Technological Aspects of the Production of Fructo and Galacto-Oligosaccharides. Enzymatic Synthesis and Hydrolysis

A novel strategy with in vivo characterization, extraction, isolation and activity evaluation for discovery of absorbed anti-inflammatory oligosaccharides from Zhu-Ling decoction

Zhu-Ling decoction (ZLD), a classical traditional Chinese medicine (TCM) formula, is used for the treatment of chronic kidney diseases. However, the structure and activity of absorbed oligosaccharides (OSs) in ZLD are not clear. In this study, a novel strategy with in vivo characterization, extraction, isolation, activity evaluation was established and applied to identify absorbed anti-inflammatory OSs in ZLD. The results revealed that 30 OSs (22 reducing and 8 non-reducing OSs) and 11 OSs (7 reducing and 4 non-reducing OS) were characterized from ZLD in vitro and in vivo by using UPLC/Q-TOF-MS with PMP derivatization, respectively. Among them, a series of -1 → 3-β-D-Glcp-OSs were isolated and identified by HPLC-HILIC-UVD-ELSD, SPHPLC-HILIC-RID, monosaccharide composition, MS and 1D/2D-NMR spectroscopy, including laminaritriose, laminaritetraose, laminaripentaose, laminarihexaose, laminariheptaose, laminarioctaose and laminarinonaose. Moreover, the 4 non-reducing absorbed OSs were identified by comparison with reference standards, including sucrose, trehalose, raffinose and stachyose. Among them, laminaritriose, laminaritetraose and laminaripentaose significantly inhibited TNF-α and IL-6 levels in LPS-induced HK-2 cell and exerted significant anti-inflammatory effects via the NF-κB and Akt/mTOR signaling pathways. Together, our work provides a novel strategy for discovery of absorbed anti-inflammatory OSs and broadens new horizons for the discovery of in vivo pharmacodynamic substances in TCM formulas.

Production of prebiotic enriched maple syrup through enzymatic conversion of sucrose into fructo-oligosaccharides

Maple syrup, a popular natural sweetener has a high content of sucrose, whose consumption is linked to different health issues such as obesity and diabetes. Hence, within this paper, the conversion of sucrose to prebiotics (fructo-oligosaccharides, FOS) was proposed as a promising approach to obtaining a healthier, value-added product. Enzymatic conversion was optimized with respect to key experimental factors, and thereafter derived immobilized preparation of fructosyltransferase (FTase) from Pectinex® Ultra SP-L (FTase-epoxy Purolite, 255 IU/g support) was successfully utilized to produce novel functional product in ten consecutive reaction cycles. The product, obtained under optimal conditions (60 °C, 7.65 IU/mL, 12 h), resulted in 56.0% FOS, 16.7% sucrose, and 27.3% monosaccharides of total carbohydrates, leading to a 1.6-fold reduction in caloric content. The obtained products` prebiotic potential toward the probiotic strain Lactobacillus plantarum 299v was demonstrated. The changes in physico-chemical and sensorial characteristics were esteemed as negligible.

Non-carrier immobilization of yeast cells by genipin crosslinking for the synthesis of prebiotic galactooligosaccharides from plant-derived galactose

Galactooligosaccharides (GOS), as mimics of human milk oligosaccharides, are important prebiotics for modulating the ecological balance of intestinal microbiota. A novel carrier-free cell immobilization method was established using genipin to cross-link Kluyveromyces lactis CGMCC 2.1494, which produced β-galactosidase, an enzyme essential for GOS synthesis. The resulting immobilized cells were characterized as stable by thermogravimetric analysis and confirmed to be crosslinked through scanning electron microscopy analysis (SEM) and Fourier transform infrared spectroscopy (FTIR). The Km and Vmax values of β-galactosidase in immobilized cells towards o-nitrophenyl β-D-galactoside were determined to be 3.446 mM and 2210 μmol min-1 g-1, respectively. The enzyme in the immobilized showed higher thermal and organic solvent tolerance compared to that in free cells. The immobilized cells were subsequently employed for GOS synthesis using plant-derived galactose as the substrate. The synthetic reaction conditions were optimized through both single-factor experiments and response surface methodology, resulting in a high yield of 49.1 %. Moreover, the immobilized cells showed good reusability and could be reused for at least 20 batches of GOS synthesis, with the enzyme activity remaining above 70 % at 35 °C.

Mechanisms and Intervention of Prebiotic Foods in Musculoskeletal Health

The review focuses primarily on collating and analyzing the mechanistic research data that discusses the function of prebiotics to halt the frailty of musculoskeletal system. Musculoskeletal diseases (MSDs) are frequently reported to co-occur within their own categories of conditions, such as osteoarthritis, rheumatoid arthritis, gouty arthritis, and psoriatic arthritis owing to their overlapping pathogenesis. Consequently, the same drugs are often used to manage the complications of most types. A few recent studies have addressed the therapeutic functions of gut microbes toward those commonly shared MSD pathway targets. Improving microbial diversity and enriching their population in the gut would promote the regeneration and recovery of the musculoskeletal system. Prebiotics are usually nondigestible substrates that are selectively used or digested by the gut microbes conferring health promotion. The microbial fermentation of prebiotics generates numerous host-beneficial therapeutic molecules. This study inspects the presumptive functions of plant-derived prebiotics for the growth and restoration of intestinal microbiota and the consequent improvement of skeletal health. The review also highlights the discrete functions of prebiotics against inflammation, autoimmunity, infection, physiologic overloading mechanism, and aging-associated loss of metabolism in MSD.

The Role of Nondigestible Oligosaccharides in Alleviating Human Chronic Diseases by Regulating the Gut Microbiota: A Review

The gut has been a focus of chronic disease research. The gut microbiota produces metabolites that act as signaling molecules and substrates, closely influencing host health. Nondigestible oligosaccharides (NDOs), as a common dietary fiber, play an important role in regulating the structure and function of the gut microbiota. Their mechanism of action is mainly attributed to providing a carbon source as specific probiotics, producing related metabolites, and regulating the gut microbial community. However, due to the selective utilization of oligosaccharides, some factors, such as the type and structure of oligosaccharides, have different impacts on the composition of microbial populations and the production of metabolites in the colon ecosystem. This review systematically describes the key factors influencing the selective utilization of oligosaccharides by microorganisms and elaborates how oligosaccharides affect the host's immune system, inflammation levels, and energy metabolism by regulating microbial diversity and metabolic function, which in turn affects the onset and progress of chronic diseases, especially diabetes, obesity, depression, intestinal inflammatory diseases, and constipation. In this review, we re-examine the interaction mechanisms between the gut microbiota and its associated metabolites and diseases, and we explore new strategies for promoting human health and combating chronic diseases through dietary interventions.

