Prebiotic Galacto-oligosaccharides Research Articles

Effect of glucose depletion during the synthesis of galactooligosaccharides using a trienzymatic system

In this study the effect of glucose depletion using glucose oxidase and catalase, simultaneously to the synthesis of prebiotic galactooligosaccharides (GOS) by β-galactosidase was studied. Considering total GOS yield, a strong dependency on the source of β-galactosidase was found. Using an Aspergillus oryzae lactase, a small increase in GOS yield (from 50.0 ± 1.3 g/L to 54.1 ± 1.9 g/L) was noted. Due to the decreased rate of GOS disaccharide formation by the Kluyveromyces lactis enzyme, the total GOS yield was diminished (from 47.4 ± 0.1 g/L to 30.5 ± 1.7 g/L). However, for both enzymes, the synthesis of GOS tri- and higher oligosaccharides increased. Additionally, the total sugar content, and thus caloric value, of the final product was reduced, also resulting in a more purified GOS mixture.

Combination of two β-galactosidases during the synthesis of galactooligosaccharides may enhance yield and structural diversity

In this study, the combination of two β-galactosidases to synthesize prebiotic galactooligosaccharides (GOS) was evaluated in terms of total GOS yield as well as GOS structures (chain length). Two different combinations of either Aspergillus oryzae and Cryptococcus laurentii or Aspergillus oryzae and Kluyveromyces lactis were tested to examine the influence of enzyme origin. Neither consecutive nor simultaneous synthesis with A. oryzae and C. laurentii led to an increased GOS yield. However, with the latter, synthesis of higher GOS (≥3 monomer units) was enhanced from 38.5% to 40% with special emphasis of tetra- and pentasaccharides, which increased from 6.7% to 12.8% and from 0.4% to 3.3%, respectively. Additionally, due to the different preferences of the two β-galactosidases in terms of types of glycosidic linkages, the structural diversity of the final GOS product could be increased. Using K. lactis following the synthesis with A. oryzae increased the yield of total GOS from 24.6% to 33.1%, which was mainly due to the formation of GOS disaccharides. On the other hand, applying A. oryzae as the second enzyme led to a degradation of di- and trisaccharides, and thus total GOS yield was diminished, although the yield of tetrasaccharides could be enhanced. In conclusion, with both studied enzyme combinations it was possible to increase the percentage of higher GOS and reduce the residual lactose content of the final mixture, which is beneficial for subsequent purification processes. Thus, using more than one β-galactosidase during the synthesis of GOS represents an interesting research area, which should be explored in more detail in the future.

Synthesis of prebiotic galactooligosaccharides from lactose and lactulose by dairy propionibacteria

The potential of probiotic bacteria to produce prebiotic oligosaccharides by transgalactosylation has been minimally studied. In this work, we screened the β-galactosidase (β-gal) activity of dairy propionibacteria (PAB) isolated from Argentinean foods to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu). PAB, when grown in a medium with lactose as a carbon source, were disrupted, and the cell-free extracts were assayed for β-gal activity. Nine strains grew on lactose and showed β-gal activities from 0.27 to 2.60 U mL−1. Propionibacterium acidipropionici LET 120, the strain with the highest activity, was able to synthesize, using 30% lactose and lactulose at pH 6.5 and 45 °C, 26.8% of LET 120-GOS and 26.1% of LET 120-OsLu after 24 h. When they were tested as carbon sources for growth, P. acidipropionici LET 120 attained higher biomasses, μmax and β-gal activities at the expense of Aspergillus oryzae-OsLu, Vivinal®-GOS and lactulose compared to lactose or glucose. In addition, LET 120-GOS and LET 120-OsLu synthesized by PAB were prebiotic for some probiotic strains. For the first time, our results show the production of GOS and OsLu by dairy PAB, and these results encourage further studies on the optimization of the synthesis and structure characterization of the obtained oligosaccharides.

Effect of a prebiotic galactooligosaccharide mixture (B-GOS®) on gastrointestinal symptoms in adults selected from a general population who suffer with bloating, abdominal pain, or flatulence.

