Detection of typical indigenous gut bacteria related to kanpyo Lagenaria siceraria var. hispida powder in murine caecum and human faecal cultures.

Kanpyo (KP) is an edible dried product produced by peeling the fruit of the gourd Lagenaria siceraria var. hispida; it is used in the traditional Japanese cuisine. The health functionality of KP due to its rich dietary fibre is expected to include a possible combined effect of KP-responsive indigenous gut bacteria (KP-RIB). However, its effect on the gut microbiota is unclear. To determine the effects of the KP on the gut microbiota and their host, Institute of Cancer Research mice were fed a high-sucrose diet containing no fibre (NF) or 5% (w/w) KP for 14 days, and their caecal microbiota was analysed by 16S rRNA (V4) amplicon sequencing. Higher faecal frequency and weight and lower spleen weight and spleen tumour necrosis factor-α levels were observed in KP-fed mice than in NF-fed mice (p < 0.05). KP increased and decreased the abundance of short-chain fatty acid producer Lachnospiraceae and obesity-inflammation related Allobaculum species, respectively. In the case of human faecal cultures, stool samples from five healthy volunteers were inoculated and incubated at 37 °C for 24 h anaerobically; 3.2% (w/v) KP suppressed putrefactive compounds (indole, phenol, and ammonia). KP increased butyrate-producer Faecalibacterium, acetate/lactate-producer Bifidobacterium, and Lachnospira. Furthermore, KP cultures showed high antioxidant and RAW264.7 macrophage cell activation capacities. These results suggest that KP-RIB and KP intake may synergistically affect host health. However, further studies are required to clarify the synergistic effects of KP and KP-RIB.

Effects of Sichuan pepper (huajiao) powder on disease activity and caecal microbiota of dextran sodium sulphate-induced inflammatory bowel disease mouse model.

BACKGROUND: Sichuan pepper [Zanthoxylum bungeanum; huajiao (HJ)] is a widely used spice in China and has better antioxidative, anti-glycation, and bile acid-lowering properties than cumin and coriander seeds. HJ affects inflammation-related cytokines and caecal microbiota in mice fed a low-fibre and high-sucrose diet. METHODS AND RESULTS: To determine the ameliorative effect of HJ on inflammatory bowel disease, C57BL/6 mice were divided into three groups and fed distilled water (control) or 3% (w/v) dextran sodium sulphate (DSS) in drinking water with normal chow containing 0% or 5% (w/w) HJ powder for seven days. After 6 days of feeding, diarrhoea, decreased body weight, and blood in faeces were observed in the DSS group. DSS treatment increased the spleen weight and damaged the colon tissue. These inflammatory indices were inhibited by HJ treatment. Amplicon sequencing of the 16S rDNA (V4) gene of the caecal content revealed a decrease in the alpha diversity (Simpson index D) in the DSS treatment group compared to the control group. The abundance of caecal Desulfovibrio, an inflammation-related genus, was higher and the caecal Lachnospiraceae and Bacteroides levels were lower in the DSS-treated mice than those in the control mice. However, HJ suppressed the DSS-induced changes in the caecal microbiota. CONCLUSION: HJ intake contributes to the reduction in inflammation and maintenance of the gut microbiota. However, the strong antioxidant properties of phenolic compounds and fermentability of water-soluble dietary fibres in HJ and their relationship with other functional properties warrant further investigation.

The effect of Sichuan pepper on gut microbiota in mice fed a high-sucrose and low-dietary fibre diet.