Galactooligosaccharides: Synthesis, metabolism, bioactivities and food applications

Prebiotics are non-digestible ingredients that exert significant health-promoting effects on hosts. Galactooligosaccharides (GOS) have remarkable prebiotic effects and structural similarity to human milk oligosaccharides. They generally comprise two to eight sugar units, including galactose and glucose, which are synthesized from substrate lactose by microbial β-galactosidase. Enzyme sources from probiotics have received particular interest because of their safety and potential to synthesize specific structures that are particularly metabolized by intestinal probiotics. Owing to advancements in modern analytical techniques, many GOS structures have been identified, which vary in degree of polymerization, glycosidic linkage, and branch location. After intake, GOS adjust gut microbiota which produce short chain fatty acids, and exhibit excellent biological activities. They selectively stimulate the proliferation of probiotics, inhibit the growth and adhesion of pathogenic bacteria, alleviate gastrointestinal, neurological, metabolic and allergic diseases, modulate metabolites production, and adjust ion storage and absorption. Additionally, GOS are safe and stable, with high solubility and clean taste, and thus are widely used as food additives. GOS can improve the appearance, flavor, taste, texture, viscosity, rheological properties, shelf life, and health benefits of food products. This review systemically covers GOS synthesis, structure identifications, metabolism mechanisms, prebiotic bioactivities and wide applications, focusing on recent advances.

Research of saccharides and related biocomplexes: A review with recent techniques and applications

Saccharides and biocompounds as saccharide (sugar) complexes have various roles and biological functions in living organisms due to modifications via nucleophilic substitution, polymerization, and complex formation reactions. Mostly, mono-, di-, oligo-, and polysaccharides are stabilized to inactive glycosides, which are formed in metabolic pathways. Natural saccharides are important in food and environmental monitoring. Glycosides with various functionalities are significant in clinical and medical research. Saccharides are often studied with the chromatographic methods of hydrophilic interaction liquid chromatography and anion exchange chromatograpy, but also with capillary electrophoresis and mass spectrometry with their on-line coupling systems. Sample preparation is important in the identification of saccharide compounds. The cases discussed here focus on bioscience, clinical, and food applications.

β-Galactosidase: a traditional enzyme given multiple roles through protein engineering

β-Galactosidases are crucial carbohydrate-active enzymes that naturally catalyze the hydrolysis of galactoside bonds in oligo- and disaccharides. These enzymes are commonly used to degrade lactose and produce low-lactose and lactose-free dairy products that are beneficial for lactose-intolerant people. β-galactosidases exhibit transgalactosylation activity, and they have been employed in the synthesis of galactose-containing compounds such as galactooligosaccharides. However, most β-galactosidases have intrinsic limitations, such as low transglycosylation efficiency, significant product inhibition effects, weak thermal stability, and a narrow substrate spectrum, which greatly hinder their applications. Enzyme engineering offers a solution for optimizing their catalytic performance. The study of the enzyme's structure paves the way toward explaining catalytic mechanisms and increasing the efficiency of enzyme engineering. In this review, the structure features of β-galactosidases from different glycosyl hydrolase families and the catalytic mechanisms are summarized in detail to offer guidance for protein engineering. The properties and applications of β-galactosidases are discussed. Additionally, the latest progress in β-galactosidase engineering and the strategies employed are highlighted. Based on the combined analysis of structure information and catalytic mechanisms, the ultimate goal of this review is to furnish a thorough direction for β-galactosidases engineering and promote their application in the food and dairy industries.

Fructo-oligofructose ameliorates 2,4-dinitrofluorobenzene-induced atopic dermatitis-like skin lesions and psychiatric comorbidities in mice

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by pruritus and eczema lesions and psychiatric comorbidities. The gut-brain-skin axis plays a pivotal role during AD development, which might suggest a novel therapeutic strategy for AD. The present study aims to uncover the protective effects and underlying mechanisms of fructo-oligofructose (FOS), a type of prebiotic, on AD-like skin manifestations and comorbid anxiety and depression in AD mice.

RESULTS

Female Kunming mice were treated topically with 2,4-dinitrofluorobenzene (DNFB) to induce AD-like symptoms and FOS was administered daily for 14 days. The results showed that FOS could alleviate AD-like skin lesions markedly as evidenced by dramatic decreases in severity score, scratching bouts, the levels of immunoglobulin E (IgE) and T helper 1(Th1)/Th2-related cytokines, and the infiltration of inflammatory cells and mast cells to the dermal tissues. The comorbid anxiety and depressive-like behaviors, estimated by the forced swimming test (FST), the tail-suspension test (TST), the open-field test (OFT), and the zero maze test (ZMT) in AD mice, were significantly attenuated by FOS. Fructo-oligofructose significantly upregulated brain neurotransmitters levels of 5-hydroxytryptamine (5-HT) and dopamine (DA). Furthermore, FOS treatment increased the relative abundance of gut microbiota, such as Prevotella and Lactobacillus and the concentrations of short-chain fatty acids (SCFAs), especially acetate and iso-butyrate in the feces of AD mice. The correlation analysis indicated that the reshaped gut microbiome composition and enhanced SCFAs formation are associated with skin inflammation and behavioral alteration.

CONCLUSION

Collectively, these data identify FOS as a promising microbiota-targeted treatment for AD-like skin inflammation and comorbid anxiety and depressive-like behaviors. © 2023 Society of Chemical Industry.

Production and Bioconversion Efficiency of Enzyme Membrane Bioreactors in the Synthesis of Valuable Products

The demand for bioactive molecules with nutritional benefits and pharmaceutically important properties is increasing, leading researchers to develop modified production strategies with low-cost purification processes. Recent developments in bioreactor technology can aid in the production of valuable products. Enzyme membrane bioreactors (EMRs) are emerging as sustainable synthesis processes in various agro-food industries, biofuel applications, and waste management processes. EMRs are modified reactors used for chemical reactions and product separation, particularly large-molecule hydrolysis and the conversion of macromolecules. EMRs generally produce low-molecular-weight carbohydrates, such as oligosaccharides, fructooligosaccharides, and gentiooligosaccharides. In this review, we provide a comprehensive overview of the use of EMRs for the production of valuable products, such as oligosaccharides and oligodextrans, and we discuss their application in the bioconversion of inulin, lignin, and sugars. Furthermore, we critically summarize the application and limitations of EMRs. This review provides important insights that can aid in the production of valuable products by food and pharmaceutical industries, and it is intended to assist scientists in developing improved quality and environmentally friendly prebiotics using EMRs.

Chickpeas' and Lentils' Soaking and Cooking Wastewaters Repurposed for Growing Lactic Acid Bacteria

Legumes processing involves large amounts of water to remove anti-nutrients, reduce uncomfortable effects, and improve organoleptic characteristics. This procedure generates waste and high levels of environmental pollution. This work aims to evaluate the galacto-oligosaccharide (GOS) and general carbohydrate composition of legume wastewaters and assess their potential for growing lactic acid bacteria. Legume wastewater extracts were produced by soaking and/or cooking the dry seeds of chickpeas and lentils in distilled water and analysed using high-performance liquid chromatography with refractive index detection. GOS were present in all extracts, which was also confirmed by Fourier transform infrared spectroscopy (FTIR). C-BW extract, produced by cooking chickpeas without soaking, provided the highest extraction yield of 3% (g/100 g dry seeds). Lentil extracts were the richest source of GOS with degree of polymerization ≥ 5 (0.4%). Lactiplantibacillus plantarum CIDCA 83114 was able to grow in de Man, Rogosa, and Sharpe (MRS) broth prepared by replacing the glucose naturally present in the medium with chickpeas' and lentils' extracts. Bacteria were able to consume the mono and disaccharides present in the media with extracts, as demonstrated by HPLC and FTIR. These results provide support for the revalorisation of chickpeas' and lentils' wastewater, being also a sustainable way to purify GOS by removing mono and disaccharides from the mixtures.