Prebiotics exert beneficial effects upon gastrointestinal (GI) environment, but this is not always accompanied with a positive effect on GI symptoms. B-GOS® is a prebiotic with high selectivity toward bifidobacteria and a variety of other beneficial effects in humans. Here, we investigated its effect on GI symptoms in adults who suffer with bloating, abdominal pain, and flatulence. In a double-blind, placebo-controlled, crossover study, 83 subjects from the general population who presented with GI symptoms during screening period and had a predicted probability of functional bowel disorder of more than 75% were randomized to receive either a placebo or the B-GOS® treatment (2.75g/d). Subjects were screened for the presence of GI symptoms for 1 week, they consumed the treatments for 2 weeks, and then went through a 2-week washout period, before switching to the other treatment for the final 2 weeks. GI symptoms, bowel movements, and stool consistency were assessed in daily and weekly questionnaires. Quality of life was assessed weekly and depression and anxiety at the end of each treatment period. B-GOS® resulted in significantly (P<0.001) lower scores for bloating, flatulence, and abdominal pain both from baseline and placebo at the end of first week. The effect was sustained at the end of second week. It had no effect on the number of bowel movements, consistency of stools, quality of life, or mood throughout the study. Results suggest that B-GOS® could possibly be used in the management of bloating, flatulence, or abdominal pain and warrant further investigation.

Effect of purification of galactooligosaccharides derived from lactulose with Saccharomyces cerevisiae on their capacity to bind immune cell receptor Dectin-2

Lactulose-derived oligosaccharides (OsLu) are prebiotic galactooligosaccharides (GOS) beneficial for human health including immunomodulatory properties; however, the molecular mechanism is unclear. OsLu produced by enzymatic synthesis can be purified with Saccharomyces cerevisiae (OsLu-Sc). We show that this purification introduces yeast-derived proteins reactive to Dectin-2, an innate immune receptor for fungal polysaccharides. Using a cell-based bioassay, we tested the binding of OsLu and GOS samples to Dectin-2. While OsLu purified with active charcoal and commercial GOS failed to bind to Dectin-2, we found OsLu-Sc bound to this receptor. The carbohydrate-binding incompetent mutant of Dectin-2 failed to bind to OsLu-Sc. These data suggest that OsLu-Sc introduced carbohydrate ligands for Dectin-2. In accordance with this, proteomic analysis revealed OsLu-Sc contained S. cerevisiae-derived mannoproteins. Therefore, our data highlight the importance of the purification method for OsLu, which may positively affect the bioactivity of OsLu. Data are available via ProteomeXchange with identifier PXD010495.

Functional Characterization of a New Cold-Adapted β-Galactosidase from an Arctic Fjord Sediment Bacteria Enterobacter ludwigii MCC 3423

In the present study, a new cold-adapted β-galactosidase, BgalEL isolated from the fjord sediment bacteria, Enterobacter ludwigii MCC 3423, was purified and characterized. The phylogenetic analysis of partial sequence of bgalEL gene revealed 99% relatedness of the enzyme to Enterobacter cloacae β-galactosidase. BgalEL is a homotetramer with molecular weight 465 kDa composed of ~ 116.42 kDa subunits. The optimal pH range and temperature for maximum hydrolytic activity on ONPG were 7.0–8.0 and 45 °C respectively. BgalEL was stable at pH ranges 6.0–8.0. The Km and Vmax for BgalEL were recorded as 2.03 mM and 49.3 U mg−1 respectively. The product formation by BgalEL was modelled with various degradation kinetic models and zeroth was found as model was best-fitted model. The kinetic half-life period of ONPG was noted as 9.0 × 10−4. The presence of K+, Mg2+ and Mn2+ at 10 mM concentrations stimulated BgalEL activity by 31 ± 3.9, 34 ± 1.2 and 42 ± 1.9% respectively. It was interesting to see that BgalEL was least affected by the hydrolytic products, glucose and galactose. Noteworthy, effect of Ca2+ ions on BgalEL activity was negligible at concentrations of 10 mM. BgalEL hydrolyzed lactose in milk at refrigerated temperature and also displayed transglycosylation potential in the presence of substantial concentrations of lactose at 40 °C. Finally, this is the first report with such a detailed characterization of β-galactosidase enzyme from a gram-negative bacterium isolated from the Arctic region. In light of the above mentioned properties, we thus recommend the enzyme BgalEL for the large scale production lactose free milk for the safe consumption in lactose-intolerance and the prebiotic galactooligosaccharides as supplement for infant food formulas.

