Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 77 , Issue 4
Showing 1-40 articles out of 40 articles from the selected issue
Analytical Chemistry Notes
Organic Chemistry Regular Papers
Biochemistry & Molecular Biology Regular Papers
  • Da-Hee SON, Mi-Hyun NAM, Chung-Oui HONG, Hye-Min SEOL, Jae-Eon YANG, Y ...
    2013 Volume 77 Issue 4 Pages 714-721
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Unripe green apples contain condensed tannins at 10 times higher levels than ripe apples. Tannin not only has strong antioxidant activity, but also an astringent property. In this study, we investigated the effects of green apple rind (GAR) extracts in reducing facial pores and sebum secretion. Among the GAR extracts, the 70% ethanol GAR extract showed the highest antioxidant activity and tannin content. Hence, it was further fractionated with different solvents. Among these rind solvent fractions, the ethyl acetate fraction of the extract (GAR-E) showed astringent activity. Additionally, it exhibited inhibitory effects on 5-α reductase, and induced type 1 collagen and involucrin synthesis. These results suggest that GAR-E can be applied in cosmetics to reduce facial pore size and sebum secretion.
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  • Satoko SHINJO, Yuji MIZOTANI, Etsu TASHIRO, Masaya IMOTO
    2013 Volume 77 Issue 4 Pages 729-735
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Supplementary material
    Endoplasmic reticulum (ER) stress, due to an accumulation of unfolded proteins in the ER, leads to a process known as the unfolded protein response (UPR). Since the several compounds used to induce UPR have different modes of action, their mechanisms of protein accumulation are thought to be different, but it is unclear whether these compounds can upregulate UPR target genes with similar kinetics. Hence, we sought to compare the expression patterns of nine UPR target genes induced by seven UPR-inducing compounds. Hierarchical clustering analysis revealed that the expression patterns of the UPR target genes induced by the seven compounds were classified into two clusters; cluster A (thapsigargin, tunicamycin, 2-deoxyglucose, and dithiothreitol) and cluster B (brefeldin A, monensin, and eeyarestatin I). Thus, this study suggests the existence of at least two types of UPR target gene expression profiles, which depend on the mode of action of the compounds.
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  • Evans MENACH, Kiyoshi YASUKAWA, Kuniyo INOUYE
    2013 Volume 77 Issue 4 Pages 741-746
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Neutral salts activate and stabilize thermolysin. We previously found that two single mutations, Asn116→Asp and Asp150→Glu, increase the activity of thermolysin. In the present study, we examined their effects on NaCl-induced activation and stabilization. In the hydrolysis of N-[3-(2-furyl)acryloyl]-glycyl-L-leucine amide, the relative activities (the ratios of the specificity constant, kcat/Km, at x M NaCl to that at 0 M NaCl) at 0.5–4.0 M NaCl of D150E and N116D/D150E were lower than those of wild-type thermolysin (WT) and N116D, respectively. In thermal inactivation at 70 °C, the relative stabilities (the ratios of the first-order rate constant, kobs, at 0 M NaCl to that at x M NaCl) at 0.5–4.0 M NaCl of D150E and N116D/D150E were lower than those of WT and N116D, respectively. These results indicate that unlike Asn116→Asp, Asp150→Glu reduced NaCl-induced activation and stabilization, suggesting that the binding of ions with certain residues of thermolysin is involved in the activation and stabilization.
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  • Takafumi YAMASHINO, Saori YAMAWAKI, Emi HAGUI, Hanayo UEOKA-NAKANISHI, ...