Dietary fibre definition revisited - The case of low molecular weight carbohydrates

Low molecular weight (LMW) non-digestible carbohydrates (namely, oligosaccharides and inulin) are accepted as dietary fibre in many countries worldwide. The inclusion of oligosaccharides as dietary fibre was made optional within the Codex Alimentarius definition in 2009, which has caused great controversy. Inulin is accepted as dietary fibre by default, due to being a non-digestible carbohydrate polymer. Oligosaccharides and inulin occur naturally in numerous foods and are frequently incorporated into commonly consumed food products for a variety of purposes, such as to increase dietary fibre content. LMW non-digestible carbohydrates, due to their rapid fermentation in the proximal colon, may cause deleterious effects in individuals with functional bowel disorders (FBDs) and, as such, are excluded on the low FODMAP (fermentable oligosaccharides, disaccharides, and polyols) diet and similar protocols. Their addition to food products as dietary fibre allows the use of associated nutrition/health claims, causing a paradox for those with FBDs, which is further complicated by lack of clarity on food labelling. Therefore, this review aimed to discuss whether the inclusion of LMW non-digestible carbohydrates within the Codex definition of dietary fibre is warranted. This review provides justification for the exclusion of oligosaccharides and inulin from the Codex definition of dietary fibre. LMW non-digestible carbohydrates could, instead, be placed in their own category as prebiotics, recognised for their specific functional properties, or considered food additives, whereby they are not promoted for being beneficial for health. This would preserve the concept of dietary fibre being a universally beneficial dietary component for all individuals.

Targeted gene manipulation of Leloir pathway genes for the constitutive expression of β-galactosidase and its transgalactosylation product galacto-oligosaccharides from Kluyveromyces lactis GG799 and knockout strains

Galacto-oligosaccharides (GOS) are used as prebiotic ingredients in various food and pharmaceutical industry. At present, production of GOS involves the enzymatic transformation of lactose by transgalactosylation using β-galactosidase. The yeast Kluyveromyces lactis can utilize lactose as its carbon and energy source. In this species lactose is hydrolyzed by an intracellular β-galactosidase (EC 3.2.1.23) which is induced by its substrate and related compounds like galactose. The molecular details of gene regulation in kluyveromyces lactis, we have used multiple knockout approaches to study the constitutive expression by which galactose induces β-galactosidase. The present study involved carrying out to a method of enhancing the constitutive expression of β-galactosidase through galactose induction and its trans-galactosylation reaction for the production of galacto-oligosaccharides (GOS) in Kluyveromyces lactis (K. Lactis) by applying a knockout based approach on Leloir pathway genes based on fusion-overlap extension polymerase chain reaction and transformation into its genome. The k.lactis strain subjected to Leloir pathway genes knockout, resulted in the accumulation of galactose intracellularly and this internal galactose acts as an inducer of galactose regulon for constitutive expression of β-galactosidase at early stationary phase was due to the positive regulatory function of mutant gal1p, gal7p and both. These resulted strains used for trans-galactosylation of lactose by β - galactosidase is characterized for the production of galacto-oligosaccharides. Galactose-induced constitutive expression of β-galactosidase during the early stationary phase of knockout strains was analysed qualitatively & quantitatively. The activity of β-galactosidase of wild type, gal1z, gal7k and gal1z & gal7k strains were 7, 8, 9 and 11 U/ml respectively using high cell density cultivation medium. Based on these expression differences in β-galactosidase, the trans-galactosylation reaction for GOS production and percentage yield of GOS were compared at 25% w/v of lactose. The percentage yield of GOS production of wild type, Δgal1z Lac4+, Δgal7k Lac4++ and Δgal1z Δgal7k Lac4+++mutants strains were 6.3, 13, 17 and 22 U/ml, respectively. Therefore, we propose that the availability of galactose can be used for constitutive over expression of β - galactosidase in Leloir pathway engineering applications and also for GOS production. Further, increased expression of β - galactosidases can be used in dairy industry by-products like whey to produce added value products such as galacto-oligosaccharides.

Nondigestible Functional Oligosaccharides: Enzymatic Production and Food Applications for Intestinal Health

Nondigestible functional oligosaccharides are of particular interest in recent years because of their unique prebiotic activities, technological characteristics, and physiological effects. Among different types of strategies for the production of nondigestible functional oligosaccharides, enzymatic methods are preferred owing to the predictability and controllability of the structure and composition of the reaction products. Nondigestible functional oligosaccharides have been proved to show excellent prebiotic effects as well as other benefits to intestinal health. They have exhibited great application potential as functional food ingredients for various food products with improved quality and physicochemical characteristics. This article reviews the research progress on the enzymatic production of several typical nondigestible functional oligosaccharides in the food industry, including galacto-oligosaccharides, xylo-oligosaccharides, manno-oligosaccharides, chito-oligosaccharides, and human milk oligosaccharides. Moreover, their physicochemical properties and prebiotic activities are discussed as well as their contributions to intestinal health and applications in foods.

Production, Kinetic/Thermodynamic Study, and Evaluation of the Influence of Static Magnetic Field on Kinetic Parameters of β-Fructofuranosidase from Aspergillus tamarii Kita UCP 1279 Produced by Solid-State Fermentation

β-fructofuranosidases (FFases) are enzymes involved in sucrose hydrolysis and can be used in the production of invert sugar and fructo-oligosaccharides (FOS). This last is an important prebiotic extensively used in the food industry. In the present study, the FFase production by Aspergillus tamarii Kita UCP 1279 was assessed by solid-state fermentation using a mixture of wheat and soy brans as substrate. The FFase presents optimum pH and temperature at 5.0–7.0 and 60 °C, respectively. According to the kinetic/thermodynamic study, the FFase was relatively stable at 50 °C, a temperature frequently used in industrial FOS synthesis, using sucrose as substrate, evidenced by the parameters half-life (115.52 min) and D-value (383.76 min) and confirmed by thermodynamic parameters evaluated. The influence of static magnetic field with a 1450 G magnetic flux density presented a positive impact on FFase kinetic parameters evidenced by an increase of affinity of enzyme by substrate after exposition, observed by a decrease of 149.70 to 81.73 mM on Km. The results obtained indicate that FFases present suitable characteristics for further use in food industry applications. Moreover, the positive influence of a magnetic field is an indicator for further developments of bioprocesses with the presence of a magnetic field.

Strategies for Producing Low FODMAPs Foodstuffs: Challenges and Perspectives

In recent years, there has been a growing interest in a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) as a promising therapeutic approach to reduce the symptoms associated with irritable bowel syndrome (IBS). Hence, the development of low FODMAPs products is an important challenge for the food industry, and among the various foodstuffs associated with the intake of FODMAPs, cereal-based products represent an issue. In fact, even if their content in FODMAPs is limited, their large use in diet can be an important factor in developing IBS symptoms. Several useful approaches have been developed to reduce the FODMAPs content in processed food products. Accurate ingredient selection, the use of enzymes or selected yeasts, and the use of fermentation steps carried out by specific lactic bacteria associated with the use of sourdough represent the technical approaches that have been investigated, alone or in combination, to reduce the FODMAPs content in cereal-based products. This review aims to give an overview of the technological and biotechnological strategies applicable to the formulation of low-FODMAPs products, specifically formulated for consumers affected by IBS. In particular, bread has been the foodstuff mainly investigated throughout the years, but information on other raw or processed products has also been reported. Furthermore, taking into account the required holistic approach for IBS symptoms management, in this review, the use of bioactive compounds that have a positive impact on reducing IBS symptoms as added ingredients in low-FODMAPs products is also discussed.

