Temporal changes in the fermentation characteristics, bacterial community structure and the functionality of the predicted metagenome of a batch fermenter medium containing the upper gastrointestinal enzyme resistant fraction of white sorghum (Sorghum bicolor L. Moench).

Sorghum is a potential prebiotic ascribed to the high native resistant starch (RS) content. Our previous studies on raw sorghum have revealed prominent amino acid fermentation despite the high RS content. Interestingly, autoclaved-freeze-dried sorghum fed rats exhibited beneficial microbial and biochemical profiles. Having a keen interest to reciprocally scrutinize the underlying mechanisms behind these contrasting outcomes, we used an in vitro porcine batch fermentation model. The fermentable substrates in raw and autoclaved-freeze-dried (three cycles) sorghum (AC) after in vitro gastrointestinal digestion fostered similar bacterial community structures, yet with significant differences in the characteristic amylolytic microbial taxa abundance and their temporal variation. Further, significant differences in the concentration of organic acids in raw and AC manifested the differences in the predicted abundance of the underlying pathways of carbohydrate and organic acid metabolism. Thus, this study highlights the propensity of the heat-moisture treatment of sorghum in modifying the fermentability of its RS.

Involvement of the vagus nerve and hepatic gene expression in serum adiponectin concentrations in mice

Several humoral factors, such as adiponectin and urate, have been suggested to affect metabolic syndromes. Previously, we reported a reduction in blood adiponectin concentrations after a high-fructose diet partially via the vagus nerve in rats. Although a lithogenic diet (LD), i.e., supplementation of a normal control diet (CT) with 0.6% cholesterol and 0.2% sodium cholate, reduced blood adiponectin concentrations, the involvement of the vagus nerve in this mechanism remains unclear. To estimate the involvement of the vagus nerve in the regulation of blood adiponectin concentrations using an LD, male imprinting control region mice that had been vagotomized (HVx) or only laparotomized (Sham) were administered a CT or an LD for 10 weeks. Serum adiponectin concentrations in the Sham-LD, HVx-CT, and HVx-LD groups were reduced by half compared with the Sham-CT group. The hepatic mRNA levels of fibroblast growth factor 21 (Fgf21), which reportedly stimulates adiponectin secretion from white adipose tissue, were lower in the LD groups compared with the CT groups. HepG2 hepatoma cells showed that various bile acids reduced the mRNA expression of FGF21. Moreover, the LD increased serum urate concentrations and reduced hepatic expressions of the acyl-CoA oxidase 1 (Acox1) mRNA and glucokinase, suggesting insufficient regeneration of ATP from AMP. In conclusion, serum adiponectin concentration may be regulated via the vagus nerve in normal mice, whereas a reduction of hepatic Fgf21 mRNA by bile acids may also lower serum adiponectin levels. Moreover, the LD may promote hepatic AMP accumulation and subsequently increase the serum urate concentration in mice. (AU)

Involvement of the vagus nerve and hepatic gene expression in serum adiponectin concentrations in mice

Several humoral factors, such as adiponectin and urate, have been suggested to affect metabolic syndromes. Previously, we reported a reduction in blood adiponectin concentrations after a high-fructose diet partially via the vagus nerve in rats. Although a lithogenic diet (LD), i.e., supplementation of a normal control diet (CT) with 0.6% cholesterol and 0.2% sodium cholate, reduced blood adiponectin concentrations, the involvement of the vagus nerve in this mechanism remains unclear. To estimate the involvement of the vagus nerve in the regulation of blood adiponectin concentrations using an LD, male imprinting control region mice that had been vagotomized (HVx) or only laparotomized (Sham) were administered a CT or an LD for 10 weeks. Serum adiponectin concentrations in the Sham-LD, HVx-CT, and HVx-LD groups were reduced by half compared with the Sham-CT group. The hepatic mRNA levels of fibroblast growth factor 21 (Fgf21), which reportedly stimulates adiponectin secretion from white adipose tissue, were lower in the LD groups compared with the CT groups. HepG2 hepatoma cells showed that various bile acids reduced the mRNA expression of FGF21. Moreover, the LD increased serum urate concentrations and reduced hepatic expressions of the acyl-CoA oxidase 1 (Acox1) mRNA and glucokinase, suggesting insufficient regeneration of ATP from AMP. In conclusion, serum adiponectin concentration may be regulated via the vagus nerve in normal mice, whereas a reduction of hepatic Fgf21 mRNA by bile acids may also lower serum adiponectin levels. Moreover, the LD may promote hepatic AMP accumulation and subsequently increase the serum urate concentration in mice. (AU)

Involvement of the vagus nerve and hepatic gene expression in serum adiponectin concentrations in mice.

