Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 74 , Issue 12
Showing 1-39 articles out of 39 articles from the selected issue
Award Reviews
  • Katsunori TANAKA
    2010 Volume 74 Issue 12 Pages 2367-2373
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    There is mounting evidence that replication defects are the major source of spontaneous genomic instability in cells, and that S-phase checkpoints are the principal defense against such instability. The S-phase checkpoint mediator protein Mrc1/Claspin mediates the checkpoint response to replication stress by facilitating phosphorylation of effector kinase by a sensor kinase. In this review, the multiple functions and the regulation of the S-phase checkpoint mediator are discussed.
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  • Shinya FUSHINOBU
    2010 Volume 74 Issue 12 Pages 2374-2384
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Bifidobacteria have many beneficial effects for human health. The gastrointestinal tract, where natural colonization of bifidobacteria occurs, is an environment poor in nutrition and oxygen. Therefore, bifidobacteria have many unique glycosidases, transporters, and metabolic enzymes for sugar fermentation to utilize diverse carbohydrates that are not absorbed by host humans and animals. They have a unique, effective central fermentative pathway called bifid shunt. Recently, a novel metabolic pathway that utilizes both human milk oligosaccharides and host glycoconjugates was found. The galacto-N-biose/lacto-N-biose I metabolic pathway plays a key role in colonization in the infant gastrointestinal tract. These pathways involve many unique enzymes and proteins. This review focuses on their molecular mechanisms, as revealed by biochemical and crystallographic studies.
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Analytical Chemistry Note
  • Tomonori INOUE, Yasushi NAGATOMI, Tomohisa KINAMI, Atsuo UYAMA, Naoki ...
    2010 Volume 74 Issue 12 Pages 2518-2522
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Moromi (the fermented mash) of “mugi shochu” that had been artificially contaminated with pesticides was distilled to elucidate the fate of pesticides in the distillation process. The pesticides residing in the distillate were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Of the analyzed pesticides (249 compounds), 89% were not detected in the distillate, showing that the distillation process minimized the risk of pesticide contamination.
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Analytical Chemistry Communication
  • Mika SHIRASU, Kouki FUJIOKA, Satoshi KAKISHIMA, Shunji NAGAI, Yasuko T ...
    2010 Volume 74 Issue 12 Pages 2550-2554
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    The titan arum, Amorphophallus titanum, is a flowering plant with the largest inflorescence in the world. The flower emits a unique rotting animal-like odor that attracts insects for pollination. To determine the chemical identity of this characteristic odor, we performed gas chromatography-mass spectrometry-olfactometry analysis of volatiles derived from the inflorescence. The main odorant causing the smell during the flower-opening phase was identified as dimethyl trisulfide, a compound with a sulfury odor that has been found to be emitted from some vegetables, microorganisms, and cancerous wounds.
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Organic Chemistry Notes
Biochemistry & Molecular Biology Regular Papers
  • Chae Woo LIM, Ji Young PARK, Suk Ha LEE, Cheol Ho HWANG
    2010 Volume 74 Issue 12 Pages 2396-2404
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Supplementary material
    Legumes have the ability to form root nodules that fix atmospheric nitrogen through a symbiotic interaction with nitrogen-fixing bacteria. As a first step in dissecting the molecular process of nodulation, proteome reference maps of soybean roots and nodules were constructed. Time course analysis revealed that the transition from root to nodule was accompanied with downregulation of defense-response related proteins, including Mn-superoxide dismutase, peroxidase (Prx), PR10, and stress-induced protein, leading to the initiation of a symbiotic interaction between the two partners. Following nitrogenase biosynthesis, the host plant cooperated with the rhizobia to fix atmospheric nitrogen under microaerobic conditions via expression of leghemoglobins and antioxidant proteins. Comparative proteome analysis indicated lower expression of malate dehydrogenase (MDH), leghemoglobins and nitrogenase in the nodule development of the supernodulation mutant, SS2-2, as compared to the wild type, indicating that SS2-2 forms functionally immature nodules in higher numbers with the lower activity of nitrogen fixation.
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  • Dai-ichiro KATO, Hiromitsu YOSHIDA, Masahiro TAKEO, Seiji NEGORO, Hiro ...
