Metabolism of isomalto-oligosaccharides by Lactobacillus reuteri and bifidobacteria

Current state, challenges and future orientations of the applications of lactic acid bacteria exopolysaccharide in foods

In the quest for a balanced diet and better health, the global shift towards nutrient-dense foods highlights the multiple roles of lactic acid bacteria exopolysaccharides (LAB-EPS) in improving food quality and health. This paper offers a comprehensive survey of LAB-EPS, focusing on their classification, biosynthesis pathways and application in the food industry, from dairy products to bakery products and meat. It highlights the impact of LAB-EPS on the texture and sensory qualities of food. Despite their promising prospects, these polysaccharides face various application challenges in the food industry. These include variability in EPS production among LAB strains, complexity in structure-function relationships, and limited understanding of their health benefits. In order to address these issues, the review identifies and suggests future research directions to optimize the production of LAB-EPS, elucidating their health benefit mechanisms, and expanding their application scope. In summary, this review aims to contribute to advance innovation and progress in the food industry by developing healthier food options and deepening the understanding of LAB-EPS in promoting human health.

Potential Prebiotic Effects of Artemisia capillaris-Derived Transglycosylated Product

This study investigated the impact of a transglycosylated product (ACOD) catalyzed by Leuconostoc mesenteroides MKSR dextransucrase using sucrose as a glucosyl donor and both maltose and Artemisia capillaris as acceptors on gut microbiota through fecal fermentation. ACOD promoted the growth of probiotics such as Lactiplantibacillus plantarum, Lacticaseibacillus casei, Lacticaseibacillus rhamnosus GG, and Leuconostoc mesenteroides MKSR, while inhibiting the growth of pathogenic bacteria such as Escherichia coli, E. coli O157:H7, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, Shigella flexneri, Streptococcus mutans, Pseudomonas aeruginosa, and Bacillus cereus during independent cultivation. Fecal fermentation for 24 h revealed that ACOD significantly increased the production of short-chain fatty acids (SCFAs) compared to the blank and fructoooligosaccharide (FOS) groups. Specifically, ACOD led to a 4.5-fold increase in acetic acid production compared to FOSs and a 3.3-fold increase in propionic acid production. Both the ACOD and FOS groups exhibited higher levels of butyric acid than the blank. Notably, ACOD significantly modulated the composition of the gut microbiota by increasing the relative abundances of Lactobacillus and decreasing Escherichia/Shigella and Salmonella. In contrast, FOSs remarkably promoted the growth of Salmonella. These findings suggest that ACOD is a potential candidate for prebiotics that improve the intestinal environment by being actively used by beneficial bacteria.

Metatranscriptomic analysis indicates prebiotic effect of isomalto/malto-polysaccharides on human colonic microbiota in-vitro

Isomalto/malto-polysaccharides (IMMPs) are a novel type of soluble dietary fibres with a prebiotic potential promoting growth of beneficial microbes in the gut. However, the mode of action of IMMPs remains unknown. Previous studies on IMMPs showed an increase in total bacteria, especially lactobacilli, and higher production of short chain fatty acids (SCFA) when IMMPs were fed to rats or used during in vitro fermentation. Here we used metatranscriptomics to investigate how IMMPs with different amounts of α - (1 → 6) glycosidic linkages affected microbial function during incubation with human fecal inoculum. We showed that active microbial community dynamics during fermentation varied depending on the type of IMMP used and that the observed changes were reflected in the community gene expression profiles. Based on metatranscriptome analysis, members of Bacteroides, Lactobacillus and Bifidobacterium were the predominant degraders of IMMPs, and the increased gene expression in these bacteria correlated with high amounts of α - (1 → 6) glycosidic linkages. We also noted an increase in relative abundance of these bacteria and an activation of pathways involved in SCFA synthesis. Our findings could provide a baseline for more targeted approaches in designing prebiotics for specific bacteria and to achieve more controlled modulation of microbial activity towards desired health outcomes.