Several humoral factors, such as adiponectin and urate, have been suggested to affect metabolic syndromes. Previously, we reported a reduction in blood adiponectin concentrations after a high-fructose diet partially via the vagus nerve in rats. Although a lithogenic diet (LD), i.e., supplementation of a normal control diet (CT) with 0.6% cholesterol and 0.2% sodium cholate, reduced blood adiponectin concentrations, the involvement of the vagus nerve in this mechanism remains unclear. To estimate the involvement of the vagus nerve in the regulation of blood adiponectin concentrations using an LD, male imprinting control region mice that had been vagotomized (HVx) or only laparotomized (Sham) were administered a CT or an LD for 10 weeks. Serum adiponectin concentrations in the Sham-LD, HVx-CT, and HVx-LD groups were reduced by half compared with the Sham-CT group. The hepatic mRNA levels of fibroblast growth factor 21 (Fgf21), which reportedly stimulates adiponectin secretion from white adipose tissue, were lower in the LD groups compared with the CT groups. HepG2 hepatoma cells showed that various bile acids reduced the mRNA expression of FGF21. Moreover, the LD increased serum urate concentrations and reduced hepatic expressions of the acyl-CoA oxidase 1 (Acox1) mRNA and glucokinase, suggesting insufficient regeneration of ATP from AMP. In conclusion, serum adiponectin concentration may be regulated via the vagus nerve in normal mice, whereas a reduction of hepatic Fgf21 mRNA by bile acids may also lower serum adiponectin levels. Moreover, the LD may promote hepatic AMP accumulation and subsequently increase the serum urate concentration in mice.

Gut microbiota-derived lipid metabolites facilitate regulatory T cell differentiation.

Commensal bacteria-derived metabolites are critical in regulating the host immune system. Although the impact of gut microbiota-derived hydrophilic metabolites, such as short-chain fatty acids, on immune cell functions and development has been well documented, the immunomodulatory effects of gut microbiota-derived lipids are still of interest. Here, we report that lipid extracts from the feces of specific-pathogen-free (SPF), but not germ-free (GF), mice showed regulatory T (Treg)-cell-inducing activity. We conducted RP-HPLC-based fractionation and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based lipidome profiling and identified two bioactive lipids, 9,10-dihydroxy-12Z-octadecenoic acid (9,10-DiHOME) and all-trans retinoic acid (atRA), with Treg-inducing activity in vitro. The luminal abundance of 9,10-DiHOME in the large intestine was significantly decreased by dextran sulfate sodium (DSS)-induced colitis, indicating that 9,10-DiHOME may be a potential biomarker of colitis. These observations implied that commensal bacteria-derived lipophilic metabolites might contribute to Treg development in the large intestine.

Beneficial health effects of polyphenols metabolized by fermentation.

High daily intake of polyphenol-rich meal in some countries could be regarded as a healthy meal. However, the knowledge about the bioavailability and functionality of the exiting amounts of polyphenol into the large intestine needs to be elucidated, particularly the beneficial health effects and its fermentation characteristics during fermentation. Thus, this review focuses on the influence of polyphenols metabolized by fermentation and elucidates their health attributes. Besides, it also summarized the potential benefits of polyphenols and discussed the need for further research to fully understand the health attributes of polyphenols.

In vitro colonic fermentation characteristics of barley-koji differ from those of barley.