Dietary fiber from fruit waste as a potential source of metabolites in maintenance of gut milieu during ulcerative colitis: A comprehensive review

The prevalence of inflammatory bowel disease, particularly ulcerative colitis (UC), has increased dramatically in the past few years owing to a changed lifestyle. Despite various therapeutic treatments, management of the disease is still an issue due to several limitations, including cost and adverse reactions. In this regard, researchers and consumers are inclined towards natural herbal medicines and prophylactic agents. Of these, dietary fiber (DF) (polysaccharides) has become an important topic of interest owing to various putative health attributes, particularly for diseases associated with the large intestine, such as UC. To fulfil industrial and scientific demands of dietary fibers, waste utilization can prove advantageous. Here, the present review highlights recent comprehensive advances in dietary fiber from waste resources in improving UC. Additionally, their role in the gut-associated microbiome, pathway for metabolites synthesis, inflammation, and its mediators. Moreover, here we also discussed short-chain fatty acids (SCFAs) transport and epithelial barrier function along with the mechanism of inflammation regulation. Collectively, it depicts dietary fiber from waste resources that could regulate various cellular processes and molecular mechanisms involved in perpetuating UC and can be used as a promising therapeutic candidate.

Antibiotics in avian care and husbandry-status and alternative antimicrobials

Undoubtedly, the discovery of antibiotics was one of the greatest milestones in the treatment of human and animal diseases. Due to their over-use mainly as antibiotic growth promoters (AGP) in livestock farming, antimicrobial resistance has been reported with increasing intensity, especially in the last decades. In order to reduce the scale of this phenomenon, initially in the Scandinavian countries and then throughout the entire European Union, a total ban on the use of AGP was introduced, moreover, a significant limitation in the use of these feed additives is now observed almost all over the world. The withdrawal of AGP from widespread use has prompted investigators to search for alternative strategies to maintain and stabilize the composition of the gut microbiota. These strategies include substances that are used in an attempt to stimulate the growth and activity of symbiotic bacteria living in the digestive tract of animals, as well as living microorganisms capable of colonizing the host’s gastrointestinal tract, which can positively affect the composition of the intestinal microbiota by exerting a number of pro-health effects, i.e., prebiotics and probiotics, respectively. In this review we also focused on plants/herbs derived products that are collectively known as phytobiotic.

The Appearance and Establishment of Breastfeeding Amongst Animals: From Echidna and Platypus to Mammals and Human

The paper provides review of the scientific literature dedicated to the evolutionary aspects of breastfeeding in the animal kingdom. Differences in breast milk composition amongst different mammals along with changes in breast milk composition during evolution provided. Special attention is paid to oligosaccharides — unique components of the breast milk of Homo sapiens.

Continuous process technology for bottom-up synthesis of soluble cello-oligosaccharides by immobilized cells co-expressing three saccharide phosphorylases

BACKGROUND

Continuous processing with enzyme reuse is a well-known engineering strategy to enhance the efficiency of biocatalytic transformations for chemical synthesis. In one-pot multistep reactions, continuous processing offers the additional benefit of ensuring constant product quality via control of the product composition. Bottom-up production of cello-oligosaccharides (COS) involves multistep iterative β-1,4-glycosylation of glucose from sucrose catalyzed by sucrose phosphorylase from Bifidobacterium adeloscentis (BaScP), cellobiose phosphorylase from Cellulomonas uda (CuCbP) and cellodextrin phosphorylase from Clostridium cellulosi (CcCdP). Degree of polymerization (DP) control in the COS product is essential for soluble production and is implemented through balance of the oligosaccharide priming and elongation rates. A whole-cell E. coli catalyst co-expressing the phosphorylases in high yield and in the desired activity ratio, with CdP as the rate-limiting enzyme, was reported previously.

RESULTS

Freeze-thaw permeabilized E. coli cells were immobilized in polyacrylamide (PAM) at 37-111 mg dry cells/g material. PAM particles (0.25-2.00 mm size) were characterized for COS production (~ 70 g/L) in mixed vessel with catalyst recycle and packed-bed reactor set-ups. The catalyst exhibited a dry mass-based overall activity (270 U/g; 37 mg cells/g material) lowered by ~ 40% compared to the corresponding free cells due to individual enzyme activity loss, CbP in particular, caused by the immobilization. Temperature studies revealed an operational optimum at 30 °C for stable continuous reaction (~ 1 month) in the packed bed (volume: 40 mL; height: 7.5 cm). The optimum reflects the limits of PAM catalyst structural and biological stability in combination with the requirement to control COS product solubility in order to prevent clogging of the packed bed. Using an axial flow rate of 0.75 cm- 1, the COS were produced at ~ 5.7 g/day and ≥ 95% substrate conversion (sucrose 300 mM). The product stream showed a stable composition of individual oligosaccharides up to cellohexaose, with cellobiose (48 mol%) and cellotriose (31 mol%) as the major components.

CONCLUSIONS

Continuous process technology for bottom-up biocatalytic production of soluble COS is demonstrated based on PAM immobilized E. coli cells that co-express BaScP, CuCbP and CcCdP in suitable absolute and relative activities.

Non-Digestible Oligosaccharides: A Novel Treatment for Respiratory Infections?

Emerging antimicrobial resistance in respiratory infections requires novel intervention strategies. Non-digestible oligosaccharides (NDOs) are a diverse group of carbohydrates with broad protective effects. In addition to promoting the colonization of beneficial gut microbiota and maintaining the intestinal homeostasis, NDOs act as decoy receptors, effectively blocking the attachment of pathogens on host cells. NDOs also function as a bacteriostatic agent, inhibiting the growth of specific pathogenic bacteria. Based on this fact, NDOs potentiate the actions of antimicrobial drugs. Therefore, there is an increasing interest in characterizing the anti-infective properties of NDOs. This focused review provides insights into the mechanisms by which representative NDOs may suppress respiratory infections by targeting pathogens and host cells. We summarized the most interesting mechanisms of NDOs, including maintenance of gut microbiota homeostasis, interference with TLR-mediated signaling, anti-oxidative effects and bacterial toxin neutralization, bacteriostatic and bactericidal effects, and anti-adhesion or anti-invasive properties. A detailed understanding of anti-infective mechanisms of NDOs against respiratory pathogens may contribute to the development of add-on therapy or alternatives to antimicrobials.

A Review on Psychrophilic β-D-Galactosidases and Their Potential Applications

The majority of the Earth's ecosystem is frigid and frozen, which permits a vast range of microbial life forms to thrive by triggering physiological responses that allow them to survive in cold and frozen settings. The apparent biotechnology value of these cold-adapted enzymes has been targeted. Enzymes' market size was around USD 6.3 billion in 2017 and will witness growth at around 6.8% CAGR up to 2024 owing to shifting consumer preferences towards packaged and processed foods due to the rising awareness pertaining to food safety and security reported by Global Market Insights (Report ID-GMI 743). Various firms are looking for innovative psychrophilic enzymes in order to construct more effective biochemical pathways with shorter reaction times, use less energy, and are ecologically acceptable. D-Galactosidase catalyzes the hydrolysis of the glycosidic oxygen link between the terminal non-reducing D-galactoside unit and the glycoside molecule. At refrigerated temperature, the stable structure of psychrophile enzymes adjusts for the reduced kinetic energy. It may be beneficial in a wide variety of activities such as pasteurization of food, conversion of biomass, biological role of biomolecules, ambient biosensors, and phytoremediation. Recently, psychrophile enzymes are also used in claning the contact lens. β-D-Galactosidases have been identified and extracted from yeasts, fungi, bacteria, and plants. Conventional (hydrolyzing activity) and nonconventional (non-hydrolytic activity) applications are available for these enzymes due to its transgalactosylation activity which produce high value-added oligosaccharides. This review content will offer new perspectives on cold-active β-galactosidases, their source, structure, stability, and application.