Selective utilization of gluco-oligosaccharides by lactobacilli: A mechanism study revealing the impact of glycosidic linkages and degree of polymerization on their utilization

Gluco-oligosaccharides (GlcOS) are potential prebiotics that positively modulate beneficial gut commensals like lactobacilli. For the rational design of GlcOS as prebiotics or combined with lactobacilli as synbiotics, it is important to establish the structure requirements of GlcOS and specificity toward lactobacilli. Herein, the utilization of 10 GlcOS with varied degrees of polymerization (DP) and glycosidic linkages by 7 lactobacilli strains (Levilactobacillus brevis ATCC 8287, Limosilactobacillus reuteri ATCC PTA 6475, Lacticaseibacillus rhamnosus ATCC 53103, Lentilactobacillus buchneri ATCC 4005, Limosilactobacillus fermentum FUA 3589, Lactiplantibacillus plantarum WCFS1, and Lactobacillus gasseri ATCC 33323) was studied. L. brevis ATCC 8287 was the only strain that grew on α/β-(1→4/6) linked disaccharides, whereas other strains showed diverse patterns, dependent on the availability of genes encoding sugar transporters and catabolic enzymes. The effect of DP on GlcOS utilization was strain dependent. β-(1→4) Linked cello-oligosaccharides (COS) supported the growth of L. brevis ATCC 8287 and L. plantarum WCFS1, and shorter COS (DP 2-3) were preferentially utilized over longer COS (DP 4-7) (consumption ≥90% vs. 40%-60%). α-(1→4) Linked maltotriose and maltodextrin (DP 2-11) were effectively utilized by L. brevis ATCC 8287, L. reuteri ATCC 6475, and L. plantarum WCFS1, but not L. fermentum FUA 3589. Growth of L. brevis ATCC 8287 on branched isomalto-oligosaccharides (DP 2-6) suggested preferential consumption of DP 2-3, but no preference between α-(1→6) and α-(1→4) linkages. The knowledge of the structure-specific GlcOS utilization by different lactobacilli from this study helps the structural rationale of GlcOS for prebiotic development.

Immobilization of α-transglucosidase on silica-coated magnetic nanoparticles and its application for production of isomaltooligosaccharide from the potato peel

In this study, the production of isomaltooligosaccharide from potato peel starch was carried out in three steps: liquefaction, saccharification, and transglucosylation. Further, cloning α-transglucosidase gene from Aspergillus niger (GH31 family), transforming into E. coli BL21 (DE3), overexpressing and purifying the resulting protein for the production of α-transglucosidase. The generated α-transglucosidase was then bound with magnetic nanoparticles, which improved reusability up to 5 cycles with more than 60% activity. All the modifications were characterized using the following methods: Fourier transform infra-red analysis, Transmission Electron Microscopy, Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, X-Ray Diffraction Spectroscopy, Thermogravimetric Analysis, and Dynamic Light Scattering (DLS) analysis. Further, the optimum conditions for transglucosylation were determined by RSM as follows: enzyme-to-substrate ratio 6.9 U g-1, reaction time 9 h, temperature 45 °C, and pH 5.5 with a yield of 70 g l-1 (± 2.1). MALDI-TOF-MS analysis showed DP of the IMOs in ranges of 2-10. The detailed structural characterization of isomaltooligosaccharide by GC-MS and NMR suggested the α-(1 → 4) and α-(1 → 6)-D-Glcp residues as major constituents along with minor α-(1 → 2) and α-(1 → 3) -D-Glcp residues.

Capsazepine-Induced Altered Colonic Mucosal Health Limits Isomalto-oligosaccharide Action in High-Fat Diet-Fed C57BL/6J Mice

The present study sought to understand the effects of a combination of altered colonic mucosal health (intrarectal capsazepine administration) and high-fat diet (HFD) administration in mice. Furthermore, we also studied whether this combination prevents protective actions of dietary prebiotic, isomaltooligosaccharides. We studied the alterations in intestinal permeability, histological and transcriptional changes, short-chain fatty acid (SCFA) concentrations, and gut microbial abundance. Capsazepine (CPZ) was administered rectally twice a day along with HFD feeding. Following confirmation of CPZ action (loss of TRPA1 and TRPV1-associated nocifensive behavior), the intrarectal dose of CPZ was reduced to once in 2 days up to 8 weeks. Simultaneous intrarectal administration of CPZ exacerbated the HFD (8 weeks feeding)-induced damage to mucosal lining, intestinal permeability, tight junction protein expression, SCFA levels, and gut bacterial abundances. This higher degree of mucosal damage and pathological alteration in colonic mucosa prevented the previously reported protective actions of isomaltooligosaccharides as a prebiotic in HFD-fed mice. Overall, we present evidence that colonic precondition (gut permeability and mucosal lining) is an important factor in determination of HFD-induced changes in the colon, and success of diet-associated interventions (dietary fibers, pre/probiotics, etc.) is dependent on it.