    2010 Volume 74 Issue 12 Pages 2405-2412
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    We succeeded in the purification and gene cloning of a new enzyme, α-methyl carboxylic acid deracemizing enzyme 1 (MCAD1) from Brevibacterium ketoglutamicum KU1073, which catalyzes the (S)-enantioselective thioesterification reaction of 2-(4-chlorophenoxy)propanoic acid (CPPA). The cloned gene of MCAD1 contained an ORF of 1,623 bp, encoding a polypeptide of 540 amino acids. In combination with cofactors ATP, coenzyme A (CoASH), and Mg2+, MCAD1 demonstrated perfect enantioselectivity toward CPPA. The optimal pH and temperature for reaction were found to be 7.25 and 30 °C. Under these conditions, the Km and kcat values for (S)-CPPA were 0.92±0.17 mM and 0.28±0.026 s−1 respectively. The results for substrate specificity revealed that MCAD1 had highest activity toward fatty acid tails with a medium chain-length (C8). This result indicates that MCAD1 should be classified into a family of medium-chain acyl-CoA synthetase. This novel activity has never been reported for this family.
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  • Ya-Qin WEN, Jing-Ming LI, Zhen-Zhen ZHANG, Yan-Fang ZHANG, Qiu-Hong PA ...
    2010 Volume 74 Issue 12 Pages 2413-2417
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    L-Idonate dehydrogenase (L-IdnDH) is the only known enzyme of the tartaric acid (TA) biosynthetic pathway in grape berries. Previous studies on this enzyme only focused on the transcriptional expression of this gene. Here, the antibody against L-IdnDH was prepared by cloning the full-length cDNAs of VvIdnDH from grape berries, highly expressing fusion protein in Escherichia coli cells, and then immunizing rabbits. Expression of VvIdnDH at the transcriptional and translational levels in grape berries increased within 3 weeks after full bloom and then decreased, similarly to the trend for TA contents. Almost no VvIdnDH transcript was detected in the mature berries, but VvIdnDH protein was detectable. In the 21-d berries, this enzyme was largely located in the cytoplasm and a few in the cell wall, secondary cell wall, and chloroplast, whereas in the 60 berries, it was distributed mainly in the vacuole and cytoplasm.
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  • Isao OISHI
    2010 Volume 74 Issue 12 Pages 2426-2430
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Chicken primordial germ cells (PGCs) differentiate into germ cells in gonads. Because PGCs can be cloned and cultured maintaining germline competency, they are a good means of modifing the chicken genome, but the efficiency of plasmid transfection into PGCs is very low. In this study, I attempted to improve the efficiency of PGC transfection. Cultured PGCs were purified by Percoll density gradient centrifugation, and were then transfected with plasmid DNA. For transient transfection, the transfection efficiency increased more than 7-fold by the Percoll method. The efficiency of stable transfection of PGCs also increased significantly. The stable transfectants that were isolated by this method accumulated in the developing gonads after microinjection into bloodstream of chick embryos, indicating that gene transfection by Percoll purification did not alter the function of PGCs in vivo.
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  • Evans MENACH, Kiyoshi YASUKAWA, Kuniyo INOUYE
    2010 Volume 74 Issue 12 Pages 2457-2462
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    In the N-terminal domain of thermolysin, two polypeptide strands, Asn112-Ala113-Phe114-Trp115 and Ser118-Gln119-Met120-Val121-Tyr122, are connected by a short loop, Asn116-Gly117, to form an anti-parallel β-sheet. The Asn112-Trp115 strand is located in the active site, while the Ser118-Tyr122 strand and the Asn116-Gly117 loop are located outside the active site. In this study, we explored the catalytic role of Gly117 by site-directed mutagenesis. Five variants, G117A (Gly117 is replaced by Ala), G117D, G117E, G117K, and G117R, were produced by co-expressing in Escherichia coli the mature and pro domains as independent polypeptides. The production levels were in the order G117E > wild type > G117K, G117R > G117D. G117A was hardly produced. This result is in contrast to our previous one that all 72 active-site thermolysin variants were produced at the similar levels whether they retained activity or not (M. Kusano et al. J. Biochem., 145, 103–113 (2009)). G117E exhibited lower activity in the hydrolysis of N-[3-(2-furyl)acryloyl]-glycyl-L-leucine amide and higher activity in the hydrolysis of N-carbobenzoxy-L-aspartyl-L-phenylalanine methyl ester than the wild-type thermolysin. G117K and G117R exhibited considerably reduced activities. This suggests that Gly117 plays an important role in the activity and stability of thermolysin, presumably by affecting the geometries of the Asn112-Trp115 and Ser118-Tyr122 strands.