    2013 Volume 77 Issue 4 Pages 747-753
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Supplementary material
    During the last decade, significant research progress in the study of Arabidopsis thaliana has been made in defining the molecular mechanism by which the plant circadian clock regulates flowering time in response to changes in photoperiod. It is generally accepted that the clock-controlled CONSTANS (CO)-FLOWERING LOCUS T (FT)-mediated external coincidence mechanism underlying the photoperiodic control of flowering time is conserved in higher plants, including A. thaliana and Oryza sativa. However, it is also assumed that the mechanism differs considerably in detail among species. Here we characterized the clock-controlled CO-FT pathway in Lotus japonicus (a model legume) in comparison with that of A. thaliana. L. japonicus has at least one FT orthologous gene (named LjFTa), which is induced specifically in long-days and complements the mutational lesion of the A. thaliana FT gene. However, it was speculated that this legume might lack the upstream positive regulator CO. By employing L. japonicus phyB mutant plants, we showed that the photoreceptor mutant displays a phenotype of early flowering due to enhanced expression of LjFTa, suggesting that LjFTa is invovled in the promotion of flowering in L. japonicus. These results are discussed in the context of current knowledge of the flowering in crop legumes such as soybean and garden pea.
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  • Xiaoliang PANG, Kosuke TASHIRO, Rieko EGUCHI, Nobukazu KOMATSU, Tetsur ...
    2013 Volume 77 Issue 4 Pages 766-770
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Haptoglobin (Hp) is a well-known acute-phase protein that possibly has influence on tumors through the immune response. This study was conducted to evaluate the correlation between Hp expression and the effect of treatment by cancer peptide vaccines in advanced castration-resistant prostate cancer (CRPC) patients. Hp expression was measured by RT-PCR using peripheral blood mononuclear cells (PBMCs) collected from advanced CRPC patients, who were divided into two groups: long-term survivors and short-term survivors. Before cancer peptide vaccination (pre-vaccination), Hp expression was almost same in the two groups, but after cancer peptide vaccination (post-vaccination), Hp expression was higher in short-term survivors, suggesting that Hp expression in the PBMCs increased in short-term survivors after treatment by cancer peptide vaccines. Our results suggest that Hp expression level in the PBMCs can serve as a prognostic biomarker in treatment by cancer peptide vaccine in advanced CRPC patients.
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  • Natsuki MATSUSHITA, Sachi MATSUSHITA, Satoshi HIRAKAWA, Shigeki HIGASH ...
    2013 Volume 77 Issue 4 Pages 776-781
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Supplementary material
    RNA interference has been applied to the development of a method of silencing genes of interest. Short hairpin RNA (shRNA) expression vectors are useful in driving gene-silencing. Standard shRNA vectors produce a knockdown phenotype soon after transduction. An alternative strategy for conditional gene knockdown would be useful to investigate gene functions in a time-dependent manner. In this study, we developed an inducible gene knockdown system based on lentivirus-mediated gene transfer. A single lentivirus vector capable of inducible expression of a designed microRNA-based shRNA was generated using a tetracycline-dependent transactivation system. The lentiviral vector facilitated doxycycline-dependent inducible knockdown specific to the target gene. Withdrawal of doxycycline after transient treatment resulted in complete recovery of target gene expressions to normal levels. Thus the single lentiviral vector developed in this study should be a powerful tool for doxycycline-dependent inducible and reversible RNA interference in molecular genetic studies.
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  • Hideaki SHIRAISHI, Yosuke TABUSE
    2013 Volume 77 Issue 4 Pages 782-788
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    The degradation of foreign DNAs by restriction enzymes in an edible cyanobacterium, Arthrospira platensis, is a potential barrier for gene-transfer experiments in this economically valuable organism. We overproduced in Escherichia coli the proteins involved in a putative restriction-modification system of A. platensis NIES-39. The protein produced from the putative type II restriction enzyme gene NIES39_K04640 exhibited an endonuclease activity that cleaved DNA within the sequence 5′-CTGCAG-3′ between the A at the fifth position and the G at the sixth position. We designated this enzyme AplI. The protein from the adjacent gene NIES39_K04650, which encodes a putative DNA (cytosine-5-)-methyltransferase, rendered DNA molecules resistant to AplI by modifying the C at the fourth position (but not the C at the first position) in the recognition sequence. This modification enzyme, M.AplI, should be useful for converting DNA molecules into AplI-resistant forms for use in gene-transfer experiments. A summary of restriction enzymes in various Arthrospira strains is also presented in this paper.
