Sake is made from steamed rice, malted rice, and water. Sake production begins with the preparation of a small-scale starter (moto); the quality of moto significantly influences the flavor and richness of sake. In the traditional starter, yamahai-moto, the growth of naturally occurring lactic acid bacteria represses the putrefactive micro-organisms, whereas in the modern starter, sokujo-moto, this is achieved by adding lactic acid. In this study, the successive change in bacterial flora of yamahai-moto was analyzed by pyrosequencing 16S ribosomal RNA genes. Lactobacillus was dominant throughout the process (93-98%). Nitrate-reducing bacteria that have been generally assumed to be the first colonizers of yamahai-moto were scarcely found in the early stage, but Lactobacillus acidipiscis dominated. Lactobacillus sakei drastically increased in the middle stage. This is the first report, though one case study, to show how the early stage microbiota in Japanese yamahai-moto is varyingly controlled without nitrate-reducing bacteria using next-generation sequencing.
The successful production of sake (Japanese rice wine) is brought about by drastic changes in microbial flora and chemical components during fermentation. In the traditional manufacturing process of sake starter (yamahai-moto), spontaneous growth of lactic acid bacteria suppresses inappropriate microorganisms and prepares the optimum environment for the alcohol fermentative yeast. In this study, we analyzed the changes in bacterial flora and chemical components of yamahai-moto. High-throughput next-generation sequencing (NGS) of the 16S ribosomal RNA gene V4 region revealed that various kinds of bacteria, including nitrate-reducing bacteria, existed in the early fermentation stage; however, Lactobacillus sakei then increased drastically to become dominant in the middle stage. Interestingly, this result was different from that obtained in the previous year at the same manufacturer; the early-stage major bacterium was Lactobacillus acidipiscis. Lactic acid, glucose, isomaltose, and total free amino acids increased throughout the fermentation process, which was attributable to the metabolism of L. sakei and the koji mold. It is noteworthy that significant ornithine accumulation and arginine consumption were observed from the middle to late stages. Thirty-eight percent of the L. sakei isolates from yamahai-moto exhibited significant ornithine production, indicating that the arginine deiminase pathway of L. sakei was working to survive the extremely low pH environment of the moto after the middle stage. This is the first report that includes concurrent analyses of the NGS-based bacterial flora and chemical components of yamahai-moto, providing further knowledge to help understand and improve the process of sake brewing.
A neutron resonance absorption spectrometer, DOG, has been installed at KENS, High Energy Accelerator Research Organization Neutron Source, which enables us to investigate the motions of a particular element by analyzing the line width of resonance absorption spectrum. We measured the temperature dependence of the effective temperature of Ta motion in TaS2 as well as in Ta metal using DOG. The effective temperatures extracted from the observed absorption spectrum agree well with the calculated values from the phonon density of states of Ta metal over a wide temperature range of 10 to 300 K. We also succeeded in measuring both the angular dependence and the temperature dependence of effective temperatures of Ta in a layer compound TaS2. Based on the temperature dependence of the effective temperature, the partial phonon density of states of Ta in TaS2 was discussed.
Conditional discrimination in the octopus (Octopus vulgaris) was studied using successive discrimination training. The experimental animals were divided into two groups, and a barrel-shaped white object (stimulus) was presented to each group. One of the groups was rewarded with food for responding to the stimulus, but only when the tank was aerated, whereas the other group was rewarded with food for responding to the stimulus when the aeration was switched off. The number of trials in which octopuses responded to the stimulus, and the latency of the responses, were significantly different between trials with the aeration on and trials with the aeration off, in both groups. Therefore, the octopuses learned to conditionally discriminate.
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