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  • Chie OTSUKA, Ikuko MINAMI, Kenji ODA
    2010 Volume 74 Issue 12 Pages 2463-2469
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Supplementary material
    Rice has evolved metabolic and morphological adaptations to low-oxygen stress to grow in submerged paddy fields. To characterize the molecular components that mediate the response to hypoxia in rice, we identified low-oxygen stress early response genes by microarray analysis. Among the highly responsive genes, five genes, OsHREF1 to OsHREF5, shared strong homology. They encoded small proteins harboring two EF-hands, typical Ca2+-binding motifs. Homologous genes were found in many land plants, including SlHREF in tomato, which is also strongly induced by hypoxia. SlHREF induction was detected in both roots and shoots of tomato plants under hypoxia. With the exception of OsHREF5, OsHREF expression was unaffected by drought, salinity, cold, or osmotic stress. Fluorescent signals of green fluorescent protein-fused OsHREFs were detected in the cytosol and nucleus. Ruthenium red, an inhibitor of intracellular Ca2+ release, repressed induction of OsHREF1-4 under hypoxia. The HREFs may be related to the Ca2+ response to hypoxia.
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  • Yota TATARA, Takahiro TERAKAWA, Takafumi UCHIDA
    2010 Volume 74 Issue 12 Pages 2480-2483
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    To determine the role of Pin1 in the neurotransmission pathway, Pin1-binding proteins in mouse brain extract were identified. The Pin1-binding proteins were extracted from mouse brain homogenate, and the trypsin-digested peptides were analyzed by nano-liquid chromatography tandem mass spectrometry (LC-MS/MS). Proteins that involve the neurotransmission pathway, such as synapsin I, synapsin II, and calcium/calmodulin-dependent protein kinase type II (CaMKII), were identified in a Mascot search. Pull-down and immunoprecipitation assay indicated that Pin1 binds CaMKII in a phosphorylation-specific manner. It was assumed that Pin1 participates in the neurotransmission pathway involving the phosphorylation signal by CaMKII.
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Biochemistry & Molecular Biology Notes
Biochemistry & Molecular Biology Communications
  • Atsushi KUNIHIRO, Takafumi YAMASHINO, Takeshi MIZUNO
    2010 Volume 74 Issue 12 Pages 2538-2541
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Supplementary material
    In Arabidopsis thaliana, plant growth, including elongation of hypocotyl is regulated in response to light conditions through circadian clock-controlled PHYTOCHROME-INTERACTING FACTORs PIF4 and PIF5. In this study, we found that these transcription factors were responsible not only for red light signaling through the phytochromes but also for blue light signaling in the photomorphogenic control of hypocotyl elongation. It is possible that plant hormone gibberellins play an important role in blue light signaling in part through PIF4/PIF5.
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  • Kai ISHIDA, Takafumi YAMASHINO, Hanayo NAKANISHI, Takeshi MIZUNO
    2010 Volume 74 Issue 12 Pages 2542-2545
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Supplementary material
    Physcomitrella patens, belonging to bryopsida, is a basal lineage of land plants. To gain insight into the diversification of the two-component system (TCS), which is widely conserved from prokaryotes to eukaryotes, we compiled TCS-associated genes by employing P. patens genome databases. The moss has a set of His-kinases (HKs), including homologs of the cytokinin- and ethylene-receptors in seed plants. In addition, it has a number of coding-sequences specifying unique HKs. We found evidence that a putative cytokinin-receptor HK in P. patans serves as a sensor for this hormone, and that the HK activity of a putative ethylene-receptor homolog is regulated by ethylene, as observed for Arabidopsis thaliana.
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Food & Nutrition Science Regular Papers
  • Yukihiro KOBAYASHI, Maki MIYAZAWA, Asuka KAMEI, Keiko ABE, Takashi KOJ ...
    2010 Volume 74 Issue 12 Pages 2385-2395
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    To determine the effects of mulberry (Morus alba L.) leaves on hyperlipidemia, we performed gene expression profiling of the liver. Rats were fed a high-fat diet and administered mulberry leaves for 7 weeks. Plasma triglyceride and non-esterified fatty acid levels were significantly lower in the rats treated with mulberry leaves as compared with the untreated rats. DNA microarray analysis revealed that mulberry leaves upregulated expression of the genes involved in α-, β- and ω-oxidation of fatty acids, mainly related to the peroxisome proliferator-activated receptor signaling pathway, and downregulated the genes involved in lipogenesis. Furthermore, treatment with mulberry leaves upregulated expression of the genes involved in the response to oxidative stress. These results indicate that consumption of fatty acids and inhibition of lipogenesis are responsible for the reduction in plasma lipids caused by mulberry administration. In addition, mulberry treatment maintains the body’s oxidative state at a low level despite enhancing fatty acid oxidation.