Production of a Series of Long-Chain Isomaltooligosaccharides from Maltose by Bacillus subtilis AP-1 and Associated Prebiotic Properties

Bacillus subtilis strain AP-1, which produces α-glucosidase with transglucosidase activity, was used to produce a series of long-chain isomaltooligosaccharides (IMOs) with degree of polymerization (DP) ranging from 2 to 14 by direct fermentation of maltose. A total IMOs yield of 36.33 g/L without contabacillusmination from glucose and maltose was achieved at 36 h of cultivation using 50 g/L of maltose, with a yield of 72.7%. IMOs were purified by size exclusion chromatography with a Superdex 30 Increase column. The molecular mass and DP of IMOs were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Subsequently, linkages in produced oligosaccharides were verified by enzymatic hydrolysis with α-amylase and oligo-α-1,6-glucosidase. These IMOs showed prebiotic properties, namely tolerance to acidic conditions and digestive enzymes of the gastrointestinal tract, stimulation of probiotic bacteria growth to produce short-chain fatty acids and no stimulating effect on pathogenic bacteria growth. Moreover, these IMOs were not toxic to mammalian cells at up to 5 mg/mL, indicating their biocompatibility. Therefore, this research demonstrated a simple and economical method for producing IMOs with DP2–14 without additional operations; moreover, the excellent prebiotic properties of the IMOs offer great prospects for their application in functional foods.

Recent Research and Application Prospect of Functional Oligosaccharides on Intestinal Disease Treatment

The intestinal tract is an essential digestive organ of the human body, and damage to the intestinal barrier will lead to various diseases. Functional oligosaccharides are carbohydrates with a low degree of polymerization and exhibit beneficial effects on human intestinal health. Laboratory experiments and clinical studies indicate that functional oligosaccharides repair the damaged intestinal tract and maintain intestinal homeostasis by regulating intestinal barrier function, immune response, and intestinal microbial composition. Functional oligosaccharides treat intestinal disease such as inflammatory bowel disease (IBD) and colorectal cancer (CRC) and have excellent prospects for therapeutic application. Here, we present an overview of the recent research into the effects of functional oligosaccharides on intestinal health.

Prebiotic Isomaltooligosaccharide Provides an Advantageous Fitness to the Probiotic Bacillus subtilis CU1

Bacillus subtilis CU1 is a probiotic strain with beneficial effects on immune health in elderly subjects and diarrhea. Commercialized under spore form, new strategies to improve the germination, fitness and beneficial effects of the probiotic once in the gut have to be explored. For this purpose, functional food ingredients, such as isomaltooligosaccharides (IMOSs), could improve the fitness of Bacillus probiotics. IMOSs are composed of α(1 → 6)- and α(1 → 4)-linked oligosaccharides and are partially indigestible. Dietary IMOSs stimulate beneficial members of intestinal microbiota, but the effect of a combination of IMOSs with probiotics, such as B. subtilis CU1, is unknown. In this study, we evaluate the potential effect of IMOSs in B. subtilis CU1 and identify the metabolic pathways involved. The biochemical analysis of the commercial IMOSs highlights a degree of polymerization (DP) comprised between 1 and 29. The metabolism of IMOSs in CU1 was attributed to an α-glucosidase, secreted in the extracellular compartment one hundred times more than with glucose, and which seems to hydrolyze high DP IMOSs into shorter oligosaccharides (DP1, DP2 and DP3) in the culture medium. Proteomic analysis of CU1 after growth on IMOSs showed a reshaping of B. subtilis CU1 metabolism and functions, associated with a decreased production of lactic acid and acetic acid by two times. Moreover, we show for the first time that IMOSs could improve the germination of a Bacillus probiotic in the presence of bile salts in vitro, with an 8 h reduced lag-time when compared to a glucose substrate. Moreover, bacterial concentration (CFU/mL) was increased by about 1 log in IMOS liquid cultures after 48 h when compared to glucose. In conclusion, the use of IMOSs in association with probiotic B. subtilis CU1 in a synbiotic product could improve the fitness and benefits of the probiotic.