The oligosaccharides 6'-sialyllactose, 2'-fucosyllactose or galactooligosaccharides do not directly modulate human dendritic cell differentiation or maturation.

Breast milk plays an important role in immune development in early life and protects against diseases later in life. A wide range of the beneficial effects of breast milk are attributed to human milk oligosaccharides (HMOs) as well as components such as vitamin D3 (VitD3) or TGFβ. One mechanism by which HMOs might contribute to immune homeostasis and protection against disease is the induction of a local tolerogenic milieu. In this study we investigated the effect of the HMOs 6’-sialyllactose (6’SL) and 2’-fucosyllactose (2’FL) as well as prebiotic galactooligosaccharides (GOS) on DC differentiation and maturation. Isolated CD14+ monocytes were cultured for six days in the presence of GM-CSF and IL-4 with or without 6’SL, 2’FL, GOS, VitD3 or TGFβ. Additionally, immature VitD3DC, TGFβDC and moDC were used as different DC types to investigate the effect of 6’SL, 2’FL and GOS on DC maturation. Surface marker expression and cytokine production was measured by flow cytometry and cytometric bead array, respectively. Unlike TGFβ and vitD3, the oligosaccharides 6’SL, 2’FL and GOS did not influence DC differentiation. Next, we studied the effect of 6’SL, 2’FL and GOS on maturation of moDC, VitD3DC and TGFβDC that showed different profiles of HMO-binding receptors. 6’SL, 2’FL and GOS did not modulate LPS-induced maturation, even though their putative receptors were present on the different DCs types. Thus, whereas VitD3 and TGFβ halt DC differentiation, which results in phenotypically distinct tolerogenic DCs, 6’SL, 2’FL and GOS do not alter DC differentiation or maturation of in vitro differentiated DC types.

Probiotic Bifidobacterium strains and galactooligosaccharides improve intestinal barrier function in obese adults but show no synergism when used together as synbiotics

BackgroundOne way to improve both the ecological performance and functionality of probiotic bacteria is by combining them with a prebiotic in the form of a synbiotic. However, the degree to which such synbiotic formulations improve probiotic strain functionality in humans has not been tested systematically. Our goal was to use a randomized, double-blind, placebo-controlled, parallel-arm clinical trial in obese humans to compare the ecological and physiological impact of the prebiotic galactooligosaccharides (GOS) and the probiotic strains Bifidobacterium adolescentis IVS-1 (autochthonous and selected via in vivo selection) and Bifidobacterium lactis BB-12 (commercial probiotic allochthonous to the human gut) when used on their own or as synbiotic combinations. After 3 weeks of consumption, strain-specific quantitative real-time PCR and 16S rRNA gene sequencing were performed on fecal samples to assess changes in the microbiota. Intestinal permeability was determined by measuring sugar recovery in urine by GC after consumption of a sugar mixture. Serum-based endotoxin exposure was also assessed.ResultsIVS-1 reached significantly higher cell numbers in fecal samples than BB-12 (P < 0.01) and, remarkably, its administration induced an increase in total bifidobacteria that was comparable to that of GOS. Although GOS showed a clear bifidogenic effect on the resident gut microbiota, both probiotic strains showed only a non-significant trend of higher fecal cell numbers when administered with GOS. Post-aspirin sucralose:lactulose ratios were reduced in groups IVS-1 (P = 0.050), IVS-1 + GOS (P = 0.022), and GOS (P = 0.010), while sucralose excretion was reduced with BB-12 (P = 0.002) and GOS (P = 0.020), indicating improvements in colonic permeability but no synergistic effects. No changes in markers of endotoxemia were observed.ConclusionThis study demonstrated that “autochthony” of the probiotic strain has a larger effect on ecological performance than the provision of a prebiotic substrate, likely due to competitive interactions with members of the resident microbiota. Although the synbiotic combinations tested in this study did not demonstrate functional synergism, our findings clearly showed that the pro- and prebiotic components by themselves improved markers of colonic permeability, providing a rational for their use in pathologies with an underlying leakiness of the gut.