High-yield production and purification of prebiotic inulin-type fructooligosaccharides

Due to the health-promoting effects and functional properties of inulin-type fructooligosaccharides (I-FOS), the global market for I-FOS is constantly growing. Hence, there is a continuing demand for new, efficient biotechnological approaches for I-FOS production. In this work, crude inulosucrase InuGB-V3 from Lactobacillus gasseri DSM 20604 was used to synthesize I-FOS from sucrose. Supplementation with 1 mM CaCl2, a pH of 3.5–5.5, and an incubation temperature of 40 °C were found to be optimal production parameters at which crude inulosucrase showed high conversion rates, low sucrose hydrolysis, and excellent stability over 4 days. The optimal process conditions were employed in cell-free bioconversion reactions. By elevating the substrate concentration from 570 to 800 g L−1, the I-FOS concentration and the synthesis of products with a low degree of polymerization (DP) could be increased, while sucrose hydrolysis was decreased. Bioconversion of 800 g L−1 sucrose for 20 h resulted in an I-FOS-rich syrup with an I-FOS concentration of 401 ± 7 g L−1 and an I-FOS purity of 53 ± 1% [w/w]. I-FOS with a DP of 3–11 were synthesized, with 1,1-kestotetraose (DP4) being the predominant transfructosylation product. The high-calorie sugars glucose, sucrose, and fructose were removed from the generated I-FOS-rich syrup using activated charcoal. Thus, 81 ± 5% of the initially applied I-FOS were recovered with a purity of 89 ± 1%.

Intestinal microbiota in the treatment of metabolically associated fatty liver disease

Metabolically associated fatty liver disease (MAFLD) is a common cause of chronic liver disease, the hepatic manifestation of metabolic syndrome. Despite the increasing incidence of MAFLD, no effective treatment is available. Recent research indicates a link between the intestinal microbiota and liver diseases such as MAFLD. The composition and characteristics of the intestinal microbiota and therapeutic perspectives of MAFLD are reviewed in the current study. An imbalance in the intestinal microbiota increases intestinal permeability and exposure of the liver to adipokines. Furthermore, we focused on reviewing the latest "gut-liver axis" targeted therapy.

Inulin-type fructans and short-chain fructooligosaccharides-their role within the food industry as fat and sugar replacers and texture modifiers-what needs to be considered!

Inulin and oligofructose are classes of prebiotics belonging to a group of nondigestible carbohydrates referred to as inulin-type fructans. While short-chain fructooligosaccharides are enzymatically synthesized from the hydrolysis and transglycosylation of sucrose. Inulin-type fructans and short-chain fructooligosaccharides act as carbon sources for selective pathways supporting digestive health including altering the composition of the gut microbiota along with improving transit time. Due to their physicochemical properties, inulin-type fructans and short-chain fructooligosaccharides have been widely used in the food industry as partial replacements for both fat and sugar. Yet, levels of replacement need to be carefully considered as it may result in changes to physical and sensory properties that could be detected by consumers. Furthermore, it has been reported depending on the processing parameters used during production that inulin-type fructans and short-chain fructooligosaccharides may or may not undergo structural alterations. Therefore, this paper reviews the role of inulin-type fructans and short-chain fructooligosaccharides within the food industry as fat and sugar replacers and texture modifiers, their impact on final sensory properties, and to what degree processing parameters are likely to impact their functional properties.

Colon microbiota modulation by dairy-derived diet: new strategy for prevention and treatment of colorectal cancer

An unbalanced diet is one of the well-known risk factors for the development of colorectal cancer (CRC). This type of cancer is currently the main cause of cancer-related deaths worldwide, urging the need for new and more effective preventive and therapeutic approaches. It is already known that CRC patients have alterations in the microbial community and metabolism. In this regard, a concept that has been recently attracting the attention of the scientific community is the development of functional food or nutraceuticals, as a new and more effective strategy to overcome CRC patient-associated dysbiosis. Particularly, dairy product enriched diets are the major dairy source of dietary calcium, vitamin D and folate intake, which are well-known to have a protective effect against CRC development. In addition, these products are rich in both pre- and probiotics, constituting a double strategy to modulate both the intestinal microbiota composition and the production of microbial metabolites. Short-chain fatty acids (SCFA), namely, acetate, butyrate, and propionate, are major contributors to colonic homeostasis since they regulate several biological and metabolic processes. In this review, we performed a state of art study concerning the use of dietary patterns, specifically the dairy-derived diet, in the modulation of the human microbiota and their potential use as pre-, pro- or synbiotics for the development of new preventive and therapeutic strategies for CRC.

Dataset on the Life Cycle Assessment of fructo- and galacto-oligosaccharides (FOS and GOS) produced by synthesis or hydrolysis

The prebiotics like FOS and GOS are receiving special attention in the food industry due to their potential health benefits. They can be produced by enzymatic synthesis by using disaccharides or other substrates as raw materials or by extraction and hydrolysis from different natural sources (roots, legumes). However the environmental footprints of these different production schemes are lacking. This dataset presents Life Cycle Assessment (LCA) of the production of FOS and GOS by enzymatic synthesis from glucose (to get FOS) or lactose (to get GOS) and hydrolytic production from extraction of yacon potato (to get FOS) or chickpea (to get GOS). A cradle-to-gate approach was considered in the two scenarios under assessment (the phases of use and/or final disposal of FOS/GOS were not considered). The functional unit was defined as 100 g of FOS/GOS produced. LCAs were performed using data collected at the laboratory scale during experiments, supplemented with data from technical and scientific literature. Ecoinvent database provided background data. SimaPro was used for the LCA modeling with the midpoint impact EF2.0 characterization method to calculate environmental impacts. For each scenario (FOS produced by synthesis, FOS produced by hydrolysis, GOS produced by synthesis, GOS produced by hydrolysis), the Life Cycle Inventory (LCI) and the Life Cycle Impact Assessment (LCIA) are provided. These data can be used (i) to identify the main environmental hotspots of the production process, (ii) to compare the different process alternatives between them and (ii) to suggest eco-design options to upscale these processes. They could also be re-used in other LCA studies which would include FOS and/or GOS in the production system.