Sichuan pepper (Zanthoxylum bungeanum, HJ), a spice widely used in China, has antioxidative, anti-inflammatory, antibacterial, and anti-obesity properties. In this study, to confirm the value of HJ as a functional food, the in vitro antioxidant and bile acid-lowering capacities, as well as the effects on caecal microbiota, were compared with those of cumin (Cuminum cyminum, CM) and coriander (Coriandrum sativum, CR) seeds in Institute of Cancer Research (ICR) mice fed a high-sucrose and low-dietary fibre diet. The total phenolic content, superoxide anion radical-scavenging capacity, and Fe-reducing power of the HJ aqueous solution were higher than those of CM and CR (p < 0.05). The bile acid (taurocholic, glycocholic, and deoxycholic acids)-lowering capacity of the HJ suspension was also higher than those of CM and CR. Compared with mice fed a control diet (no fibre, NF), caecal Lactobacillus gasseri- and Muribaculum intestinale-like bacteria were higher in mice fed a diet containing 5% (w/w) of CM, CR, or HJ for 14 days. Bifidobacterium pseudolongum-, Lactobacillus murinus/animalis-, and Faecalibaculum rodentium-like bacteria were significantly increased, while Desulfovibrio-like bacteria were significantly decreased in the HJ group. In addition, CM and HJ may benefit specific metabolic functions of gut microbiota, such as starch, sucrose, and tyrosine metabolism. The tumour necrosis factor (TNF-α) concentration in the spleen tissue of ICR mice was decreased by the intake of spices. However, there were no changes in interleukin-2 (IL-2) and IL-10 levels in HJ fed mice. These results suggested that HJ has potential as a functional food related to gut microbiota. KEY POINTS: • Bididobacterium and Faecalibaculum in mice gut microbiota are increased by Sichuan pepper (HJ). • Desulfovibrionaceae, an inflammatory LPS producer, in mice gut microbiota is decreased by HJ. • HJ decreases pro-inflammatory TNF both in murine spleen tissue and in vitro macrophages.

Transition of microbial contamination on the surface of carcass during the cattle slaughter process.

In this study, we aimed to investigate how microbial contamination progresses on the carcass surface during the slaughter process. Cattle carcasses were tracked during a series of slaughter processes (five steps), and carcass surfaces (four parts) and equipment (nine types) were swabbed to investigate the bacterial contamination. Results showed that the outer surface (near the rear region of the flank [Top round] and [Top sirloin butt]) had significantly higher total viable counts (TVCs) than inner surface (p < 0.01) and that TVCs gradually decreased along the process. Enterobacteriaceae (EB) counts were high on the splitting saw and in top round region, and EB was detected on the inner surface of the carcasses. Furthermore, in some carcasses, Yersinia spp., Serratia spp., and Clostridium spp. present on top round and top sirloin butt immediately after skinning and remained on the carcass surface after the final process. These bacterial groups are detrimental to beef quality as they can grow in the package during cold distribution. Our results show that the skinning process is the most prone to microbial contamination, including psychrotolerant microorganisms. Moreover, this study provides information for understanding the dynamics of microbial contamination in the cattle slaughter process.

Detection of typical indigenous gut bacteria related to turmeric (Curcuma longa) powder in mouse caecum and human faecal cultures.

BACKGROUND: Turmeric (Curcuma longa; TM) is widely used as a spice and possesses anti-inflammatory, antioxidant, and antibacterial properties. The relationship between TM functions and gut microbiota is still unclear. METHODS AND RESULTS: To investigate the effect of TM on gut microbiota and to identify indigenous gut bacteria that are responsive to TM, we fed Institute of Cancer Research mice a diet containing either no fibre (NF, n = 6) or 5% (w/w) TM (n = 6) for 14 days. Moreover, we obtained human stool samples from four healthy volunteers and incubated the samples without (control) or with 2% (w/v) TM at 37 °C for 24 h. Subsequently, microbiota analysis in murine caecal samples and human faecal cultures was performed using 16S rRNA (V4) amplicon sequencing. Higher faecal weights (p < 0.01) and lower plasma triacylglycerol levels (p < 0.05) were measured in the TM-fed mice than in the NF-fed mice. Furthermore, TM feeding increased the abundance of butyrate-producing and other short-chain fatty acid (SCFA)-producing bacteria in mice as well as in human faecal cultures, and Roseburia bacteria were detected as TM-responsive indigenous gut bacteria (TM-RIB) both in mice and in human faecal cultures. Lastly, in the case of human faecal cultures, SCFA contents and antioxidant properties were higher in TM cultures than in control cultures (p < 0.05). CONCLUSION: TM appears to hold the potential to positively affect the host by altering the gut microbiota. Further studies are required to clarify the synergistic effects of TM and TM-RIB.

Detection of indigenous gut bacteria related to red chilli pepper (Capsicum annuum) in murine caecum and human faecal cultures.

