Nukadoko is a fermented rice bran bed traditionally used for pickling vegetables in Japan. To date, the production of both homemade and commercial nukadoko has depended on natural fermentation without using starter cultures. Spices, Japanese pepper, and red pepper, are added to nukadoko empirically, but the functions of spices in nukadoko have not been fully elucidated. To investigate the effects of Japanese pepper and red pepper on nukadoko fermentation, we compared the chemical and microbiological changes during 2 months of fermentation of a laboratory model nukadoko with or without spices. The successive pH values and colony counts in the first 10 days showed that the spices promoted lactic acid bacteria (LAB) growth and fermentation in the nukadoko niche. The successive bacterial communities during natural fermentation of nukadoko were carefully monitored by pyrotag 16S rRNA analysis, and the effect of spices on the development and maintenance of the nukadoko microbiota was investigated. It was shown that addition of Japanese peppers and red peppers shortened the pre-lactic acid fermentation phase, during which Staphylococcus saprophyticus grew dominantly, and promoted the development of a microbiota that LAB dominated. Notably, the growth of the dominant LAB, Pediococcus pentosaceus, was improved by adding either Japanese pepper or red pepper. The differences in the LAB species, which were associated with the differences in chemical composition of the nukadoko, were dependent on the type of pepper used. We conclude that the spices used can affect the bacterial community and modulate its metabolic profile in nukadoko.

View full abstract

We investigated the variation in immunological properties of the extracellular polysaccharides (EPSs) produced by different Lactobacillus delbrueckii strains as well as that of their monosaccharide composition. The monosaccharide composition of each EPS produced by L. delbrueckii strains, as determined by thin layer chromatography (TLC), showed an appreciable variation in a strain-dependent manner, which could be broadly assigned to 4 TLC groups. Meanwhile, the immunological properties of the EPSs produced by 10 L. delbrueckii strains were evaluated in a semi-intestinal model using a Transwell co-culture system, which employed human intestinal epithelial Caco-2 cells on the apical side and murine macrophage RAW264.7 cells on the basolateral side. Each EPS was added to the apical side to allow direct contact with Caco-2 cells and incubated for 6 hr. After incubation, the amounts of TNF-α and several cytokines that had been released by either RAW264.7 or Caco-2 cells were then quantified by cytotoxic activity on L929 cells or the RT-PCR method. It was found that the EPS-stimulated RAW264.7 cells express different profiles of cytokine production via Caco-2 cells but that the profile difference could not be related to the above TLC grouping. The evidence suggests that the EPSs of L. delbrueckii strains are diverse not only in their biochemical structure but also in their immunological properties.

View full abstract

Birds were given a new formulation of the Bacillus amyloliquefaciens B-1895 solid-state fermented soybean that retained the spores of the aforementioned organism. Mass dynamics, feed flow rate and broiler performance were observed to evaluate the efficacy of the formulation. At each time point, the live mass was greater than that of the control group, reaching a difference of 7–8% by day 28. A difference of 5.3–8.8% was observed in feed conversion per kilogram live mass (1.97 kg in the controls as compared with 1.81–1.87 kg in experimental groups). This indicates a positive effect of the B. amyloliquefaciens B-1895 formulation on the live mass of broilers as well as on feed consumption.

View full abstract