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  • Yan SHEN, Misato FUKUSHIMA, Yoshimasa ITO, Etsuko MURAKI, Takashi HOSO ...
    2010 Volume 74 Issue 12 Pages 2418-2425
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    It has long been believed that an intake of cinnamon (Cinnamomum zeylanicum) alleviates diabetic pathological conditions. However, it is still controversial whether the beneficial effect is insulin-dependent or insulin-mimetic. This study was aimed at determining the insulin-independent effect of cinnamon. Streptozotocin-induced diabetic rats were divided into four groups and orally administered with an aqueous cinnamon extract (CE) for 22 d. The diabetic rats that had taken CE at a dose of more than 30 mg/kg/d were rescued from their hyperglycemia and nephropathy, and these rats were found to have upregulation of uncoupling protein-1 (UCP-1) and glucose transporter 4 (GLUT4) in their brown adipose tissues as well as in their muscles. This was verified by using 3T3-L1 adipocytes in which CE upregulates GLUT4 translocation and increases the glucose uptake. CE exhibited its anti-diabetic effect independently from insulin by at least two mechanisms: i) upregulation of mitochondrial UCP-1, and ii) enhanced translocation of GLUT4 in the muscle and adipose tissues.
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  • Taiki MORI, Takeshi ISHII, Mitsugu AKAGAWA, Yoshimasa NAKAMURA, Tsutom ...
    2010 Volume 74 Issue 12 Pages 2451-2456
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    In this study, we investigated the relationship between the stability of catechins and their electrophilic reactivity with proteins. The stability of catechins was evaluated by HPLC analysis. Catechol-type catechins were stable in a neutral buffer, but pyrogallol-type catechins, such as (−)-epigallocatechin gallate (EGCg), were unstable. The electrophilic reactivity of catechins with thiol groups in a model peptide and a protein was confirmed by both mass spectrometry and electrophoresis/blotting with redox-cycling staining. In a comparison of several catechins, pyrogallol-type catechins had higher reactivity with protein thiols than catechol-type catechins. The instability and reactivity of EGCg were enhanced in an alkaline pH buffer. The reactivity of EGCg was reduced by antioxidants due to their ability to prevent EGCg autoxidation. These results indicate that the instability against oxidation of catechins is profoundly related to their electrophilic reactivity. Consequently, the difference in these properties of tea catechins can contribute to the magnitude of their biological activities.
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  • Kazuki MOCHIZUKI, Masaya SHIMADA, Yutaro TANAKA, Nanae FUKAYA, Toshina ...
    2010 Volume 74 Issue 12 Pages 2470-2474
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    β2 integrins (CD11s/CD18) promote the attachment of leukocytes to vascular endothelial cells. We performed in this study sucrose loading to rats with moderate postprandial hyperglycemia with/without once-daily dosing of the α-glucosidase inhibitor, miglitol, for 4 days under 4-h fasting conditions. The streptozotocin (STZ)-treated rats showed moderate postprandial hyperglycemia on days 1 and 4. The gene expression was higher for CD11a with fasting and 3-h postprandial on day 1, and with fasting on day 4, for CD11b with fasting on day 1 and 3-h postprandial on day 4, and for CD18 with fasting on days 1 and 4 in peripheral leukocytes from the STZ-treated rats than in peripheral leukocytes from the saline-treated rats. Miglitol reduced postprandial hyperglycemia and the gene expression of CD11a with fasting and of CD11b 3-h postprandial on day 4. These results indicate that inhibiting postprandial hyperglycemia reduced the mRNA expression of β2 integrins in peripheral leukocytes of moderately postprandial hyperglycemic rats.
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  • Yasuyuki TAKENAKA, Yasuhiro ARII, Hironori MASUI
    2010 Volume 74 Issue 12 Pages 2475-2479
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Approximately 40% of defatted perilla seeds consists of proteins which are primarily composed of globulin (84%). The amino acid profile of perilla proteins demonstrated balanced amounts of all essential amino acids, except for lysine. The molecular mass of the predominant globulin was estimated to be 340 kDa by gel filtration. This globulin was separated into three intermediary subunits (54, 57 and 59 kDa) by SDS–PAGE. It is suggested from these results that the globulin exists as a hexamer. A treatment with 50 mM dithiothreitol enabled the intermediary subunits to be separated into three acidic subunits (31–34 kDa) and four basic subunits (23–25 kDa). It is interesting that this subunit structure is the same as that of sesame α-globulin, despite them coming from different families. Compared to sesame α-globulin, the heat-induced gel of perilla globulin had better water-holding ability, despite it displaying the same degree of gel hardness.