BACKGROUND: Red chilli pepper (Capsicum annuum; RP) is a popular spice containing the active compound capsaicin. Indigenous gut bacteria and metabolism can affect host health. The functions of capsaicin, including the regulation of metabolic health and anti-oxidant properties, may be correlated with the gut microbiota. METHODS: To identify indigenous gut bacteria that are responsive to RP, Institute of Cancer Research mice fed a diet with no fibre or with 5% (w/w) RP for 14 days. Additionally, human stool samples collected from four healthy volunteers were incubated without (control) or with 2% (w/v) RP at 37 °C for 24 h. Microbiota in murine caecal samples and human faecal cultures were analysed using 16S rRNA (V4) amplicon sequencing. RESULTS: Compared with the microbiota in mice fed no-fibre diets, Lachnospiraceae spp.-, Muribaculaceae spp.-, and Phacaeicola vulgatus-like bacteria were defined as murine RP-responsive indigenous gut bacteria (RP-RIB). In the human faecal cultures, acetate and propionate levels were higher in RP cultures than in the control cultures. Subdoligranulum spp.-, Blautia spp.-, Faecalibacterium prausnitzii-, P. vulgatus-, and Prevotella copri-like bacteria were defined as human RP-RIB. Compared with control culture Fe-reducing power was increased in the culture with RP. CONCLUSION: RP increases the amount of short-chain fatty acid-producing bacteria and beneficial gut bacteria in mouse and human faecal cultures. Overall, RP could have a positive effect on the host by altering the gut microbiota.

Distribution of psychrophilic microorganisms in a beef slaughterhouse in Japan after cleaning.

The purpose of this study was to investigate the abundance and distribution of psychrophilic microorganisms associated with spoilage in beef slaughterhouse environments after cleaning. The processing lines and equipment used in slaughtering and boning were swabbed, and the microbial count was determined using a TSA and MRS medium and Chromocult® Coliform agar incubated at 15ºC and 37ºC, respectively. As a result, the brisket saw (handle side) and trolley hook were the most heavily contaminated with microorganisms, with each having a microbial adhesion rate of 66.7%. The microbial adhesion rates of the apron and milling cutter (edge side) were 50%, respectively, and those of the foot cutter (edge and handle side), splitting saw (edge side), and knife (handle side) were 33.3%, respectively. Next, four colonies were randomly isolated from the petri dish used for the bacterial count measurement to identify the predominant microbial species of the microorganisms attached to each equipment. As a result of Sanger sequencing analysis, yeasts such as Candida zeylanoides and Rhodotorula sp. and bacteria including Pseudomonas sp. and Rhodococcus sp. were identified from the equipment used in the slaughtering line, and it was assumed that these microorganisms were of environmental origin. In contrast, only Pseudomonas sp. and Candida zeylanoides were isolated from the boning line. Despite the use of cleaning operations, this study identified some equipment was contaminated with microorganisms. Since this equipment frequently comes into direct contact with the carcass, it is critical to thoroughly remove the microorganisms through accurate cleaning to prevent the spread of microbial contamination on the carcasses.

Dynamics of microbiota in the imported beef primal cuts during storage at different chilled temperatures.

Primal cuts of Australian beef transported by sea were stored under different chilled temperatures (0, 2, and 4 °C) for 6 weeks in different packaging conditions (aerobic or anaerobic packaging). The number of microorganisms and the transition of the microbiota were investigated using culture methods and amplicon sequencing. After 6 weeks of storage, the beef tended to show a high total viable count under aerobic packaging conditions and a high lactic acid bacteria count under anaerobic packaging conditions. The result of amplicon sequencing analysis showed that different beef samples had different predominant bacterial groups. Moreover, at high storage temperatures, Serratia sp. having high putrefactive activity showed increased abundance, while at low storage temperatures, Lactobacillus sp. showed increased abundance. Thus, differences in the packaging conditions and distribution temperatures after import affect the number of bacteria and the type of microorganisms in the Australian beef primal cuts, which may affect their quality.

In vitro antioxidant, anti-glycation, and bile acid-lowering capacity of peanut milk fermented with Lactiplantibacillus plantarum Kinko-SU4.

Plant-based milk-like products from soybeans and other legumes and nuts have been explored worldwide, owing to their nutritional and functional characteristics. This study was conducted to develop new functional food materials from peanut (Arachis hypogaea) milk (PM) with desirable health functions to mitigate lifestyle and age-related diseases. The antioxidant, anti-glycation and bile acid-lowering properties of PM fermented with lactic acid bacteria Lactiplantibacillus plantarum Kinko-SU4 (FPM) were determined in vitro. L. plantarum Kinko-SU4 lowered the pH level from 6.4 to 4.3, 3.9, and 3.7 at 10, 24, and 48 h, respectively. The lactic acid concentration was 4.4 mg/mL after 48 h of incubation. The starter degraded the dissolved proteins in PM, including Ara h 1, one of the peanut allergens. Although the total phenolic content was 36% lower in FPM than in unfermented PM, O2 - radical-scavenging capacity was high in FPM. Anti-glycation in a bovine serum albumin-fructose model and the bile acid-lowering capacities of PM were distinctly increased following fermentation. The result of this study infers that PM fermented with L. plantarum Kinko-SU4 can be considered a desirable food material to prevent and ameliorate chronic lifestyle diseases, particularly in the elderly.