Barley-koji is prepared by inoculating barley, a beneficial prebiotic source, with the fungi Aspergillus luchuensis mut. kawachii. In this study, the prebiotic effects of barley-koji on human colonic microbiota were evaluated in vitro compared with barley, using pig feces. The enzyme-resistant fraction of the following sample groups each was added to respective fermenters: cellulose, barley (Commander and ß104), and barley-koji (Commander-koji and ß104-koji). Short-chain fatty acid and ammonia-nitrogen production increased and decreased, respectively, in barley-koji and barley groups. Furthermore, the propionate concentration increased in the barley group, showing a positive correlation with the abundance of the genus Dialister. In the barley-koji group, however, acetate and n-butyrate concentrations increased during the early stages of incubation, and the relative abundance of the genus Megasphaera was higher than those of the other genera. Therefore, this study demonstrated that barley-koji might possess beneficial physiological properties for colonic fermentation, which differ from those of barley.

Skate-skin mucin, rich in sulfated sugars and threonine, promotes proliferation of Akkermansia muciniphila in feeding tests in rats and in vitro fermentation using human feces.

Dietary factors, affect Akkermansia muciniphila (AM) abundance in the colon, have attracted attention, driven by the inverse correlation between AM abundance and metabolic disorders. We prepared skate-skin mucin (SM), porcine stomach mucin (PM), and rat gastrointestinal mucin (RM). SM contained more sulfated sugars and threonine than PM or RM. Rats were fed a control diet or diets including SM, PM, or RM (15 g/kg), or SM (12 g/kg) from 5 different threonine contents for 14 d. Cecal total bacteria and AM were less and more numerous, respectively, in SM-fed rats than the others, but SM did not affect microbial species richness. Low-threonine SM did not induce AM proliferation. The in vitro fermentation with human feces showed that the rate of AM increase was greater with SM than PM. Collectively, heavy SM sulfation facilitates a priority supply of SM-derived amino sugars and threonine that promotes AM proliferation in rats and human feces.

Dietary Ethanolamine Plasmalogen Alleviates DSS-Induced Colitis by Enhancing Colon Mucosa Integrity, Antioxidative Stress, and Anti-inflammatory Responses via Increased Ethanolamine Plasmalogen Molecular Species: Protective Role of Vinyl Ether Linkages.

Dietary ethanolamine plasmalogen (PlsEtn) has been reported to have several health benefits; however, its functional role during colon pathophysiology remains elusive. The present study investigated the anticolitis effect of dietary ethanolamine glycerophospholipids (EtnGpls) with high PlsEtn from ascidian muscle (86.2 mol %) and low PlsEtn from porcine liver (7.7 mol %) in dextran sulfate sodium (DSS)-induced colitis in mice. Dietary EtnGpls lowered myeloperoxidase activity, thiobarbituric acid-reactive substances, proinflammatory cytokines and proapoptosis-related protein levels in colon mucosa after 16 days of DSS treatment, with ascidian muscle (0.1% EtnGpl in diet) showing higher suppression than porcine liver (0.1% EtnGpl in diet). Moreover, dietary EtnGpls suppressed DSS symptoms after 38 days of DSS treatment as evidenced by increased body weight, colon length, and ameliorated colon mucosa integrity. Additionally, dietary EtnGpls elevated short-chain fatty acid production in DSS-treated mice. Altogether, these results indicate the potential of utilizing diets with abundant PlsEtn for the prevention of colon inflammation-related disorders.

Combined effects of BARLEYmax and cocoa polyphenols on colonic microbiota and bacterial metabolites in vitro.

BARLEYmax, a barley variety, and cocoa polyphenols (CPPs) have been reported to affect bacterial metabolites in the colon. This study aimed to evaluate the combined effects of BARLEYmax and CPPs supplementation on fecal microbiota in vitro using pig feces for 48 h. The relative abundances of the family Clostridiaceae and the genus Clostridium and ammonia-nitrogen production were decreased by both BARLEYmax and CPP supplementation, and there was a positive correlation between their abundances and the ammonia-nitrogen concentration. Although acetate and n-butyrate production was decreased by CPP supplementation, their concentrations were maintained at a higher level in the BARLEYmax + CPP group than in the cellulose (control) and cellulose + CPP groups. Therefore, this study demonstrated that a combination of BARLEYmax and CPPs may be beneficial in maintaining higher short-chain fatty acid production and the elimination of potentially harmful factors. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00959-z.

Deciphering the colonic fermentation characteristics of agavin and digestion-resistant maltodextrin in a simulated batch fermentation system.