Microbial diversity and health-promoting properties of the traditional Bulgarian yogurt

ABSTRACTBulgarian yogurt is usually associated with good health and longevity. This study aimed to analyse the current microbial content of homemade Bulgarian yogurt. Identification by 16S rDNA sequencing revealed that out of 76 isolated strains, 53% belonged to Lactobacillus delbrueckii subsp. bulgaricus, 14% to other lactobacilli, and 32% to lactic acid cocci (Streptococcus thermophilus, Pediococcus acidilactici, Enterococcus faecium and Leuconostoc). All isolates inhibited the growth of pathogenic bacteria (10% of them by the putative action of bacteriocins); 18 isolates were able to produce extracellular exopolysaccharides (EPS), whereas 24% of them demonstrated extremely high proteolytic activity. Remarkably, 10 Lb. bulgaricus strains produced prebiotic galactooligosaccharides (GOS). High-resolution accurate mass spectrometry (HRAMS) analysis revealed production of tri- and tetrasaccharides containing atypical β(1→4) glycosidic bonds, reported for the first time for Lb. bulgaricus. Based on the beneficial features, along with good technological behaviour, we recommend several isolates as highly promising for Bulgarian yogurt starters.

Unlocking gut health with the prebiotic galactooligosaccharide (GOS) and probiotic L. reuteri to keep pathogenic S. typhimurium at bay

The microbiome is a dynamic community that can positively and negatively influence host health. Lactobacillus reuteri is a probiotic that has received much attention for its ability to inhibit pathogens such as Salmonella typhimurium, Escherichia coli, and Clostridium difficile. It does so by its unique ability to metabolize glycerol into the antimicrobial compound 3‐HPA, which is commonly referred to as reuterin. The ability to secrete reuterin is dependent not only on glycerol availability but also the concentration of glucose. In fact, there appears to be a “goldilocks” ratio between glucose and glycerol as either too much or too little glucose significantly diminishes reuterin production. Since L. reuteri primarily resides in distal regions of the intestine and colon where most of the glucose has already been absorbed, it seems unlikely that reuterin production would be promoted at the physiological level via this mechanism.Prebiotics are carbohydrates that are indigestible by the host and remain for enzymatic digestion by intestinal probiotics. Inulin and galactooligosaccharides (GOS) are two widely studied prebiotics that are known for their ability to promote the growth of a wide range of lactobacilli, and have been shown to promote L. reuteri growth to varying degrees. Here, we asked if prebiotics such as inulin and GOS promote the production of reuterin in the absence of glucose. L. reuteri were cultured in TSB with or without glycerol in the presence of either glucose, inulin, or GOS, and assessed for their ability to produce reuterin. While inulin did not enhance the production of reuterin, GOS induced reuterin production, although 45% less than that of glucose. Moreover, unlike the dose‐dependence observed with glucose, incubation with GOS induced similar reuterin production regardless of concentration. This suggests that an enzymatic equilibrium may exist where glucose/galactose is cleaved from GOS only as needed by L. reuteri. Finally, to confirm the biopotency of reuterin production, we cultured S. typhimurium with supernatants from L. reuteri that were grown with various carbohydrates. Supernatant dilutions as low as 1:15 were able to significantly retard growth of S. typhimurium with ratios of 1:1 completely inhibiting growth. Together, these results suggest that prebiotics such as GOS may be able to elicit physiologically relevant production of reuterin, which may shape the flora of the microbiome and reduce incidence and severity of pathological infections. Further, as GOS are particularly abundant in breast milk, it suggests a possible link for early immunoprotection from intestinal pathogens while the infant is still immunologically naïve.Support or Funding InformationOlivet Nazarene University Honors Program and Department of Biological SciencesThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

An Attenuated Salmonella enterica Serovar Typhimurium Strain and Galacto-Oligosaccharides Accelerate Clearance of Salmonella Infections in Poultry through Modifications to the Gut Microbiome.