Growth Inhibition of Listeria monocytogenes in Fresh White Cheese by Mustard Oil Microemulsion.

ABSTRACT: Although essential oils exhibit antimicrobial properties, their application is limited, owing to their strong volatility and poor water solubility. Emulsification is a valid strategy for improving chemical stability. In this study, we prepared a mustard oil (MO) emulsion with egg yolk lecithin and evaluated its antimicrobial activity against Listeria monocytogenes in vitro and in cheese curd. The particle size of the MO emulsion was approximately 0.19 µm and remained stable for 30 days of storage. The MO emulsion showed strong antimicrobial activity against L. monocytogenes in vitro. Moreover, 40 ppm of MO was sufficient to inhibit the growth of L. monocytogenes in culture, and the addition of 160 ppm of MO decreased the population of L. monocytogenes. When 50 ppm of emulsified MO was added to milk during cheese curd production and it was stored at 10°C for 10 days, the growth of L. monocytogenes was suppressed. When the cheese curd with MO emulsion was stored at 4°C, the bacterial count was significantly decreased (P < 0.05), and no bacterial growth was observed after 14 days of storage. Furthermore, the sensory characteristics of cheese curd with the MO emulsion were acceptable. These results indicate MO emulsions may be useful in controlling the growth of L. monocytogenes in fresh cheese.

Detection and isolation of typical gut indigenous bacteria in ICR mice fed wheat bran and wheat straw fibre.

Wheat bran (WB) and wheat straw fibre (WSF) are by-products of the wheat flour industry. To prove the existence of indigenous gut bacteria responsible for WB and WSF, the Institute of Cancer Research (ICR) mice were fed a diet containing no fibre (CS), 10% WB, or 5% WSF for 14 d. The caecal microbiome was analysed by 16S rDNA (V4 region) amplicon sequencing. Typical colonies were isolated and estimated by 16S rRNA gene BLASTn analysis. The predominant amplicon sequence variants in all diet groups belonged to Bifidobacterium pseudolongum- and Faecalibaculum rodentium-like bacteria. Lactobacillus johnsonii- and Limosilactobacillus reuteri-like bacteria were high in the WB group compared with those in the CS group. Lactobacillus johnsonii Wheat-1 and L. reuteri Wheat-12 strains could be isolated. Lactobacillus johnsonii Wheat-1 exhibited good fermentation activity in 10% (w/v) WB suspension. Superoxide anion radical scavenging capacity of the WB suspension was significantly increased by the fermentation.

Comparison between the Antimicrobial Activity of Essential Oils and Their Components in the Vapor Phase against Food-related Bacteria.

In this study, the antibacterial properties of the volatile components of four essential oils (cinnamon, clove, origanum, and peppermint oil) and five of their components (allyl isothiocyanate (AITC), carvacrol, citral, eugenol, and (+)-limonene) against five food-related bacteria (Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium, Pseudomonas fluorescens, and Enterococcus faecalis) were evaluated. The results of disc volatilization method revealed that AITC exhibited antibacterial activity against the five tested strains at the lowest concentration, as did cinnamon oil and carvacrol. Moreover, the total aerobic bacterial count in coleslaw salad was suppressed in all test groups treated with AITC compared to that in control.

Detection of low-mineral- and high-salt responsible caecal indigenous bacteria in ICR mice.

Both deficiency and overdose of minerals and salts negatively affect health. Changes in the dietary composition have immediate effects on the gut microbiota. This study was performed to clarify the presence of indigenous gut bacteria responsible for minerals and/or salts (MS-RIB). ICR mice were fed a diet containing 3.5% (w/w) mineral mix (control), 1% mineral mix (LM), or 3.5% mineral mix and 4% NaCl (HS) for 14 days. The caecal microbiota was examined using 16S rRNA gene (V4) amplicon sequencing. Consumption of drinking water was 2.5-fold higher in the HS group than in the other groups. Body weight gain was 55% lower in the HS group than in the other groups. At the family level, the relative abundance of Eryspelotrichaceae and Clostridiaceae was lower in the HS group than in the other groups. In contrast, the abundance of Bacteroidaceae was higher in the HS group. At the operational taxonomic unit level, Desulfovibrionaceaer-, Turicibacter sanguinis-, belonging to Eryspelotrichaceae, and Clostridium disporicum-like bacteria were dominant in the control group. Among these bacteria, T. sanguinis- and C. disporicum-like bacteria were markedly suppressed by HS. In the LM group, Bacteroides acidifaciens-like bacteria were suppressed. Suppression of C. disporicum and Turicibacter following consumption of the HS diet was the most notable effect, contrasting the results of previous studies.