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  • Koji YAMAGUCHI, Yusuke NAKAMURA, Kazuya ISHIKAWA, Yuya YOSHIMURA, Seij ...
    2013 Volume 77 Issue 4 Pages 796-801
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Xanthomonas oryzae delivers effector proteins into host cells through a type III secretion system to inhibit host immune responses, but how these effectors suppress host immunity is largely unknown. Here we found that Xoo2875, one of the effectors of X. oryzae, strongly inhibited host resistance to X. oryzae. Transgenic rice plants expressing Xoo2875 exhibited semi-dwarfism and a reduction in Brassinolide-dependent laminar inclination, characteristics of brassinosteroid (BR)-insensitive mutants caused by mutations of the BR receptor. A yeast two-hybrid experiment indicated that Xoo2875 interacted with OsBAK1, an essential component of both microbe-associated molecular patterns (MAMPs) and BR receptors, suggesting that the virulent activity of Xoo2875 is mediated by inhibition of OsBAK1. Expression of Xoo2875 in Arabidopsis cells activated host immune responses, suggesting the presence of intracellular immune receptors that recognize Xoo2875. Because Xoo2875 homologs are highly conserved in Xanthomonas species, the development of Xoo2875-induced immunity is probably a useful strategy to avoid pathogen invasion.
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  • Eiji ISHII, Yoko EGUCHI, Ryutaro UTSUMI
    2013 Volume 77 Issue 4 Pages 814-819
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    The PhoQ/PhoP two-component signal transduction system in Escherichia coli is activated by SafA, a small membrane protein that modifies the PhoQ histidine kinase. The SafA C-terminal domain (41–65 aa) interacts directly with the sensory domain of PhoQ at the periplasm. We used in vitro and in vivo strategies to elucidate the way SafA modifies the PhoQ/PhoP phosphorelay system. First, the enzymatic activities of membranes from cells overexpressing PhoQ and cells expressing both PhoQ and SafA were compared in vitro. Increased autophosphorylation of PhoQ was observed in the presence of SafA, but it did not increase the dephosphorylation of phospho-PhoP by PhoQ. In addition, SafA increased the phospho-PhoP level on the phosphotransfer assay. We confirmed that induction of SafA results in an accumulation of phospho-PhoP in vivo by the Phos-tag system. Our results suggest that the accumulation of phospho-PhoP is linked to activation of PhoQ autophosphorylation by SafA.
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Biochemistry & Molecular Biology Notes
Food & Nutrition Science Regular Papers
  • Tomomi KOUGUCHI, Takashi OHMORI, Muneshige SHIMIZU, Yoshihisa TAKAHATA ...
    2013 Volume 77 Issue 4 Pages 691-696
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    We investigated the effects of a chicken collagen hydrolysate (CCH) on the circulation system in humans. A total of 58 subjects with either mild hypertension (systolic blood pressure (SBP) of 140–159 mmHg or diastolic blood pressure (DBP) 90–99 mmHg) or high-normal blood pressure (SBP 130–139 mmHg or DBP 85–89 mmHg) were assigned to two groups, one involving a placebo and the other, the test food (including CCH of 2.9 g/d). The parameters related to each subject's circulation system were monitored over the study period of 18 weeks. The Δbrachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness and marker of vascular damage, was significantly lower in the test food group than in the placebo group during the treatment period. The blood pressure in the test food group was also significantly lower than that in the placebo group, while the serum nitrogen oxide was higher in the test food group after the treatment. These results suggest that CCH exerted modulatory effects on the human circulation system.
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  • Tae-Jin SHIM, Tae Myoung KIM, Ki Chang JANG, Jee-Yeon KO, Dae Joong KI ...