Salmonella is estimated to cause one million foodborne illnesses in the United States every year. Salmonella-contaminated poultry products are one of the major sources of salmonellosis. Given the critical role of the gut microbiota in Salmonella transmission, a manipulation of the chicken intestinal microenvironment could prevent animal colonization by the pathogen. In Salmonella, the global regulator gene fnr (fumarate nitrate reduction) regulates anaerobic metabolism and is essential for adapting to the gut environment. This study tested the hypothesis that an attenuated Fnr mutant of Salmonella enterica serovar Typhimurium (attST) or prebiotic galacto-oligosaccharides (GOS) could improve resistance to wild-type Salmonella via modifications to the structure of the chicken gut microbiome. Intestinal samples from a total of 273 animals were collected weekly for 9 weeks to evaluate the impact of attST or prebiotic supplementation on microbial species of the cecum, duodenum, jejunum, and ileum. We next analyzed changes to the gut microbiome induced by challenging the animals with a wild-type Salmonella serovar 4,[5],12:r:- (Nalr) strain and determined the clearance rate of the virulent strain in the treated and control groups. Both GOS and the attenuated Salmonella strain modified the gut microbiome but elicited alterations of different taxonomic groups. The attST produced significant increases of Alistipes and undefined Lactobacillus, while GOS increased Christensenellaceae and Lactobacillus reuteri The microbiome structural changes induced by both treatments resulted in a faster clearance after a Salmonella challenge.IMPORTANCE With an average annual incidence of 13.1 cases/100,000 individuals, salmonellosis has been deemed a nationally notifiable condition in the United States by the Centers for Disease Control and Prevention (CDC). Earlier studies demonstrated that Salmonella is transmitted by a subset of animals (supershedders). The supershedder phenotype can be induced by antibiotics, ascertaining an essential role for the gut microbiota in Salmonella transmission. Consequently, modulation of the gut microbiota and modification of the intestinal microenvironment could assist in preventing animal colonization by the pathogen. Our study demonstrated that a manipulation of the chicken gut microbiota by the administration of an attenuated Salmonella strain or prebiotic galacto-oligosaccharides (GOS) can promote resistance to Salmonella colonization via increases of beneficial microorganisms that translate into a less hospitable gut microenvironment.

Enzymatic conversion of milk lactose to prebiotic galacto-oligosaccharides to produce low lactose yogurt

Prebiotic yogurt (PY) with improved galacto-oligosaccharides (GalOS) was produced through transgalactosylation of lactose followed by physico-chemical and organoleptic evaluation. The chemical composition of fresh and prebiotic milk was statistically (p > .05) similar except for lactose which was reduced from 4.8% in control milk to 1.9% in prebiotic milk. Lactose in PY (1.44 ± 0.01%) was statistically reduced as compared to control yogurt (3.4 ± 0.02%), while other parameters, that is, fat, protein, pH, and acidity were statistically similar. Lactose (60%) was bio-converted producing 0.9 g GalOS, 0.9 g glucose and 0.55 g galactose per 100 g of PY as determined by assay kits and HPLC. The organoleptic evaluation for color, consistency, and overall acceptability was statistically similar for both yogurts while taste and syneresis were improved in PY due to newly produced monosaccharides and GalOS, respectively. It can be concluded that transgalactosylation of milk lactose improves acceptability of PY and is important for lactose intolerant individuals. Practical applications Lactose intolerance is a serious issue around the globe and it is highly required to produce low lactose or lactose free dairy products. In the present study, major part of milk lactose has been converted to prebiotic galacto-oligosaccharides using beta-galactosidase and the prebiotic milk has been used to produce yogurt with significantly reduced lactose. This process is very much required in dairy industry to produce novel dairy products with reduced lactose.

Application of a commercial digestive supplement formulated with enzymes and probiotics in lactase non-persistence management.