The challenges in production technology, health-associated functions, physico-chemical properties and food applications of isomaltooligosaccharides

Isomaltooligosaccharides (IMOs) are recognized as functional food ingredients with prebiotic potential that deliver health benefits. IMOs have attained commercial interest as they are produced from low-cost agricultural products that are widely available and have prospective applications in the food industry. The review examines the various production processes and the main challenges involved in deriving diverse structures of IMO with maximized yield and increased functionality. The different characterization and purification techniques employed for structural elucidation, the physico-chemical importance, technological properties, food-based applications and biological effects (in vitro and in vivo interventions) have been discussed in detail. The key finding is the need for research involving biotechnological and enzymology aspects to simplify the production technologies that meet the industrial and consumer requirements. The knowledge from this article delivers a clear insight to scientists, food technologists and the general public for the improved utilization of IMOs to support the emerging market for functional foods and nutraceuticals.

Synthesis of Isomaltooligosaccharides (IMOs) from Sweet Potato Starch by Simultaneous Saccharification and Transglycosylation Using Saccharomyces cerevisiae Var. diastaticus BE 134 to Improve Purity of IMOs

This study developed a simple two-step procedure to produce isomaltooligosaccharides (IMOs) from low-cost sweet potato starch (SPS). Effect of various reaction parameters on the steps of the synthesis process of IMOs was systematically investigated. The results show that Spezyme Xtra enzyme was the most suitable for the liquefaction step. The oligosaccharide components’ contents, including G1–G10 and G2–G6, reached 73.95 ± 0.02% and 49.24 ± 3.19%, respectively, after liquefaction. The simultaneous saccharification and transglycosylation (SST) reaction of SPS followed the liquefaction after the α-amylase activity was deactivated. This reaction was simultaneously treated by β-amylase, pullulanase, and α-transglucosidase. The effect of various reaction parameters, consisting of solution pH, reaction temperature, enzyme dosage, and reaction time, on the SST reaction to synthesize IMOs from SPS was fully studied. The results showed that the highest concentration of IMOs (IG234) reached 68.85 ± 1.82 g/L at the optimal condition. The purification of pristine IMO was performed by adding Saccharomyces cerevisiae var. diastaticus BE 134 yeast cells at the final step of the procedure. In particular, the SST reaction for the synthesis of IMOs from SPS shortened SST reaction time by three times compared with other three-step synthesis procedures of IMOs. These findings show that the SPS-derived IMOs can be applied as a novel and inexpensive prebiotic healthcare product for human gastrointestinal health, dieters, and diabetics.

Vairimorpha (Nosema) ceranae Infection Alters Honey Bee Microbiota Composition and Sustains the Survival of Adult Honey Bees

Simple Summary

The gut microbiota, in addition to the hosts and the pathogens, has become the third factor involved in gut disease developments, including honey bees. Interestingly, various studies reported positive associations between the gut bacteria and the most commonly found microsporidian pathogen instead of negative associations. To investigate the positive associations, a prebiotic that also exists in honey was added in the trials. Bees fed the prebiotics have slightly higher pathogen counts but lower mortalities. Microbiota analyses suggested that bees with the infection have a microbiota composition similar to that of bees with a longer lifespan, and the prebiotic seemed to enhance the similarities. Since microsporidia typically cause chronic infections, the positive associations may serve to sustain the host lifespans which is the optimal outcome for the pathogen that the survived bees can withstand pathogen proliferation and transmit the pathogens. Although the mechanisms underlying the associations were not revealed, this study indicated that nosema disease management in bees through changes in microbiota may shorten the lifespans or enhance both the infection and the bee population. Such results have appeared in recent field studies. More studies will be needed for the disease management using bee gut microbiota.