Prebiotic Potential of a New Sweetener Based on Galactooligosaccharides and Modified Mogrosides

This study was conducted to investigate the sweetness intensity and the potential fecal microbiome modulation of galactooligosaccharides in combination with enzymatically modified mogrosides (mMV-GOS), both generated through a patented single-pot synthesis. Sweetness intensity was performed in vivo by trained sensory panelists. The impact on the human fecal microbiome was evaluated by in vitro pH-controlled batch fermentation, and bacterial populations and organic acid concentrations were measured by qPCR and GC-FID, respectively. Significant growth (p ≤ 0.05) during the fermentation at 10 h of bacterial populations includes Bifidobacterium (8.49 ± 0.44 CFU/mL), Bacteroides (9.73 ± 0.32 CFU/mL), Enterococcus (8.17 ± 0.42 CFU/mL), and Clostridium coccoides (6.15 ± 0.11 CFU/mL) as compared to the negative control counts for each bacterial group (7.94 ± 0.27, 7.84 ± 1.11, 7.52 ± 0.37, and 5.81 ± 0.08 CFU/mL, respectively) at the same time of fermentation. Likewise, the corresponding significant increase in production of SCFA in mMV-GOS at 10 h of fermentation, mainly seen in acetate (20.32 ± 2.56 mM) and propionate (9.49 ± 1.44 mM) production compared to a negative control at the same time (8.15 ± 1.97 and 1.86 ± 0.24 mM), is in line with a positive control (short-chain fructooligosaccharides; 46.74 ± 12.13 and 6.51 ± 1.91 mM, respectively) revealing a selective fermentation. In conclusion, these substrates could be considered as novel candidate prebiotic sweeteners, foreseeing a feasible and innovative approach targeting the sucrose content reduction in food. This new ingredient could provide health benefits when evaluated in human studies by combining sweetness and prebiotic fiber functionality.

Evaluation of Prebiotic Properties of Galactooligosaccharides Produced by Transgalactosylation Using Partially Purified β-Galactosidase from Enterobacter aerogenes KCTC2190

Transgalactosylation reaction is the penultimate step in the production of galactooligosaccharides (GOSs) which has prominent applications in the treatment of disorders. In the present study, partially purified β-galactosidase from Enterobacter aerogenes KCTC2190 was used for the synthesis of prebiotic GOSs. GOSs were produced using lactose as substrate. Structural elucidation of collected fractions of GOSs by liquid chromatography electrospray ionization mass spectrometry exhibited the appearance of major peaks of produced GOSs at m/z 241.20, 481.39, 365.11, 527.17, and 701.51 respectively. GOSs facilitated the growth of potential probiotic strains (Lactobacillus delbrueckii ssp. helveticus, Bifidobacterium bifidum, and Lactiplantibacillus plantarum) and liberated propionate and butyrate as principal short-chain fatty acids which established its prebiotic potency. Synbiotic combinations exhibited good antioxidant activities. Synbiotic combinations also exhibited antimicrobial activities against pathogenic microorganisms namely Staphylococcus aureus and Escherichia coli. Synbiotic combinations of GOSs and the respective probiotic microorganisms were able to decrease viable human bone cancer cells (MG-63).

Study Protocol for a Randomised Controlled Trial Investigating the Effects of Maternal Prebiotic Fibre Dietary Supplementation from Mid-Pregnancy to Six Months’ Post-Partum on Child Allergic Disease Outcomes

Infant allergy is the most common early manifestation of an increasing propensity for inflammation and immune dysregulation in modern environments. Refined low-fibre diets are a major risk for inflammatory diseases through adverse effects on the composition and function of gut microbiota. This has focused attention on the potential of prebiotic dietary fibres to favourably change gut microbiota, for local and systemic anti-inflammatory effects. In pregnancy, the immunomodulatory effects of prebiotics may also have benefits for the developing fetal immune system, and provide a potential dietary strategy to reduce the risk of allergic disease. Here, we present the study protocol for a double-blinded, randomised controlled trial investigating the effects of maternal prebiotics supplementation on child allergic disease outcomes. Eligible pregnant women have infants with a first-degree relative with a history of medically diagnosed allergic disease. Consented women are randomised to consume either prebiotics (galacto-oligosaccharides and fructo-oligosaccharides) or placebo (maltodextrin) powder daily from 18–20 weeks’ gestation to six months’ post-partum. The target sample size is 652 women. The primary outcome is infant medically diagnosed eczema; secondary outcomes include allergen sensitisation, food allergies and recurrent wheeze. Breast milk, stool and blood samples are collected at multiple timepoints for further analysis.

Prebiotics, Probiotics, and Postbiotics in the Prevention and Treatment of Anemia

Iron deficiency anemia (IDA) is very common and affects approximately 1/3 of the world’s human population. There are strong research data that some probiotics, such as Lactobacillus acidophilus and Bifidobacterium longum improve iron absorption and influence the course of anemia. Furthermore, prebiotics, including galactooligosaccharides (GOS) and fructooligosaccharides (FOS), increase iron bioavailability and decrease its destructive effect on the intestinal microbiota. In addition, multiple postbiotics, which are probiotic metabolites, including vitamins, short-chain fatty acids (SCFA), and tryptophan, are involved in the regulation of intestinal absorption and may influence iron status in humans. This review presents the actual data from research studies on the influence of probiotics, prebiotics, and postbiotics on the prevention and therapy of IDA and the latest findings regarding their mechanisms of action. A comparison of the latest research data and theories regarding the role of pre-, post-, and probiotics and the mechanism of their action in anemias is also presented and discussed.

Rapid, real-time sucrase characterization: Showcasing the feasibility of a one-pot activity assay

Sucrases can modify numerous carbohydrates, and short-chain oligosaccharides produced by the unique transfructosylation activity of levansucrases are promising candidates for the growing sugar substitute market. These compounds could counteract the increasing number of diseases associated with the consumption of high-calorie sugars. Thus, there is great interest in the characterization of novel levansucrases. The commonly used method for sucrase activity determination is to quantify d-glucose released in the sucrose-splitting reaction. This is usually done in a discontinuous mode, i.e., several samples taken from the sucrase reaction are applied to a separately performed d-glucose determination (e.g., GOPOD assay). Employing the newly isolated levansucrase LevS_KK21 from Pseudomonas sp. KK21, the feasibility of a one-pot sucrase characterization was investigated by combining sucrase reaction and GOPOD-based d-glucose determination into a single, continuous assay (Real-time GOPOD). The enzyme was characterized with respect to kinetic parameters, ion dependency, pH value, and reaction temperature in a comparative approach employing Real-time GOPOD and HPLC. High data consistency for all investigated enzyme parameters demonstrated that current processes for sucrase characterization can be considerably accelerated by the continuous assay while maintaining data validity. However, the assay was not applicable at acidic pH, as decolorization of the quinoneimine dye formed during the GOPOD reaction was observed. Overall, the study presents valuable data on the potentials of real-time sucrase activity assessment for an accelerated discovery and characterization of interesting enzymes such as the hereby introduced levansucrase LevS_KK21. Progress in sucrase discovery will finally foster the development of health-promoting sucrose substitutes.

Application of oligosaccharides in meat processing and preservation

In recent decades, consumer preference and attention to foodstuff presented as healthy and with desirable nutritional information, has increased significantly. In this field, the meat industry has a challenging task since meat and meat products have been related to various chronic diseases. Functional ingredients have emerged in response to the increasing demand for healthier and more nutritious foods. On this matter, oligosaccharides such as fructooligosaccharides (FOS), xylooligosaccharides (XOS), galactooligosaccharides (GOS), and chitooligosaccharides (COS) have been presented as suitable ingredients for the meat industry with the aim of obtaining healthier meat derivatives (e.g. with low fat or sugar content, reduced amount of additives, and desirable functional properties, etc.). However, studies considering application of such oligomers in the meat sector are scarce. In addition, a large number of issues remain to be solved related both to obtaining and characterizing the oligosaccharides available in the industry and to the effect that these ingredients have on the features of meat products (mainly physicochemical and sensory). The study of new oligosaccharides, the methodologies for obtaining them, and their application to new meat products should be promoted, as well as improving knowledge about their effects on the properties of functional meat foods.