Strategies to avoid lactose malabsorption, which affects 70% of the world's population, are focused on the restriction of milk and dairy products or the use of non-human β-galactosidases or probiotics endowed with β-galactosidase activity added at mealtime. Our evaluation of a commercial blend of probiotics and enzymes (protease, lactase, lipase and amylase) and its potential application in lactase non-persistence management is described in this work. Recommended amounts (460-1000 mg) of the commercial probiotics-enzyme blend were shown to be adequate for performing in vitro lactose hydrolysis in standard solutions (0.25-5%) and commercial dairy products, namely milks (5% lactose) and yogurts (3% lactose), reaching hydrolysis values between 44 and 96%. According to these percentages, the use of the enzymatic preparation would guarantee the intake of less than 12 g, the recommendation of the EFSA for lactose intolerance. Furthermore, formation of prebiotic galactooligosaccharides was also detected, increasing the potential benefits of the enzymatic preparation in the gastrointestinal system.

Efficacy and Enzymatic Synthesis of Prebiotic Galacto-Oligosaccharides from Lactose Against Colon Carcinogenesis in Male Rats

Efficacy and Enzymatic Synthesis of Prebiotic Galacto-Oligosaccharides from Lactose Against Colon Carcinogenesis in Male Rats

Synthesis, kinetic analysis and modelling of galacto-oligosaccharides formation

To design and optimize chemical reactors and bio reactors a profound understanding of kinetics and in particular suitable mechanistic rate models is needed. In chemical reaction engineering the methodology from Christiansen considering elementary kinetics assuming rate-determining steps has been successfully applied. It is hardly considered for enzymatic reactions. In this work, kinetics of formation of the prebiotics galacto-oligosaccharides (GOS) from lactose were investigated with β-galactosidase using batch and dynamic experiments. The rates of the main and most relevant side reactions were quantified. Preliminary investigations were performed to determine the influence of pH, temperature, the amount of enzyme and the initial lactose concentration. To acquire mechanistic understanding instructive perturbation experiments were carried out dosing the substrate lactose and/or the products galactose and glucose either initially or dynamically during fermentation. Based on a postulated catalytic cycle, mechanistic kinetic models were developed considering hydrolysis of lactose, formation of GOS and inhibiting effects of the side products glucose and galactose. A sensitivity analysis was performed applying the subset selection method including model reduction based on singular value decomposition combined with rank revealing QR factorization. The parameterized mechanistic models allowed a good description of batch and dynamic experiments in a broad range of operating conditions.

Impact of Dietary Galacto-Oligosaccharide (GOS) on Chicken's Gut Microbiota, Mucosal Gene Expression, and Salmonella Colonization.

Preventing Salmonella colonization in young birds is key to reducing contamination of poultry products for human consumption (eggs and meat). While several Salmonella vaccines have been developed that are capable of yielding high systemic antibodies, it is not clear how effective these approaches are at controlling or preventing Salmonella colonization of the intestinal tract. Effective alternative control strategies are needed to help supplement the bird’s ability to prevent Salmonella colonization, specifically by making the cecum less hospitable to Salmonella. In this study, we investigated the effect of the prebiotic galacto-oligosaccharide (GOS) on the cecal microbiome and ultimately the carriage of Salmonella. Day-old pullet chicks were fed control diets or diets supplemented with GOS (1% w/w) and then challenged with a cocktail of Salmonella Typhimurium and Salmonella Enteritidis. Changes in cecal tonsil gene expression, cecal microbiome, and levels of cecal and extraintestinal Salmonella were assessed at 1, 4, 7, 12, and 27 days post infection. While the Salmonella counts were generally lower in the GOS-treated birds, the differences were not significantly different at the end of the experiment. However, these data demonstrated that treatment with the prebiotic GOS can modify both cecal tonsil gene expression and the cecal microbiome, suggesting that this type of treatment may be useful as a tool for altering the carriage of Salmonella in poultry.

Effects of dietary supplementation with Pediococcus acidilactici MA18/5M, galactooligosaccharide and their synbiotic on growth, innate immunity and disease resistance of rockfish (Sebastes schlegeli)