Gut microbial fermentation of soluble dietary fibers promotes general and substrate-specific health benefits. In this study, the fermentation characteristics of two soluble branched-dietary fibers, namely, agavin (a type of agave fructans) and digestion-resistant maltodextrin (RD) were investigated against cellulose, using a simulated colonic fermenter apparatus employing a mixed culture of swine fecal bacteria. After 48 h of complete fermentation period, the microbial composition was different among all groups, where Bifidobacterium spp. and Lactobacillus spp. dominated the agavin treatment, while the members of the families Lachnospiraceae and Prevotellaceae dominated the RD treatment. Agavin treatment exhibited a clearly segregated two-phased prolonged fermentation trend compared to RD treatment as manifested by the fermentation rates. Further, the highest short-chain fatty acids production even at the end of the fermentation cycle, acidic pH, and the negligible concentration of ammonia accumulation demonstrated favorable fermentation attributes of agavin compared to RD. Therefore, agavin might be an effective and desirable substrate for the colonic microbiota than RD with reference to the expressed microbial taxa and fermentation attributes. This study revealed a notable significance of the structural differences of fermentable fibers on the subsequent fermentation characteristics.

Bile acids induced hepatic lipid accumulation in mice by inhibiting mRNA expression of patatin-like phospholipase domain containing 3 and microsomal triglyceride transfer protein.

Preliminary studies have shown that a lithogenic diet (LG), which contains cholesterol and cholic acid, induces gallstones and hepatic lipid accumulation (HLA), and reduction of blood triglyceride in mice. We hypothesized that an LG induces HLA by diminishing hepatic triglyceride excretion; however, there is no clear understanding of the mechanism of LG-induced HLA. This study aimed to investigate transcript expression related to the synthesis, expenditure, and efflux of hepatic triglyceride, in mice fed an LG for 4 weeks. Results showed lower plasma concentrations of triglyceride in the LG group than in the control group, but no symptoms of hepatic injury were observed. Hepatic mRNA expressions of patatin-like phospholipase domain containing 3 (Pnpla3), microsomal triglyceride transfer protein (Mttp), and acyl-CoA oxidase 1 (Acox1) were also reduced in the LG group. Deoxycholic acid and lithocholic acid promoted intracellular lipid accumulation, reduced triglyceride concentration in media, and suppressed expression of PNPLA3 and MTTP in HepG2 human hepatoma cells. These findings suggest that deoxycholic acid and lithocholic acid promote HLA by inhibiting the expression of PNPLA3, ACOX1, and MTTP that are involved in lipid metabolism.

Dry-aged beef manufactured in Japan: Microbiota identification and their effects on product characteristics.

We aimed to determine the mold, yeast, and bacterial distributions in dry-aged beef (DAB) manufactured in Hokkaido, Japan, and to study their effects on meat quality compared to wet-aged beef (WAB). Two rump blocks from Holstein steer were dry- and wet-aged for 35 days at 2.9 °C and 90% RH. The psychrophilic molds Mucor flavus and Helicostylum pulchrum and other fungi (Penicillium sp. and Debaryomyces sp.) appeared on the crust of DAB, while lactic acid bacteria and coliforms were suppressed in the inner part of the meat. The composition of C16:0, C18:0, and C18:1 fatty acids did not differ between DAB and WAB, while more C17:0 fatty acids were detected in DAB. Dry aging suppressed acids and increased the production of various aroma compounds with mushroom-like, nutty, and other pleasant flavors. The meat quality and free amino acid (FAA) contents of DAB and WAB did not differ significantly. In this study, we identified major molds on DAB, which might contribute to an increase in aroma. Keywords: dry-aged beef; Mucor flavus; Helicostylum pulchrum; psychrophilic mold; meat quality; volatile aroma compounds.

Effect of polyphenols isolated from purple sweet potato (Ipomoea batatas cv. Ayamurasaki) on the microbiota and the biomarker of colonic fermentation in rats fed with cellulose or inulin.