    2013 Volume 77 Issue 4 Pages 697-705
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Golden gelatinous sorghum (GGS) is rich in phytochemicals and anti-oxidants. We investigated the toxicity and anti-inflammatory properties of a GGS extract. We observed no toxic effects after a daily dose of up to 5000 mg/kg body weight of the GGS extract administered orally to rats for 14 d. The exposure of mice ears to 12-O-tetradecanoylphorbol-13-acetate (TPA) caused a marked increase in ear thickness, which was significantly inhibited by treating with the GGS extract; this inhibition of inflammatory response was clearly confirmed by a histological analysis. The TPA-induced mice ear edema model, indicated that treating with the GGS extract inhibited the expression levels of such inflammatory mediators as cyclooxygenase-2 and inducible nitric oxide synthase. The nitric oxide level in lipopolysaccharide (LPS)-induced Raw264.7 cells in vitro was lower in the GGS extract-treated group than in the LPS-only treated group. These results suggest that sorghum would be a safe, nontoxic product, and that the GGS extract possessed significant anti-inflammatory activity.
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  • Shigeaki UENO, Takumi KATAYAMA, Takae WATANABE, Kanako NAKAJIMA, Mayum ...
    2013 Volume 77 Issue 4 Pages 706-713
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    The effects were investigated of the glutamic acid (Glu) substrate concentration on the generation and kinetics of γ-aminobutyric acid (GABA) in soybeans treated under high hydrostatic pressure (HHP; 200 MPa for 10 min at 25 °C). The conversion of Glu to GABA decreased with increasing initial Glu concentration in the soybeans. The crude glutamate decarboxylase (GAD) obtained from the HHP-treated soybeans showed substrate inhibition. The GABA production rate in the HHP-treated soybeans fitted the following substrate inhibition kinetic equation: v0=(VmaxS0)/(Km+S0+(S0)2/Ki). The Km value for the HHP-treated soybeans was significantly higher than that of the untreated soybeans. The Km values in this study show the affinity between Glu and GAD, and indicate that the HHP-treated soybeans had lower affinity between Glu and GAD than the untreated soybeans. GAD extracted from the HHP-treated soybeans showed a similar value to that in the HHP-treated soybeans. The intact biochemical system was so damaged in the HHP-treated soybeans that it showed substrate inhibition kinetics similar to that of the extracted GAD. The combination of HHP and precursor feeding proved to be a novel tool that can be used to increase the concentration of a target component.
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  • Seolhyun PARK, Yoo-Sun KIM, Hyun-Ah LEE, Yunsook LIM, Yuri KIM
    2013 Volume 77 Issue 4 Pages 722-728
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    A neuroblastoma is an extracranial solid tumor diagnosed in childhood. Since tumor metastasis is the main cause of death for most neuroblastoma patients, an understanding of the mechanisms that modulate cancer cell invasion is a key to developing more effective chemotherapeutic agents. In the current study, we examined to determine whether mulberry leaf (ML) extract effectively inhibits the invasion potential of neuroblastoma cells in vitro. ML extract was found to suppress cell invasiveness as well as the activity and expression of matrix metalloproteinase-2 (MMP-2) under both normoxia and hypoxia in neuroblastoma. ML extract downregulated the expression of hypoxia-inducible factor-1α (HIF-1α), a well-known regulator of tumor metastasis, and its downstream targets, vascular endothelial growth factor (VEGF) and glucose transporter-1 (GLUT-1). Taken together, these results suggest that ML extract has chemotherapeutic effects on neuroblastoma cells by regulating invasion potential, thereby controlling the metastasis of neuroblastomas.
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  • Tatsuya MORIYAMA, Miyako YANAGIHARA, Erika YANO, Goro KIMURA, Mariko S ...
    2013 Volume 77 Issue 4 Pages 789-795
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Royal jelly (RJ), the exclusive food for queen bees, is taken as a dietary supplement because it is highly rich in nutrients. However, RJ is known to induce an anaphylactic response in some individuals. We evaluated in the present study the hypoallergenicity of alkaline protease-treated RJ in vitro and in vivo. We first confirmed that this treated RJ contained the same levels of vitamins, minerals and specific fatty acid as in untreated RJ. We then showed that the IgE-binding capacity of the treated RJ was very significantly reduced by conducting in vitro assays of the blood from RJ-sensitive patients. An in vivo skin-prick test on the RJ-sensitive patients also showed that, in the majority of the patients (3 out of 4 tested), the treated RJ did not evoke any allergenic response. It is thus advantageous to prepare hypoallergenic RJ by a protease enzyme treatment for its safe consumption.
