn2+ was added to the reactions at an optimum pH of 9.0 at 75 °C and showed approximately 50% activity for both d-arabinose and l-fucose at 75 °C after 10 h. The Michaelis-Menten constant (Km), the turnover number (kcat) and catalytic efficiency (kcat/Km) for d-arabinose/l-fucose were 111/81.24 mM, 18,466/10,688 min-1, and 166/132 mM-1  min-1, respectively. When the reaction reached to equilibrium, the conversion rates of d-ribulose from d-arabinose and l-fuculose from l-fucose were almost 27% (21 g L-1) and 24.88% (19.92 g L-1) from 80 g L-1 of d-arabinose and l-fucose, respectively.

Aptamer Induced Multicolored AuNCs-WS2 "Turn on" FRET Nano Platform for Dual-Color Simultaneous Detection of AflatoxinB1 and Zearalenone.

Mycotoxins posit serious threats to human and animal health, and numerous efforts have been performed to detect the multiple toxins by a single diagnostic approach. To best of our knowledge, for the first time, we synthesized an aptamer induced "turn on" fluorescence resonance energy transfer (FRET) biosensor using dual-color gold nanoclusters (AuNCs), l-proline, and BSA synthesized AuNCs (Lp-AuNCs and BSA-AuNCs), with WS2 nanosheet for simultaneous recognition of aflatoxinB1 (AFB1) and zearalenone (ZEN) by single excitation. Here, AFB1 aptamer stabilized blue-emitting AuNCs (AFB1-apt-Lp-AuNCs) (at 442 nm) and ZEN aptamer functionalized with red-colored AuNCs (ZEN-apt-BSA-AuNCs) (at 650 nm) were employed as an energy donor and WS2 nanosheet as a fluorescence quencher. With the addition of AFB1 and ZEN, the change in fluorescence intensity (F.I) was recorded at 442 and 650 nm and can be used for simultaneous recognition with a detection limit of 0.34 pg mL-1 (R2 = 0.9931) and 0.53 pg mL-1 (R2 = 0.9934), respectively. Most importantly, the semiquantitative determination of AFB1 and ZEN can also be realized through photovisualization. The current approach paves a new way to develop sensitive, selective, and convenient metal nanocluster-based fluorescent "switch-on" probes with potential applications in multipurpose biosensing.