A polyphenol-rich diet has been associated with various health benefits. This study assessed the effects of polyphenol/anthocyanin isolated from a purple sweet potato (Ipomoea batatas cv. Ayamurasaki) on colonic fermentation in cellulose- or inulin-fed rats. Male Fischer-344 rats were assigned to one of these experimental diets: 5% cellulose (CEL), 5% CEL + 1% purple sweet potato polyphenol extract (CELP), 5% inulin (INU), and 5% INU + 1% purple sweet potato polyphenol extract (INUP) in each diet. The purple sweet potato polyphenol extract (PSPP) increased the relative abundance of Dorea and reduced the relative abundances of Oscillospira and Bacteroides in cellulose- or inulin-fed rats, respectively. Besides, PSPP reduced the caecal iso-butyrate and pH in the cellulose-fed rats. Further, PSPP triggered an increase in the caecal mucin level when combined with cellulose and increased the caecal IgA level while reducing the indole production in both the cellulose- or inulin-fed rats. Finally, PSPP may have different effects on the intestinal fermentation properties depending on the fermentability of dietary fiber associated with it. Therefore, this study demonstrated that dietary inclusion of polyphenol/anthocyanin from purple sweet potato might confer positive health attributes to the host gut.

Frozen Autoclaved Sorghum Enhanced Colonic Fermentation and Lower Visceral Fat Accumulation in Rats.

As raw sorghum is not able to influence considerable colonic fermentation despite its higher resistant starch (RS) content, our study aimed to investigate the effects of frozen autoclaved sorghum on colonic fermentation. Fischer 344 rats were fed frozen cooked refined (S-Rf) and whole (S-Wh) sorghum diets and were compared against α-corn starch (CON) and high amylose starch (HAS) fed rats for zoometric parameters, cecal biochemical and microbiological parameters. Sorghum fed rats exhibited significantly lower feed intake and visceral adipose tissue mass compared to CON. Bacterial alpha diversity was significantly higher in the sorghum fed rats compared to HAS and the two sorghum fed groups clustered together, separately from HAS and CON in the beta diversity plot. Serum non-High Density Lipoprotein cholesterol and total cholesterol in S-Rf group were significantly lower compared to CON, while total fecal bile excretion was also significantly higher in the two sorghum fed groups. Lower visceral adiposity was correlated with lower feed intake, RS content ingested and cecal short chain fatty acid (SCFA) contents. Thus, higher RS inflow to the colon via frozen autoclaved sorghum might have influenced colonic fermentation of RS and the resultant SCFA might have influenced lower adiposity as manifested by the lower body weight gain.

In vitro fermentation potential of the residue of Korean red ginseng root in a mixed culture of swine faecal bacteria.

Agricultural by-products such as the ginseng residue contain dietary fibre. This study was aimed at investigating the intestinal fermentation potential of the residue of Korean red ginseng root using an in vitro simulator of the colon using swine fecal bacteria. pH-Controlled glass fermentors were used to conduct a small scale in vitro batch fermentation under anaerobic conditions for 48 h. One of the following substrates was included in each fermentor: commercial cellulose (CEL), xylooligosaccharide (XOS), and crude ginseng-insoluble fibre (CGF). The pH was lower (p < 0.05) and the production of total short chain fatty acid was increased (p < 0.05) in the XOS and CGF groups compared with the CEL group after 6 h of incubation. The α-diversity analysis of the microbial community at 48 h showed that the number of bacterial species was (p < 0.05) reduced in the XOS and CGF groups compared with that in the CEL group. ß-Diversity of the microbial population at 48 h showed that all groups were clustered differently. The relative abundance of Bifidobacterium and Prevotella in the CGF group were significantly (p < 0.05) higher than those in the CEL and XOS groups. Ammonia nitrogen production in the XOS and CGF groups was (p < 0.05) lower after 6 h of incubation, and skatole production in the CGF group was (p < 0.05) lower at 48 h than that in the CEL group. These results suggested that the ginseng residue might be fermentable in the large intestine and thus would promote the maintenance of a healthy colonic environment in the host.

Dietary adzuki bean paste dose-dependently reduces visceral fat accumulation in rats fed a normal diet.