Abstract

Vairimorpha (Nosema) ceranae is the most common eukaryotic gut pathogen in honey bees. Infection is typically chronic but may result in mortality. Gut microbiota is a factor that was recently noted for gut infectious disease development. Interestingly, studies identified positive, instead of negative, associations between core bacteria of honey bee microbiota and V. ceranae infection. To investigate the effects of the positive associations, we added isomaltooligosaccharide (IMO), a prebiotic sugar also found in honey, to enhance the positive associations, and we then investigated the infection and the gut microbiota alterations using qPCR and 16S rRNA gene sequencing. We found that infected bees fed IMO had significantly higher V. ceranae spore counts but lower mortalities. In microbiota comparisons, V. ceranae infections alone significantly enhanced the overall microbiota population in the honey bee hindgut and feces; all monitored core bacteria significantly increased in the quantities but not all in the population ratios. The microbiota alterations caused by the infection were enhanced with IMO, and these alterations were similar to the differences found in bees that naturally have longer lifespans. Although our results did not clarify the causations of the positive associations between the infections and microbiota, the associations seemed to sustain the host survival and benefit the pathogen. Enhancing indigenous gut microbe to control nosema disease may result in an increment of bee populations but not the control of the pathogen. This interaction between the pathogen and microbiota potentially enhances disease transmission and avoids the social immune responses that diseased bees die prematurely to curb the disease from spreading within colonies.

Structure-Specific Fermentation of Galacto-Oligosaccharides, Isomalto-Oligosaccharides and Isomalto/Malto-Polysaccharides by Infant Fecal Microbiota and Impact on Dendritic Cell Cytokine Responses

SCOPE

Next to galacto-oligosaccharides (GOS), starch-derived isomalto-oligosaccharide preparation (IMO) and isomalto/malto-polysaccharides (IMMP) could potentially be used as prebiotics in infant formulas. However, it remains largely unknown how the specific molecular structures of these non-digestible carbohydrates (NDCs) impact fermentability and immune responses in infants.

METHODS AND RESULTS

In vitro fermentation of GOS, IMO and IMMP using infant fecal inoculum of 2- and 8-week-old infants shows that only GOS and IMO are fermented by infant fecal microbiota. The degradation of GOS and IMO coincides with an increase in Bifidobacterium and production of acetate and lactate, which is more pronounced with GOS. Individual isomers with an (1↔1)-linkage or di-substituted reducing terminal glucose residue are more resistant to fermentation. GOS, IMO, and IMMP fermentation digesta attenuates cytokine profiles in immature dendritic cells (DCs), but the extent is dependent on the infants age and NDC structure.

CONCLUSION

The IMO preparation, containing reducing and non-reducing isomers, shows similar fermentation patterns as GOS in fecal microbiota of 2-week-old infants. Knowledge obtained on the substrate specificities of infant fecal microbiota and the subsequent regulatory effects of GOS, IMO and IMMP on DC responses might contribute to the design of tailored NDC mixtures for infants of different age groups.

The Athlete and Gut Microbiome: Short-chain Fatty Acids as Potential Ergogenic Aids for Exercise and Training

Short-chain fatty acids (SCFAs) are metabolites produced in the gut via microbial fermentation of dietary fibers referred to as microbiota-accessible carbohydrates (MACs). Acetate, propionate, and butyrate have been observed to regulate host dietary nutrient metabolism, energy balance, and local and systemic immune functions. In vitro and in vivo experiments have shown links between the presence of bacteria-derived SCFAs and host health through the blunting of inflammatory processes, as well as purported protection from the development of illness associated with respiratory infections. This bank of evidence suggests that SCFAs could be beneficial to enhance the athlete's immunity, as well as act to improve exercise recovery via anti-inflammatory activity and to provide additional energy substrates for exercise performance. However, the mechanistic basis and applied evidence for these relationships in humans have yet to be fully established. In this narrative review, we explore the existing knowledge of SCFA synthesis and the functional importance of the gut microbiome composition to induce SCFA production. Further, changes in gut microbiota associated with exercise and various dietary MACs are described. Finally, we provide suggestions for future research and practical applications, including how these metabolites could be manipulated through dietary fiber intake to optimize immunity and energy metabolism.