Engineering cascade biocatalysis in whole cells for bottom-up synthesis of cello-oligosaccharides: flux control over three enzymatic steps enables soluble production

BACKGROUND

Soluble cello-oligosaccharides (COS, β-1,4-D-gluco-oligosaccharides with degree of polymerization DP 2-6) have been receiving increased attention in different industrial sectors, from food and feed to cosmetics. Development of large-scale COS applications requires cost-effective technologies for their production. Cascade biocatalysis by the three enzymes sucrose-, cellobiose- and cellodextrin phosphorylase is promising because it enables bottom-up synthesis of COS from expedient substrates such as sucrose and glucose. A whole-cell-derived catalyst that incorporates the required enzyme activities from suitable co-expression would represent an important step towards making the cascade reaction fit for production. Multi-enzyme co-expression to reach distinct activity ratios is challenging in general, but it requires special emphasis for the synthesis of COS. Only a finely tuned balance between formation and elongation of the oligosaccharide precursor cellobiose results in the desired COS.

RESULTS

Here, we show the integration of cellodextrin phosphorylase into a cellobiose-producing whole-cell catalyst. We arranged the co-expression cassettes such that their expression levels were upregulated. The most effective strategy involved a custom vector design that placed the coding sequences for cellobiose phosphorylase (CbP), cellodextrin phosphorylase (CdP) and sucrose phosphorylase (ScP) in a tricistron in the given order. The expression of the tricistron was controlled by the strong T7_lacO promoter and strong ribosome binding sites (RBS) for each open reading frame. The resulting whole-cell catalyst achieved a recombinant protein yield of 46% of total intracellular protein in an optimal ScP:CbP:CdP activity ratio of 10:2.9:0.6, yielding an overall activity of 315 U/g dry cell mass. We demonstrated that bioconversion catalyzed by a semi-permeabilized whole-cell catalyst achieved an industrial relevant COS product titer of 125 g/L and a space-time yield of 20 g/L/h. With CbP as the cellobiose providing enzyme, flux into higher oligosaccharides (DP ≥ 6) was prevented and no insoluble products were formed after 6 h of conversion.

CONCLUSIONS

A whole-cell catalyst for COS biosynthesis was developed. The coordinated co-expression of the three biosynthesis enzymes balanced the activities of the individual enzymes such that COS production was maximized. With the flux control set to minimize the share of insolubles in the product, the whole-cell synthesis shows a performance with respect to yield, productivity, product concentration and quality that is promising for industrial production.

Galacto-Oligosaccharide (GOS) Synthesis during Enzymatic Lactose-Free Milk Production: State of the Art and Emerging Opportunities

Much attention has recently been paid to β-Galactosidases (β-D-galactoside galactohidrolase; EC 3.2.1.23), commonly known as lactases, due to the lactose intolerance of the human population and the importance of dairy products in the human diet. This enzyme, produced by microorganisms, is being used in the dairy industry for hydrolyzing the lactose found in milk to produce lactose-free milk (LFM). Conventionally, β-galactosidases catalyze the hydrolysis of lactose to produce glucose and galactose in LFM; however, they can also catalyze transgalactosylation reactions that produce a wide range of galactooligosaccharides (GOS), which are functional prebiotic molecules that confer health benefits to human health. In this field, different works aims to identify novel microbial sources of β-galactosidase for removing lactose from milk with the relative GOS production. Lactase extracted from thermophilic microorganisms seems to be more suitable for the transgalactosylation process at relatively high temperatures, as it inhibits microbial contamination. Different immobilization methods, such as adsorption, covalent attachment, chemical aggregation, entrapment and micro-encapsulation, have been used to synthesize lactose-derived oligosaccharides with immobilized β-galactosidases. In this mini-review, particular emphasis has been given to the immobilization techniques and bioreactor configurations developed for GOS synthesis in milk, in order to provide a more detailed overview of the biocatalytic production of milk oligosaccharides at industrial level.

Gut microbiota and inflammation in Parkinson’s disease: Pathogenetic and therapeutic insights

Parkinson’s disease (PD) is a progressive neurodegenerative disease characterized by dopaminergic neuronal loss and α-synuclein (α-syn) aggregation. With the acceleration of population aging process, the incidence of PD is expected to increase, putting a heavy burden on the whole society. Recent studies have found the alterations of gut microbiota (GM) in PD patients and the clinical relevance of these changes, indicating the underlying relationship between GM and PD. Additionally, elevated inflammatory responses originating from the gut play a crucial role in the initiation and progression of PD, which is closely associated with GM. In this review, we will summarize recent studies on the correlation between GM and PD, and discuss the possible pathogenesis of PD mediated by GM and subsequent inflammatory cascades. We will also focus on the promising GM-based therapeutic strategies of PD, including antibiotics, probiotics and/or prebiotics, fecal microbiota transplantation, and dietary interventions, aiming to provide some new therapeutic insights for PD.

Cellobiose phosphorylase from Caldicellulosiruptor bescii catalyzes reversible phosphorolysis via different kinetic mechanisms

In the process of yielding biofuels from cellulose degradation, traditional enzymatic hydrolysis, such as β-glucosidase catalyzing cellobiose, can barely resolve the contradiction between cellulose degradation and bioenergy conservation. However, it has been shown that cellobiose phosphorylase provides energetic advantages for cellobiose degradation through a phosphorolytic pathway, which has attracted wide attention. Here, the cellobiose phosphorylase gene from Caldicellulosiruptor bescii (CbCBP) was cloned, expressed, and purified. Analysis of the enzymatic properties and kinetic mechanisms indicated that CbCBP catalyzed reversible phosphorolysis and had good thermal stability and broad substrate selectivity. In addition, the phosphorolytic reaction of cellobiose by CbCBP proceeded via an ordered Bi Bi mechanism, while the synthetic reaction proceeded via a ping pong Bi Bi mechanism. The present study lays the foundation for optimizing the degradation of cellulose and the synthesis of functional oligosaccharides.

Valorization of renewable resources to functional oligosaccharides: Recent trends and future prospective

Lignocellulosic wastes have the ability to be transformed into oligosaccharides and other value-added products. The synthesis of oligosaccharides from renewable sources bestow to growing bioeconomies. Oligosaccharides are synthesized chemically or biologically from agricultural residues. These oligosaccharides are functional food supplements that have a positive impact on humans and livestock. Non-digestible oligosaccharides, refered as prebiotics are beneficial for the colonic microbiota inhabiting the f the digestive system. These microbiota plays a crucial role in stimulating the host immune system and other physiological responses. The commonly known prebiotics, galactooligosaccharides (GOS), xylooligosaccharides (XOS), fructooligosaccharides (FOS), mannanooligosaccharides (MOS), and isomaltooligosaccharides (IOS) are synthesized either through enzymatic or whole cell-mediated approaches using natural or agricultural waste substrates. This review focusses on recent advancements in biological processes, for the synthesis of oligosaccharides using renewable resources (lignocellulosic substrates) for sustainable circular bioeconomy. The work also addresses the limitations associated with the processes and commercialization of the products.

