Yoshie Ueno

Glutamate Decarboxylase from Lactobacillus brevis: Activation by Ammonium Sulfate

In this study, the glutamate decarboxylase (GAD) gene from Lactobacillus brevis IFO12005 (Biosci. Biotechnol. Biochem., 61, 1168–1171 (1997)), was cloned and expressed. The deduced amino acid sequence showed 99.6% and 53.1% identity with GAD of L. brevis ATCC367 and L. lactis respectively. The His-tagged recombinant GAD showed an optimum pH of 4.5–5.0, and 54 kDa on SDS–PAGE. The GAD activity and stability was significantly dependent on the ammonium sulfate concentration, as observed in authentic GAD. Gel filtration showed that the inactive form of the GAD was a dimer. In contrast, the ammonium sulfate-activated form was a tetramer. CD spectral analyses at pH 5.5 revealed that the structures of the tetramer and the dimer were similar. Treatment of the GAD with high concentrations of ammonium sulfate and subsequent dilution with sodium glutamate was essential for tetramer formation and its activation. Thus the biochemical properties of the GAD from L. brevis IFO12005 were significantly different from those from other sources.

Lactobacillus senmaizukei sp. nov., isolated from Japanese pickle.

The taxonomic position of a lactic acid bacterium, strain L13(T), isolated from senmaizuke, a Japanese traditional pickle, was studied. This strain was a heterofermentative, facultatively anaerobic, Gram-positive, non-spore-forming, non-motile, rod-shaped bacterium. It produced dl-lactic acid from glucose. Phylogenetic analysis of its 16S rRNA gene sequence and physiological and biochemical characteristics indicated that the strain was a member of the genus Lactobacillus. Based on 16S rRNA gene sequence similarity, strain L13(T) was closely related to Lactobacillus hammesii CIP 108387(T) (98.9 %) and Lactobacillus parabrevis ATCC 53295(T) (98.5 %). In addition, the rpoA gene sequence of strain L13(T) was closely related to those of L. hammesii CIP 108387(T) (92.2 %) and L. parabrevis ATCC 53295(T) (92.0 %). However, DNA-DNA hybridization of strain L13(T) with these two strains revealed that strain L13(T) represents a separate genomic species. The DNA G+C content of strain L13(T) was 46 mol% and the peptidoglycan was of the A4alpha l-Lys-d-Asp type. Thus, these data indicate that strain L13(T) represents a novel species of the genus Lactobacillus, for which the name Lactobacillus senmaizukei is proposed. The type strain is L13(T) (=NBRC 103853(T)=TISTR 1847(T)).

Bio-functional pickles that reduce blood pressure of rats

Addition of γ-aminobutyric acid (GABA) and angiotensin converting enzyme (ACE)-inhibitory peptides to the pickles was studied in order to develop a new type of pickles that reduce blood pressure. Based on the outcome of these studies, a new type of fermentation bed composed of rice bran and white miso has been successfully developed. The advantage of such pickles is that they not only contain both GABA and ACE-inhibitory peptides, but also that their taste and flavor are excellent, with colors close to the original ones. The new type of pickles could temporarily reduce blood pressure in two types of rats, spontaneously hypertensive rats and NaCl-sensitive model rats. Thus, the newly developed pickles appear to be beneficial for pickle business. Graphical Abstract The newly developed pickles with GABA and ACE-inhibitory peptides could temporarily reduce blood pressure of hypertensive rats, which is beneficial for pickle business.

Further evidence that a new type of Japanese pickles reduce the blood pressure of spontaneously hypertensive rats

A new type of pickles (nukazuke) that contain GABA and angiotensin converting enzyme-inhibitory peptides and that reduce blood pressure of rats was studied further. Seven kinds of nukazuke forcefully administrated orally for one day reduced temporarily the blood pressure of spontaneously hypertensive rats. In addition, a fermented shougoin daikon administrated freely for 4 weeks did not increase the blood pressure of the rats, but suppressed it throughout the experiment. Taken together with previous data (Oda et al., Biosci. Biotechnol. Biochem., 2014) it was concluded that the nukazuke could reduce the blood pressure of spontaneously hypertensive rats. Thus, the newly developed functional pickles appear to be beneficial for pickles business. Graphical Abstract A new type of nukazuke administrated for 4 weeks did not increase the blood pressure of spontaneously hypertensive rats, but suppressed it throughout the experiment.