High poly-γ-glutamic acid-containing natto improves lipid metabolism and alters intestinal microbiota in mice fed a high-fat diet.

Several beneficial effects of poly-γ-glutamic acid (γ-PGA) have been reported. To test whether natto, a fermented soy food rich in γ-PGA, can improve intestinal microbiota content and lipid metabolism in a high-fat diet, we compared the intestinal microbiota content, plasma, liver, and fecal contents, and changes in gene expression in the livers and large intestines of a group of mice fed a high-fat diet supplemented with cooked soybeans (SC group) and a group fed a high-fat diet supplemented with natto (NA group) for 42 days; high-fat diet-fed mice were used as a control (Con group). Hepatic lipid levels were significantly lower, the fecal bile acid and lipid levels were significantly greater, and the Bacteroidetes/Firmicutes ratio was significantly higher in the SC and NA groups as compared to Con group. Additionally, plasma glucose and triglyceride levels, the expression of liver fatty acid synthase, and the relative abundance of Lactobacillaceae was significantly higher in the NA group than in the Con group. Although both natto and cooked soybeans impacted the metabolic response to a high-fat diet, the addition of natto had a greater effect on glucose and lipid metabolism. γ-PGA may play an important role in natto functionality.

Effects of Bacillus subtilis Natto Strains on Antiviral Responses in Resiquimod-Stimulated Human M1-Phenotype Macrophages.

Bacillus subtilis natto is used in the production of natto, a traditional fermented soy food, and has beneficial immunomodulatory effects in humans. Single-stranded RNA (ssRNA) viruses, including influenza and coronavirus, often cause global pandemics. We proposed a human cell culture model mimicking ssRNA viral infection and investigated the ability of B. subtilis natto to induce antiviral effects in the model. The gene expressions were analyzed using quantitative real-time reverse transcription PCR. M1-phenotype macrophages derived from THP-1 cells strongly express the Toll-like receptor 8 (76.2-hold), CD80 (64.2-hold), and CCR7 (45.7-hold) mRNA compared to M0 macrophages. One µg/mL of resiquimod (RSQ)-stimulation induced the expression of IRF3 (1.9-hold), CXCL10 (14.5-hold), IFNß1 (3.5-hold), ISG20 (4.4-hold), and MxA (1.7-hold) mRNA in the M1-phenotype macrophages. Based on these results, the RSQ-stimulated M1-phenotype macrophages were used as a cell culture model mimicking ssRNA viral infection. Moreover, the B. subtilis natto XF36 strain induced the expression of genes associated with antiviral activities (IFNß1, IFNλ1, ISG20, and RNase L) and anti-inflammatory activities (IL-10) in the cell culture model. Thus, it is suggested that the XF36 suppresses viral infections and excessive inflammation by inducing the expression of genes involved in antiviral and anti-inflammatory activities.

Effects of a high-γ-polyglutamic acid-containing natto diet on liver lipids and cecal microbiota of adult female mice.

Natto is a traditional Japanese fermented soy product high in γ-polyglutamic acid (γ-PGA), whose beneficial effects have been reported. We prepared high-γ-PGA natto and compared the dietary influence on liver lipids and cecal microbiota in mice fed a diet containing it or a standard diet. The mice were served a 30% high-γ-PGA natto diet (PGA group) or standard diet (Con group) for 28 days. Liver lipids, fecal lipids, and fecal bile acids were quantified. Cecal microbiota were analyzed by PCR amplification of the V3 and V4 regions of 16S rRNA genes and sequenced using a MiSeq System. Additionally, the cecal short-chain fatty acid profile was assessed. The results revealed that the liver lipid and triglyceride contents were significantly lower (p<0.01) and amounts of bile acids and lipids in the feces were significantly higher in the PGA group than in the Con group. The cecal butyric acid concentration was observed to be significantly higher in the PGA group than in the Con group. Principal component analysis of the cecal microbiota revealed that the PGA and Con groups were distinct. The ratio of Firmicutes/Bacteroidetes was found to be significantly low in the PGA mice. The results revealed a significantly higher relative abundance of Lachnospiraceae (p<0.05) and significantly lower relative abundance of Coriobacteriaceae (p<0.01) in the PGA group. Analysis of the correlation between bacterial abundance and liver lipids, cecal short-chain fatty acids, fecal lipids, and fecal bile acids suggested that intestinal microbiota can be categorized into different types based on lipid metabolism. Hepatic lipid accumulation typically facilitates the onset of nonalcoholic fatty liver disease (NAFLD). Our findings suggest that high-γ-PGA natto is a beneficial dietary component for the prevention of NAFLD.

The application of restriction landmark genome scanning method for surveillance of non-mendelian inheritance in f(1) hybrids.

We analyzed inheritance of DNA methylation in reciprocal F(1) hybrids (subsp. japonica cv. Nipponbare x subsp. indica cv. Kasalath) of rice (Oryza sativa L.) using restriction landmark genome scanning (RLGS), and detected differing RLGS spots between the parents and reciprocal F(1) hybrids. MspI/HpaII restriction sites in the DNA from these different spots were suspected to be heterozygously methylated in the Nipponbare parent. These spots segregated in F(1) plants, but did not segregate in selfed progeny of Nipponbare, showing non-Mendelian inheritance of the methylation status. As a result of RT-PCR and sequencing, a specific allele of the gene nearest to the methylated sites was expressed in reciprocal F(1) plants, showing evidence of biased allelic expression. These results show the applicability of RLGS for scanning of non-Mendelian inheritance of DNA methylation and biased allelic expression.

Inheritance and alteration of genome methylation in F1 hybrid rice.

We analyzed the inheritance of DNA methylation in the first filial generation(F1) hybrid of Oryza sativa L. ("Nipponbare"x"Kasalath") by restriction landmark genome scanning (RLGS). Most parental RLGS spots were found in the F1, but eight spots (4%) showed abnormal inheritance: seven of the eight spots were missing in the F1, and one was newly detected in the F1. Here we show demethylation at restriction enzyme sites in the F1. We also found a candidate site of stable heterozygous methylation in the genome. These results show the applicability of the RLGS method for analysis of the inheritance and alteration of methylation in F1 hybrid plants.