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  • Sumiko NAKAMURA, Ryosuke TSUSHIMA, Ken'ichi OHTSUBO
    2013 Volume 77 Issue 4 Pages 820-831
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Supplementary material
    We developed a method for the preparation of template DNAs for polymerase chain reaction (PCR) from beer. We improved the method by (i) lyophilizing and pulverizing the beer to concentrate DNAs, (ii) decomposition of polysaccharides and proteins so as not to inhibit DNA extraction by the use of heat-resistant amylase and proteinase K, (iii) separation of template DNA by purification using 70% EtOH extraction and isopropyl alcohol precipitation, and (iv) the use of magnetic beads to purify DNA. We developed suitable 7 STS (sequence-tagged site) primers related to beer quality for PCR, and it proved possible to identify 16 dominant malting barley cultivars and 22 kinds of beers. To digitize the results of PCR, discriminative DNA bands were binarized as 0 (disappeared) or 1 (appeared) and subjected to multiple regression analysis. Estimation formulae for the quality of beer were developed using the above-mentioned independent variables based on the results of PCR against dependent variables related to the qualities of beer, including foam stability, bitterness, sourness and astringency. These equations showed multiple regression coefficients of 0.93, 0.82, 0.87, and 0.87 for calibration.
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Food & Nutrition Science Notes
Food & Nutrition Science Communication
  • Yoko YAMASHITA, Masaaki OKABE, Midori NATSUME, Hitoshi ASHIDA
    2013 Volume 77 Issue 4 Pages 888-891
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Procyanidins are oligomers and polymers of flavan-3-ols consisting of (−)-epicatechin subunits. In this study, we isolated and purified dimeric, trimeric and tetrameric procyanidins from cacao liquor and investigated their influence on the “incretin effect” as compared to the monomer, (−)-epicatechin in mice. Cinnamtannin A2 specifically increased the glucagon-like peptide-1 (GLP-1) and insulin secretion levels in the plasma after 60 min administration. As evidence of the action of insulin, activation of insulin receptor and insulin receptor substrate-1 was observed in the soleus muscle. These results indicate that the intake of cinnamtannin A2 may improve hyperglycemia through an incretin-like effect, accompanied by activation of the insulin-signaling pathway.
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Microbiology & Fermentation Technology Regular Papers
  • Kannan PONNUSAMY, Sarah LEE, Choong Hwan LEE
    2013 Volume 77 Issue 4 Pages 683-690
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    The microbial community and the metabolites of barley nuruk were studied to determine the time-dependent correlation between the fermentation of microbes and metabolites. Samples were analyzed by a polyphasic approach based on culture-dependent, culture-independent (PCR-DGGE and qPCR analysis), and metabolite analysis using GC-MS. Barley nuruk consists of varying amounts of bacteria, yeasts, and molds. The PCR-DGGE results showed that only one phylotype, Aspergillus oryzae, was predominant throughout fermentation, reaching a maximum on day 9. The bacterial load was higher on day 6 of fermentation, and then gradually decreased because of increased fungal activity. The shift in fungal and bacterial diversity observed by DGGE was further confirmed by qPCR analysis. In addition, microbes closely related to Pantoea agglomerans and Saccharomycopsis fibuligera appeared to play key roles in the fermentation of barley nuruk. GC-MS analysis combined with multivariate analysis, including PCA, PLS-DA, and OPLS-DA, showed fermentation time-dependent metabolite patterns. A total of 21 metabolites, including organic acids, amino acids, sugars, and sugar alcohols, were identified. In particular, glycerol, malic acid, fructose, glucose, sucrose, and maltose were produced at the early fermentation stages (0–6 d), whereas glutamine, aspartic acid, glutamic acid, mannitol, and xylitol were produced during the latter stages of fermentation (9–18 d). Mixed culture fermentation was found throughout the natural fermentation of barley nuruk starter. Most likely, A. oryzae had a major role in saccharification, along with other mixed cultures.