Effects of tyndallization temperature on the sterility and quality of kamaboko.

In this study, kamaboko gels were tyndallized at various temperatures and sterilization efficiency and impact on quality parameters were assessed. The microbiological, physical, and chemical properties of kamaboko gels were determined throughout the tyndallization process. Superior sterilization efficiency was achieved by tyndallization at a higher temperature; and the combination of heat-induced germination and thermal inactivation of spores was proposed as the main reason. The process had minimal effect on the color of gels. While tyndallized gels heated at 80 °C possessed superior physical properties, all gels showed impaired quality with the progress of heating cycles. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the cause of alterations in quality differed depending on the processing temperature. This study suggests that the sterility of products could be improved by increasing the processing temperature, time or number of heating cycle.

Molecular subtyping for source tracking of Escherichia coli using core genome multilocus sequence typing at a food manufacturing plant.

When harmful bacteria are detected in the final product at a food manufacturing plant, it is necessary to identify and eliminate the source of contamination so that it does not occur again. In the current study, the source of contamination was tracked using core genome multilocus sequence typing (cgMLST) analysis in cases where Escherichia coli was detected in the final product at a food manufacturing plant. cgMLST analysis was performed on 40 strains of E. coli collected from the environment [floor (26 strains), drainage ditch (5 strains), container (4 strains), post-heating production line (1 strain)] and products [final product (3 strains) and intermediate product (1 strain)]. In total, 40 E. coli isolates were classified into 17 genogroups by cgMLST analysis. The 4 E. coli strains isolated from the intermediate and final products were classified into two genogroups (I and II). Certain isolates collected from the environment also belonged to those genogroups, it was possible to estimate the transmission of E. coli in the manufacturing plant. Thus, the dynamics of E. coli in the food manufacturing location were clarified by using cgMLST analysis. In conclusion, our results indicate that cgMLST analysis can be effectively used for hygiene management at food manufacturing locations.

Dynamics of microbiota in Japanese Black beef stored for a long time under chilled conditions.

In this study, changes in the microbiota of Japanese Black beef carcasses, which are expected to be transported for a long time in chilled temperatures, were investigated. Three Japanese Black beef samples (carcasses A, B, and C) immediately after slaughter were stored at 0 °C for 15 weeks under aerobic and vacuum conditions. The initial bacterial counts were 50 CFU/g for carcass A and less than the reliable quantitative detection limit for carcasses B and C. Under aerobic storage conditions, the bacterial count increased to 8.0 log CFU/g or higher, which is a measure of putrefaction, at 6-9 weeks. Under anaerobic storage conditions, the bacterial counts of carcasses A and C reached 3.5-6.5 log CFU/g, but carcass B showed no bacterial growth during the 15-week storage period. The predominant group was Pseudomonas spp. under aerobic conditions and Serratia spp. under anaerobic conditions. To the best of our knowledge, there is no previous study investigating the transition of microbiota when Japanese Black beef is stored at low temperatures for a long period of time, and the results of this study are considered very important findings for the expansion of international trade of Japanese Beef in the future.

Typical gut indigenous bacteria in ICR mice fed a soy protein-based normal or low-protein diet.

For patients with inflammatory bowel disease, cow's milk allergy, and lactose intolerance, soymilk is a potential alternative to cow's milk. In this study, we aimed to identify the effects of a soy protein-based low-protein diet on the body and organ weights and the gut microbiome of six-week-old mice fed a diet containing 20% (SP) or 5% (LP) soy protein for 14 days via 16S rRNA (V4) amplicon sequencing. Body weight gain (growth) and liver, spleen, and fat tissue weight were significantly suppressed by the LP diet. Operational taxonomic unit numbers and α-diversity were lower in the LP group than in the SP group. A principal coordinate analysis revealed differences in the gut microbiome compositions of SP and LP mice. The abundances of caecal Roseburia sp., Alistipes sp., and bacteria from the family Muribaculaceae were lower in the LP group than in the SP group. In contrast, the abundance of Desulfovibrionaceae, which is positively correlated with inflammation, was higher in the LP group than in the SP group. These results differed from the effects of a milk casein-based low-protein diet (reported previously). Based on these findings, we conclude that the undesirable effects of a low-protein diet and/or protein deficiency are related to changes in the gut microbiome composition and may differ depending on the kind of proteins used.