Bacterial α-diglucoside metabolism: perspectives and potential for biotechnology and biomedicine

In a competitive microbial environment, nutrient acquisition is a major contributor to the survival of any individual bacterial species, and the ability to access uncommon energy sources can provide a fitness advantage. One set of soluble carbohydrates that have attracted increased attention for use in biotechnology and biomedicine is the α-diglucosides. Maltose is the most well-studied member of this class; however, the remaining four less common α-diglucosides (trehalose, kojibiose, nigerose, and isomaltose) are increasingly used in processed food and fermented beverages. The consumption of trehalose has recently been shown to be a contributing factor in gut microbiome disease as certain pathogens are using α-diglucosides to outcompete native gut flora. Kojibiose and nigerose have also been examined as potential prebiotics and alternative sweeteners for a variety of foods. Compared to the study of maltose metabolism, our understanding of the synthesis and degradation of uncommon α-diglucosides is lacking, and several fundamental questions remain unanswered, particularly with regard to the regulation of bacterial metabolism for α-diglucosides. Therefore, this minireview attempts to provide a focused analysis of uncommon α-diglucoside metabolism in bacteria and suggests some future directions for this research area that could potentially accelerate biotechnology and biomedicine developments. KEY POINTS: • α-diglucosides are increasingly important but understudied bacterial metabolites. • Kinetically superior α-diglucoside enzymes require few amino acid substitutions. • In vivo studies are required to realize the biotechnology potential of α-diglucosides.

Effects of Dietary Isomaltooligosaccharide Levels on the Gut Microbiota, Immune Function of Sows, and the Diarrhea Rate of Their Offspring

To investigate the effects of dietary isomaltooligosaccharide (IMO) levels on the gut microbiota, immune function of sows, and the diarrhea rate of their offspring, 120 multiparous gestating pig improvement company (PIC) sows with similar body conditions were selected and fed 1 of 6 diets: a basal diet with no supplement (control, CON), or a diet supplemented with 2.5 g/kg, 5.0 g/kg, 10.0 g/kg, 20.0 g/kg, or 40.0 g/kg IMO (IMO1, IMO2, IMO3, IMO4, or IMO5 group, respectively). Results showed that dietary treatments did not affect the reproductive performance and colostrum composition of sows (P > 0.05). However, compared to the CON, IMO reduced the diarrhea rate of suckling piglets (P < 0.05) and improved the concentrations of colostrum IgA, IgG, and IgM (P < 0.05). Moreover, IMO decreased the concentrations of serum D-lactate (D-LA) and lipopolysaccharides (LPS) at farrowing and day 18 of lactation (L18) (P < 0.05). High-throughput pyrosequencing of the 16S rRNA demonstrated that IMO shaped the composition of gut microbiota in different reproductive stages (day 107 of gestation, G107; day 10 of lactation, L10) (P < 0.05). At the genus level, the relative abundance of g_Parabacteroides and g_Slackia in G107 and g_Unclassified_Peptostreptococcaceae, g_Turicibacter, g_Sarcina, and g_Coprococcus in L10 was increased in IMO groups but the g_YRC22 in G107 was decreased in IMO groups relative to the CON group (P < 0.05). Furthermore, the serum D-LA and LPS were negatively correlated with the genus g_Akkermansia and g_Parabacteroides but positively correlated with the genus g_YRC22 and g_Unclassified_Peptostreptococcaceae. Additionally, the colostrum IgA, IgG, and IgM of sows were positively correlated with the genus g_Parabacteroides, g_Sarcina, and g_Coprococcus but negatively correlated with the genus g_YRC22. These findings indicated that IMO could promote the immune activation and had a significant influence in sows' gut microbiota during perinatal period, which may reduce the diarrhea rate of their offspring.