The trial investigated the effects of dietary supplementation with the commercial prebiotic galactooligosaccharide (1% GOS; GOS diet), the commercial probiotic Pediococcus acidilactici MA18/5M (6.3 log CFU g−1 PA; PA diet) and their combination as synbiotic (1% GOS and 6.3 log CFU g−1 PA; SYN diet) on the growth, innate immunity and disease resistance of juvenile rockfish (Sebastes schlegeli). Triplicate groups of fish (18.2±0.3g) were fed one of the four diets for 8weeks and then subjected to a standard challenge with Edwardsiella tarda by intraperitoneal injection. The results showed significant (P<0.05) improvement in growth performance in the SYN compared to the control group with intermediary benefits for PA and GOS. White blood cells count was significantly enhanced in the PA and GOS groups with a further significant increase for the SYN diet. In accordance and compared to the control; serum lysozyme and bacteriostatic activities against Vibrio anguillarum and Escherichia coli were increased in all supplemented groups while serum alternative complement activity was elevated in the SYN group. In addition, the skin mucus bacteriostatic activities were significantly influenced by dietary treatments. The beneficial effects observed on circulating innate immune parameters were validated by a higher survival pattern following intraperitoneal challenge with E. tarda in the PA and SYN groups. This study contributes to the knowledge on the mode of action of GOS and PA and demonstrates their potential as natural health and growth promoters in the rockfish on-growing aquaculture industry.

Impact of Novel Prebiotic Galacto-Oligosaccharides on Various Biomarkers of Colorectal Cancer in Wister Rats.

Colorectal cancer (CRC) is one of the leading causes of cancer deaths around the globe. Bioactive food ingredients such as prebiotics have protective potential in colon cancer. Data on galacto-oligosaccharides (GalOS) against CRC are very limited and GalOS used in this study have β-1,6 and β-1,3 as major glycosidic linkages and, to our best knowledge, were never used before against any cancer treatment. This study aims to investigate the protective role of novel GalOS against various biomarkers of CRC including aberrant crypt foci (ACF), bacterial enzymes and short chain fatty acids (SCFA) in a rodent model induced with 1,2-dimethylhydrazine dihydrochloride (DMH). Inulin group was taken as positive control in present study to compare novel GalOS protective effects. GalOS doses of 76–151 mg and inulin doses of 114 mg were given to different groups treated with DMH. Results showed that ACF formation was significantly (p ≤ 0.05) less in high dose GalOS group (27.3%). GalOS also had protective effects against DMH-induced body weight loss and showed higher level of cecal and fecal SCFA (acetate, propionate and butyrate). High doses of GalOS also resulted in significant (p ≤ 0.05) reduction of bacterial enzymatic activities. Increased populations of beneficial bacteria (bifidobacteria and lactobacilli) and decreased concentrations of harmful bacteria were observed in all prebiotics treatment groups. It can be concluded that novel GalOS exhibit robust protective activity against ACF formation in vivo.

Prebiotic galacto-oligosaccharides mitigate the adverse effects of iron fortification on the gut microbiome: a randomised controlled study in Kenyan infants

ObjectiveIron-containing micronutrient powders (MNPs) reduce anaemia in African infants, but the current high iron dose (12.5 mg/day) may decrease gut Bifidobacteriaceae and Lactobacillaceae, and increase enteropathogens, diarrhoea and respiratory tract...

Biochemical Characterization of the Functional Roles of Residues in the Active Site of the β-Galactosidase from Bacillus circulans ATCC 31382.

The β-galactosidase enzyme from Bacillus circulans ATCC 31382 BgaD is widely used in the food industry to produce prebiotic galactooligosaccharides (GOS). Recently, the crystal structure of a C-terminally truncated version of the enzyme (BgaD-D) has been elucidated. The roles of active site amino acid residues in β-galactosidase enzyme reaction and product specificity have remained unknown. On the basis of a structural alignment of the β-galactosidase enzymes BgaD-D from B. circulans and BgaA from Streptococcus pneumoniae, and the complex of BgaA with LacNAc, we identified eight active site amino acid residues (Arg185, Asp481, Lys487, Tyr511, Trp570, Trp593, Glu601, and Phe616) in BgaD-D. This study reports an investigation of the functional roles of these residues, using site-directed mutagenesis, and a detailed biochemical characterization and product profile analysis of the mutants obtained. The data show that these residues are involved in binding and positioning of the substrate and thus determine the BgaD-D activity and product linkage specificity. This study provides detailed insights into the structure–function relationships of the B. circulans BgaD-D enzyme, especially regarding GOS product linkage specificity, allowing the rational mutation of β-galactosidase enzymes to produce specific mixtures of GOS structures.