Impact of pH and protein hydrophobicity on norovirus inactivation by heat-denatured lysozyme.

Norovirus, the leading cause of non-bacterial food poisoning, is responsible for several outbreaks associated with bivalves and ready-to-eat food products worldwide. As norovirus is resistant to alcohol, which is commonly used in food manufacturing processes, sodium hypochlorite is used for its inactivation. However, sodium hypochlorite has two disadvantages: it cannot be added to foods, and its effect is significantly reduced in the presence of organic compounds. Thus, a novel disinfectant against norovirus is urgently required for food hygiene. Thermally denatured egg white lysozyme inactivates norovirus; however, the optimal inactivating conditions and the underlying mechanism are unclear. In the present study, the inactivating mechanism of heat-denatured lysozyme against norovirus was analyzed using murine norovirus strain 1 (MNV-1). We found that the inactivating effect was enhanced by adjusting the pH of the lysozyme solution before thermal denaturation to 6.5 or higher. The reaction of heat-denatured lysozyme and MNV-1 was irreversible, and norovirus was completely inactivated after exposure to heat-denatured lysozyme. Furthermore, it was found that lysozyme residues 5-39 contributed to the norovirus-inactivating effect. Notably, the hydrophobicity and positive charges in this region contributed to the norovirus-inactivating effect, as evidenced by the norovirus inactivation test using mutated residues 5-39. These findings are novel and highlight the possible application of heat-denatured lysozyme as a disinfectant against norovirus in a wide range of food processes.

Detection and isolation of the typical gut indigenous bacteria from ddY mice fed a casein-beef tallow-based or egg yolk-based diet.

The effects of whole egg on the cecal microbiome of ddY mice has been reported. To investigate the existence of susceptible indigenous bacteria (SIB) to egg yolks (EY), mice were fed a diet containing either 20% (w/w) milk casein and 17% beef tallow (CT) or 12% milk casein and 27% EY for 14 days, and then, the cecal microbiome was analyzed by 16S rRNA (V4) amplicon sequencing. To isolate the typical species in each diet group, culture-dependent viable bacterial counts were determined on Blood Liver (BL) and Gifu Anaerobic Medium (GAM) agar plates. The amplicon sequencing analysis revealed typical CT-SIB, such as Lachnospiraceae-like bacteria, and EY-SIB, such as Allobaculum-, Lactobacillus murinus-, and Bacteroides vulgatus-like bacteria. Two of the detected SIB species, L. murinus- and B. vulgatus-like bacteria, were successfully isolated from the BL and GAM agar plates and defined using a 16S rDNA BLAST search. PRACTICAL APPLICATIONS: The SIB defined in the CT and EY groups might have some effects on the nutritional and functional chemical compounds in the milk casein, beef tallow, and/or EY. Analysis of its functional properties of the isolates might develop the new and unique probiotic strains.

Detection and isolation of low molecular weight alginate- and laminaran-susceptible gut indigenous bacteria from ICR mice.

Alginate and laminaran are the main water-soluble polysaccharides in edible brown algae such as arame Eisenia bicyclis. To determine the alginate- and/or laminaran-susceptible indigenous bacteria (SIB) in the gut, the caecal microbiomes of ICR mice fed a diet containing 2% low molecular weight (LMW ≒50 kDa) alginate or laminaran were analysed by 16S rRNA gene (V4) amplicon sequencing. At the phylum level abundances, compared to those in mice fed a no-fibre diet, Firmicutes was lower and Bacteroidetes was higher in both LMW alginate- or laminaran-fed mouse groups. At the operational taxonomic unit level, Bacteroides acidifaciens- and Bacteroides intestinalis-like bacteria were considered alginate- and laminaran-SIB, respectively. B. acidifaciens PS-4 isolated from the ICR mice fermented LMW alginate and laminaran and mainly produced succinate. B. intestinalis ALB-11 also isolated from these mice fermented laminaran and mainly produced lactate. These SIB might exert interactive effects with edible brown algal consumption and affect host health.