Digestibility of branched and linear α-gluco-oligosaccharides in vitro and in ileal-cannulated pigs

Isomalto-oligosaccharides (IMOs) may promote health by modulating intestinal microbiota. We hypothesized that the proportion of α-(1 → 6) linkages in IMOs determines their digestibility. Ileal-cannulated pigs were fed diets containing IMO, IMO-DP3 with a greater DP and more α-(1 → 4) linkages, and digestible or resistant maltodextrins. Oligosaccharides were analysed by high-performance anion-exchange chromatography. Compared to IMO, IMO-DP3 contained more panose (18.6 vs. 10.3%) but less isomaltose (7.5 vs. 22.3%) and isomaltotriose (6.1 vs. 12.6%). The apparent ileal digestibility of dry matter were 3% greater for IMO-DP3 and digestible maltodextrin than resistant maltodextrin; the digestibility of IMO was not different from other oligosaccharides. Ileal propionate, isovalerate, and total SCFA was greater for IMO-DP3 and digestible maltodextrin than IMO. In conclusion, IMO was less digestible than IMO-DP3. Structural properties of IMOs are important determinants of their functional properties within the porcine digestive tract.

Analysis of Targeted Metabolites and Molecular Structure of Starch to Understand the Effect of Glutinous Rice Paste on Kimchi Fermentation

Bachu (Chinese cabbage) kimchi, a Korean traditional fermented dish, were prepared with or without the addition of glutinous (waxy) rice paste and their characteristics including pH, total bacteria count, total starch content, sugar metabolites, and molecular structure of starch were examined periodically for 20 days to investigate the effect of adding glutinous rice paste to kimchi during fermentation. The pH and total bacteria count showed that the fermentation of kimchi added with glutinous rice paste (GRP kimchi) progressed a little more quickly than that of control kimchi without glutinous rice paste. The GRP kimchi had higher glucose content but lower fructose content than control kimchi. Interestingly, maltose was only detected in GRP kimchi during fermentation. The GRP kimchi contained much greater amount of mannitol throughout fermentation than control kimchi. Total starch content in GRP kimchi gradually decreased during fermentation, which might have contributed to its greater glucose content and the larger amount of maltose production. In GRP kimchi, peak height and area for all degrees of polymerization (DP) of starch decreased during fermentation and its average chain length decreased while the proportion of short chains increased as fermentation processed, indicating degradation of starch chains by enzymes presented in the kimchi.

Site Directed Mutagenesis of Dextransucrase DsrM from Weissella cibaria: Transformation to a Reuteransucrase

Glucansucrases produce α-glucans and gluco-oligosaccharides; the linkage type and molecular weight of glucans impacts their functionality. This study compared the catalytic specificities of dextransucrase DsrM from Weissella cibaria 10M and derivatives of this enzymes with GtfA from Lactobacillus reuteri TMW1.656. The N-variable region, which is dispensable for GtfA activity, was essential for DsrM activity. Parallel amino acid substitutions in DsrM-ΔS and GtfA-ΔN indicated that the acceptor binding site residues determining the linkage type differ in these enzymes. DsrM-V583P:V586I had comparable enzyme activity as the respective GtfA derivative but did not increase the proportion of α-(1→4) linkages. DsrM-S622N had low enzyme activity and an unaltered proportion of α-(1→4) linkages while the analogous GtfA-S1062N maintained enzyme activity but increased the proportion of α-(1→4) linkages. This study of dextransucrase from Weissella spp. thus elucidated differences between glucansucrases and will facilitate study of the structure-function relationships of dextran and isomalto-oligosaccharides.

Optimization of Isomaltooligosaccharide Size Distribution by Acceptor Reaction of Weissella confusa Dextransucrase and Characterization of Novel α-(1→2)-Branched Isomaltooligosaccharides

Long-chain isomaltooligosaccharides (IMOs) are promising prebiotics. IMOs were produced by a Weissella confusa dextransucrase via maltose acceptor reaction. The inputs of substrates (i.e., sucrose and maltose, 0.15-1 M) and dextransucrase (1-10 U/g sucrose) were used to control IMO yield and profile. According to response surface modeling, 1 M sucrose and 0.5 M maltose were optimal for the synthesis of longer IMOs, whereas the dextransucrase dosage showed no significant effect. In addition to the principal linear IMOs, a homologous series of minor IMOs were also produced from maltose. As identified by MS(n) and NMR spectroscopy, the minor trisaccharide contained an α-(1→2)-linked glucosyl residue on the reducing residue of maltose and thus was α-d-glucopyranosyl-(1→2)-[α-d-glucopyranosyl-(1→4)]-d-glucopyranose (centose). The higher members of the series were probably formed by the attachment of a single unit branch to linear IMOs. This is the first report of such α-(1→2)-branched IMOs produced from maltose by a dextransucrase.