The aim of this study was to evaluate the dose-dependent effect of adzuki bean (Vigna angularis) paste (ABP) on visceral fat accumulation in rats. ABP is a rich source of indigestible carbohydrates (18.5%) with fiber and resistant starch (RS) contents of 14.5% and 4.0%, respectively. Animals were fed one of the following diets, control (CON), 30% ABP or 58.9% ABP for 28 days. The daily dietary energy intake was lowered (p < 0.05) and reduced visceral fat accumulation and lower serum lipid levels were observed in ABP fed groups. ABP consumption dose-dependently increased (p < 0.05) the daily fecal lipid and fecal acidic sterol excretions. On the other hand, cecal content and fecal moisture content in the 58.9% ABP group were greater (p < 0.05) than the CON group, while there was no significant difference between the two ABP fed groups. Both 30% and 58.9% ABP diets had significantly (p < 0.05) higher contents of cecal acetic, propionic and n-butyric acids, and lowered cecal pH, independently of the ABP dose. Microbial community data of rats fed ABP diets exhibited higher alpha-diversities than the rats fed CON diet, based on the Shannon Index and the number of observed species index, where the two ABP groups exhibited a similar alpha diversity. The weighted UniFrac-based principal coordinate analysis plot of cecal microbial community data showed that the ABP had a substantial effect on the cecal microbial composition. Furthermore, cecal bacterial 16S rRNA gene sequencing revealed that the ABP supplemented diets decreased the ratio of Firmicutes to Bacteroidetes. These findings suggested that the cecal fermentation of fiber and RS in ABP, might have decreased the energy intake, altered the gut microbiota composition, increased fecal lipid output, and thereby reduced fat accumulation in rats.

Effects of Sake lees (Sake-kasu) supplementation on the quality characteristics of fermented dry sausages.

Sake lees (Sake-kasu) are the sediments of Japanese sake brewing process from fermented rice with Aspergillus oryzae and yeasts. Sake lees contain various enzymes and metabolites derived from the Sake starter culture, and expected to add aroma, flavor and softness to sausages. We investigated the effects of Sake lees supplementation on fermented dry sausage characteristics over an aging period of 35 days. Sake lees supplementation significantly accelerated sarcoplasmic and myofibrillar protein decomposition and increased peptide and free amino acid content compared to untreated sausage meat. Sake lees significantly acidified the sausages, enhanced their sour taste, and influenced their acceptability. Sake lees supplementation also significantly improved the hardness of the final product and conferred a preferable flavor to it. These results suggest that the various enzymes and compounds in Sake lees improve the flavor and texture of fermented dry sausages.

Effects of Raw Potato Starch with High Resistant Starch Levels on Cecal Fermentation Properties in Rats.

The effects of potato starch, isolated from Snowden (SD) and Kitahime (KH) varieties, on cecal fermatation properties in rats were evaluated. In high-amylose cornstarch (HAS), SD and KH groups, cecal acetate and total short-chain fatty acid concentrations were increased and cecal pH was lowered compared to control (CON) group. Further, cecal immunoglobulin A levels were increased and cecal ammonia-nitrogen, p-cresol, skatole and indole concentrations were lowered in HAS, SD and KH groups compared to the CON group. Therefore, potato starch might possess beneficial intestinal fermentation properties.

In Vivo Colonic Fermentation of Sorghum (Sorghum bicolor L.): Important Correlations Observed among the Physiological Parameters of Cecum, Liver, Adipose Tissue and Fasting Serum Lipid Profile.

High amylose corn starch (HAS), whole grain sorghum (S-Wh), refined sorghum (S-Rf) and α-corn starch (CON) diets were fed to animals for 1 mo aiming to examine the physiological effects of resistant starch inclusion in the diet from grains. HAS exhibited significantly lower feed intake, final body weight, serum lipid profile with significantly higher cecal parameters and short chain fatty acid (SCFA) contents. S-Wh group exhibited significantly higher body weight, feed intake and serum lipid parameters compared to other 3 groups. Cecal fermentation was not seemed to be prominent in the CON, S-Wh and S-Rf groups with respect to lower cecal parameters and SCFA contents. The cecal microbial compositions in HAS, S-Wh and CON/S-Rf exhibited 3 distinct clusters suggesting a significant effect of the cecal microbial composition on cecal parameters, SCFA contents and physiological parameters.