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  • Yasushi TANI, Kaori NAKAMURA, Ryota SAWA, Masashi NISHIO, Shigeki SAIT ...
    2013 Volume 77 Issue 4 Pages 754-759
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Glycosphingolipids (GSLs) are essential membrane components of eukaryotic cells. Recently, a new type of fungal neogala-series GSL was identified in aureobasidin A-resistant fungi. In this study, we analyzed GSLs from four pathogenic fungal strains belonging to the order Hypocreales, and found that Mariannaea elegans contained both acidic GSLs and neutral GSLs with mono- and di-saccharides. The structures of the neutral GSLs of M. elegans were determined by compositional sugar, fatty acid, and sphingoid analyses by GC/MS, MALDI time-of-flight/MS, and 1H NMR. The ceramide moiety of Glcβ1-Cer consisted mainly of the 2-hydroxylated C18:0-fatty acid 9-methyl-octadeca-4-sphinganine or 9-methyl-octadeca-4,8-sphingadienine. In contrast, the ceramides of Galβ1-6Galβ1-Cer and Glc1-6Galβ1-Cer consisted mainly of saturated 2-hydroxylated C24:0-fatty acids and C18:0-phytosphingosine. To our knowledge, Glc1-6Galβ1-Cer is a novel GSL in fungi, and M. elegans is the first example of an aureobasidin A-sensitive fungus that possesses fungal neogala series GSLs.
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  • Kenji YAMAGISHI, Toshiyuki KIMURA, Takashi WATANABE
    2013 Volume 77 Issue 4 Pages 771-775
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Supplementary material
    Cyathus stercoreus has a superior ability to increase the cellulase saccharification yields of rice straw under biological pretreatment. As a first step to improve the biological pretreatment efficiency of C. stercoreus further, a new gene transformation system was constructed. Uracil auxotrophic mutant uv-180 was generated as host strain by ultraviolet radiation. It was transformed using plasmid pGE containing the orotate phosphoribosyltransferase (CsURA5) and enhanced green fluorescent protein (egfp). Many transformants exhibited strong fluorescence, indicating successful genetic transformation. An intron was needed for the expression of egfp. The EGFP fluorescence intensities of the three transformants did not decay even after subculturing on uracil-containing semisolid medium 5 times, suggesting that the transformed plasmids were stably retained in the absence of selective pressure.
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  • Shigeki KADA, Atsushi ISHIKAWA, Yoshifumi OHSHIMA, Ken-ichi YOSHIDA
    2013 Volume 77 Issue 4 Pages 802-809
    Published: April 23, 2013
    Released: April 23, 2013
    [Advance publication] Released: April 07, 2013
    JOURNALS FREE ACCESS
    Natto is a traditional Japanese food made from soybeans fermented by natto starter strains of Bacillus subtilis natto. It has been suggested that extracellular protease activity released by the bacteria are involved in the production of poly-γ-glutamate (γ-PGA) during natto fermentation. One of the natto starters, strain r22, possesses at least seven genes, each of which encoded an extracellular protease orthologous to its counterpart in B. subtilis 168, aprE, bpr, epr, mpr, nprE, vpr, and wprA, but it was found to lack nprB. Inactivating the aprE ortholog alone resulted in a severe decrease in γ-PGA production and in the total extracellular protease activity. The defect in γ-PGA production of the mutant lacking the aprE ortholog was complemented when the medium was supplemented with sufficient glutamate. These results suggest that the alkaline serine protease encoded by aprE plays an indispensable role in supplying materials to produce γ-PGA. On the other hand, simultaneous inactivation of all the protease genes except for aprE did not significantly affect either γ-PGA production or total protease activity.
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Microbiology & Fermentation Technology Note
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