A novel cobiotic-based preventive approach against high-fat diet-induced adiposity, nonalcoholic fatty liver and gut derangement in mice

BACKGROUND

High-fat diets (HFDs) induce systemic inflammation, gut microbial derangements and disturb metabolic homeostasis, resulting in weight gain, insulin resistance and nonalcoholic fatty liver (NAFL). Numerous antioxidants and prebiotic/probiotics per se may prevent HFD-associated comorbidities, but there are no reports related to their combination.

OBJECTIVE

In the present study, we aim to evaluate a cobiotic combination of lycopene (antioxidant) and isomalto-oligosaccharides (IMOs, a prebiotic) for prevention of HFD-induced alterations.

DESIGN

Male Swiss albino mice were fed either normal pellet diet (NPD) or HFD and lycopene (5 and 10 mg kg(-1)), IMOs (0.5 and 1 g kg(-1)) or their combination for 12 weeks. Systemic adiposity, glucose tolerance, insulin sensitivity, feeding regulators in hypothalamus, hepatosteatosis and liver inflammation, cecal short chain fatty acids (SCFAs), serum inflammatory cytokines, gut morphology and alterations in selected gut microbes were studied.

RESULTS

Lycopene, IMOs and their combination prevented weight gain, adiposity, improved adipose tissue fat mobilization and reduced insulin resistance. Hypothalamic orexigenic and anorectic genes have also been modulated by these treatments. Dietary interventions prevented NAFL-like symptoms and improved glucose homeostasis. Improvement in selected gut microbial abundance and SCFA concentration along with reduced systemic inflammation, metabolic endotoxemia and improved ileal and colonic health were observed in mice supplemented with lycopene, IMOs and their combination. Interestingly, cobiotic combination synergistically improved many of the HFD-induced alterations.

CONCLUSION

The present work provide evidence that new approach based on cobiotic combination (antioxidant plus prebiotic) can be employed to develop novel class of functional foods for their application against HFD-associated pathological complications.

Chemically defined diet alters the protective properties of fructo-oligosaccharides and isomalto-oligosaccharides in HLA-B27 transgenic rats

Non-digestible oligosaccharides (NDO) were shown to reduce inflammation in experimental colitis, but it remains unclear whether microbiota changes mediate their colitis-modulating effects. This study assessed intestinal microbiota and intestinal inflammation after feeding chemically defined AIN-76A or rat chow diets, with or without supplementation with 8 g/kg body weight of fructo-oligosaccharides (FOS) or isomalto-oligosaccharides (IMO). The study used HLA-B27 transgenic rats, a validated model of inflammatory bowel disease (IBD), in a factorial design with 6 treatment groups. Intestinal inflammation and intestinal microbiota were analysed after 12 weeks of treatment. FOS and IMO reduced colitis in animals fed rat chow, but exhibited no anti-inflammatory effect when added to AIN-76A diets. Both NDO induced specific but divergent microbiota changes. Bifidobacteria and Enterobacteriaceae were stimulated by FOS, whereas copy numbers of Clostridium cluster IV were decreased. In addition, higher concentrations of total short-chain fatty acids (SCFA) were observed in cecal contents of rats on rat chow compared to the chemically defined diet. AIN-76A increased the relative proportions of propionate, iso-butyrate, valerate and iso-valerate irrespective of the oligosaccharide treatment. The SCFA composition, particularly the relative concentration of iso-butyrate, valerate and iso-valerate, was associated (P ≤ 0.004 and r ≥ 0.4) with increased colitis and IL-1 β concentration of the cecal mucosa. This study demonstrated that the protective effects of fibres on colitis development depend on the diet. Although diets modified specific cecal microbiota, our study indicates that these changes were not associated with colitis reduction. Intestinal inflammation was positively correlated to protein fermentation and negatively correlated with carbohydrate fermentation in the large intestine.