Trends in lactose-derived bioactives: synthesis and purification

Lactose obtained from cheese whey is a low value commodity despite its great potential as raw material for the production of bioactive compounds. Among them, prebiotics stand out as valuable ingredients to be added to food matrices to build up functional foods, which currently represent the most active sector within the food industry. Functional foods market has been growing steadily in the recent decades along with the increasing awareness of the World population about healthy nutrition, and this is having a strong impact on lactose-derived bioactives. Most of them are produced by enzyme biocatalysis because of molecular precision and environmental sustainability considerations. The current status and outlook of the production of lactose-derived bioactive compounds is presented with special emphasis on downstream operations which are critical because of the rather modest lactose conversion and product yields that are attainable. Even though some of these products have already an established market, there are still several challenges referring to the need of developing better catalysts and more cost-effective downstream operations for delivering high quality products at affordable prices. This technological push is expected to broaden the spectrum of lactose-derived bioactive compounds to be produced at industrial scale in the near future.

Graphical abstract

Prebiotic Galacto-oligosaccharides and Fructo-oligosaccharides, but not Acacia Gum, Increase Iron Absorption from a Single High-dose Ferrous Fumarate Supplement in Iron-depleted Women

BACKGROUND

Prebiotic galacto-oligosaccharides (GOS) increase iron absorption from fortification-level iron doses given as ferrous fumarate (FeFum) in women and children. Whether GOS or other fibers, such as prebiotic fructo-oligosaccharides (FOS) and acacia gum, increase iron absorption from higher supplemental doses of FeFum is unclear.

OBJECTIVES

In iron-depleted [serum ferritin (SF)< 25μg/L] women,  we tested if oral co-administration of 15g of GOS, FOS or acacia gum increases iron absorption from a 100mg iron supplement given as FeFum.

METHODS

In a randomized, single-blind cross-over study, 30 women (median age 26.2 years, median SF 12.9μg/L) consumed a 100mg iron tablet labelled with 4mg of 57Fe or 58Fe, given with either: a) 15g GOS; b) 15g FOS; c) 15g acacia gum; or d) 6.1g lactose and 1.5g sucrose (control; matching the amounts of sucrose and lactose present in the GOS powder providing 15 g GOS), dissolved in water. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte isotopic incorporation 14 days after administration. Data were analysed using a linear mixed-effect model. We also tested, in vitro, iron solubility at different pH and dialyzability from the different supplement combinations administered in vivo.

RESULTS

FIA from FeFum given with GOS and FOS was significantly higher (+45% and 51%, respectively; P < 0.001 for both) compared with control; total iron absorption [median (IQR)] was 34.6 (28.4; 49.1); 36.1 (29.0; 46.2) and 23.9 (20.5; 34.0) mg, respectively. Acacia gum did not significantly affect FIA from FeFum (P = 0.688). In vitro, iron dialyzability of FeFum + GOS was 46% higher than of FeFum alone (P = 0.003).

CONCLUSIONS

In iron-depleted women, both GOS and FOS co-administration with FeFum increase iron absorption by ∼50% from a 100mg oral iron dose, resulting in an additional 10-12mg of absorbed iron. Thus, GOS and FOS may be promising new enhancers of supplemental iron absorption.The study was registered at clinicaltrials.gov as NCT04194255 (https://clinicaltrials.gov/ct2/show/NCT04194255).

Heterofunctional epoxy support development for immobilization of fructosyltransferase from Pectinex® Ultra SP-L: batch and continuous production of fructo-oligosaccharides

The FTase from Pectinex® Ultra SP-L was immobilized using a newly developed epoxy-Purolite support with amino and epoxy groups. Continuous production of FOS in the air-lift reactor was established for 7 days (52.47% FOS of total carbohydrates).

β-Galactosidase from Kluyveromyces lactis: Characterization, production, immobilization and applications - A review

A review on the enzyme β-galactosidase from Kluyveromyces lactis is presented, from the perspective of its structure and mechanisms of action, the main catalyzed reactions, the key factors influencing its activity, and selectivity, as well as the main techniques used for improving the biocatalyst functionality. Particular attention was given to the discussion of hydrolysis, transglycosylation, and galactosylation reactions, which are commonly mediated by this enzyme. In addition, the products generated from these processes were highlighted. Finally, biocatalyst improvement techniques are also discussed, such as enzyme immobilization and protein engineering. On these topics, the most recent immobilization strategies are presented, emphasizing processes that not only allow the recovery of the biocatalyst but also deliver enzymes that show better resistance to high temperatures, chemicals, and inhibitors. In addition, genetic engineering techniques to improve the catalytic properties of the β-galactosidases were reported. This review gathers information to allow the development of biocatalysts based on the β-galactosidase enzyme from K. lactis, aiming to improve existing bioprocesses or develop new ones.

Kinetics of iron absorption from ferrous fumarate with and without galacto-oligosaccharides determined from stable isotope appearance curves in women

BACKGROUND

Prebiotic galacto-oligosaccharides (GOS) are novel enhancers of iron absorption from ferrous fumarate (FeFum). However, the mechanism(s) of this effect, and whether it occurs in the proximal or distal gut, are uncertain.

OBJECTIVES

We studied: 1) in vitro, the effect of GOS on iron solubility and dialyzability from FeFum; 2) in volunteers, the absorption kinetics of FeFum given with and without GOS using stable isotope appearance curves (SIAC).

METHODS

We measured iron solubility at various pH and dialyzability from FeFum with and without GOS. In crossover design, iron-depleted women [n = 11; median serum ferritin (SF) 15.2; IQR: 12.6-21.2 µg/L] received 2 14-mg iron doses as labeled (57Fe,58Fe) FeFum 14 d apart with and without 15 g GOS in randomly assigned order. Multiple blood samples were collected over a time period of 24 h and 14 d later to determine SIAC and fractional iron absorption (FIA), respectively. SIAC data were fitted using nonlinear mixed effects modeling to a 1-compartment model with first-order absorption, and AUC and time of peak serum isotope concentration (tmax) were calculated.

RESULTS

Iron dialyzability was 75% higher with GOS (P < 0.001) and iron solubility was more than doubled at pH 4 and 6 with GOS [both P < 0.001]. Mean ± SD AUC (5830.9 ± 4717.3 μg/min with GOS, 4454.0 ± 3260.7 μg/min for control), and median (IQR) FIA (20.3% (8.6%-38.7%) with GOS, and 15.6% (10.6%-24.8% f)or control) were not different with compared to without GOS (P = 0.064; P = 0.080). Mean ±SD tmax was not altered with GOS (3.08 ± 0.47 h with GOS; 2.80 ±0.50 h for control; P = 0.096). Iron bioavailability significantly increased with decreasing SF and this effect was significantly enhanced by GOS (P = 0.037, interaction of GOS with SF).

CONCLUSIONS

GOS increases iron solubility from FeFum at physiological pH characteristic of the proximal duodenum. The absorption kinetics in vivo are consistent with effects on iron absorption in the proximal, rather than distal, parts of the gut. There was no overall effect of GOS on FIA in vivo, but the interaction of GOS and SF on FIA might benefit iron-deficient women, an effect potentially mediated by the higher solubility shown in vitro. This study was registered at clinicaltrials.gov as NCT03996421.