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  • Sumiko NAKAMURA, Ken’ichi OHTSUBO
    2010 Volume 74 Issue 12 Pages 2484-2489
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    The physicochemical properties of rice flour and wheat flour influenced the oil uptake of tempura frying batter. Rice flour was better than wheat flour in the overall quality and crispness of the fried tempura batter. Rice flour resisted oil absorption more than wheat flour, and a higher level of apparent starch amylose and higher consistency/breakdown ratio of the pasting properties led to a lower oil uptake of the batter. Super hard EM10 rice showed the highest apparent amylose content and higher consistency/breakdown ratio than the other flour samples, the batter from EM10 revealing the lowest oil content after frying among all the batters examined. The apparent amylose content, consistency/breakdown ratio and oil absorption index are proposed as useful guides for oil absorption when frying from among the physicochemical properties that influence the oil content of fried batter. Our proposal for the “oil absorption index” could be a simple, although not perfect method for estimating the oil content of batter flour.
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Food & Nutrition Science Notes
Microbiology & Fermentation Technology Regular Papers
  • Zhemin ZHOU, Naoki TAKAYA, Hirofumi SHOUN
    2010 Volume 74 Issue 12 Pages 2431-2437
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    The fungus Fusarium oxysporum produces energy under hypoxic and anoxic conditions by denitrification (nitrate respiration) and ammonia fermentation respectively. Here we found that glucose repressed both of these metabolisms, whereas it supported another anoxic metabolism, hetero-lactic acid fermentation. Ammonia fermentation occurred only after the glucose present in the medium was metabolized to ethanol via alcohol fermentation. During this transition, clear diauxic growth was observed. Glucose regulated the activity of the enzymes involved in ammonia fermentation, hetero-lactic acid fermentation, and denitrification. Highest cell growth was supported by hetero-lactic acid fermentation, followed by denitrification and ammonia fermentation. These results indicate that the energy metabolisms of F. oxysporum are dependent not only on environmental O2 tension but also on the carbon source, and that ammonia fermentation is an adaptative mechanism acting physiologically as a secondary fermentative mechanism replacing the primary hetero-lactic acid fermentation.
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  • Osao ADACHI, Yoshitaka ANO, Emiko SHINAGAWA, Toshiharu YAKUSHI, Kazuno ...
    2010 Volume 74 Issue 12 Pages 2438-2444
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    The membrane fraction of Gluconobacter oxydans IFO 3244, involving membrane-bound quinoprotein quinate dehydrogenase and 3-dehydroquinate dehydratase, was immobilized into Ca-alginate beads. The Ca-alginate-immobilized bacterial membrane catalyzed a sequential reaction of quinate oxidation to 3-dehydroquinate and its spontaneous conversion to 3-dehydroshikimate under neutral pH. An almost 100% conversion rate from quinate to 3-dehydroshikimate was observed. NADP-Dependent cytoplasmic enzymes from the same organism, shikimate dehydrogenase and D-glucose dehydrogenase, were immobilized together with different carriers as an asymmetric reduction system forming shikimate from 3-dehydroshikimate. Blue Dextran 2000, Blue Dextran-Sepharose-4B, DEAE-Sephadex A-50, DEAE-cellulose, and hydroxyapatite were effective carriers of the two cytoplasmic enzymes, and the 3-dehydroshikimate initially added was converted to shikimate at 100% yield. The two cytoplasmic enzymes showed strong affinity to Blue Dextran 2000 and formed a soluble form of immobilized catalyst having the same catalytic efficiency as that of the free enzymes. This paper may be the first one on successful immobilization of NAD(P)-dependent dehydrogenases.
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  • Tetsuro MATSUNAGA, Aya NAKAHARA, Karim M. MINNATUL, Yuichiro NOIRI, Sh ...
    2010 Volume 74 Issue 12 Pages 2445-2450
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Eikenella corrodens is a periodontopathogenic bacterium that forms biofilm even by itself. In this study, we investigated the inhibitory effects of catechins on E. corrodens biofilm formation. Biofilm formation was inhibited by the addition of 1 mM of the catechins with the pyrogallol-type B-ring and/or the galloyl group. The catechins with the galloyl group were effective at smaller doses than those with only the pyrogallol-type B-ring. An inhibitory effect was observed even when these catechins and gallic acid were added at sub-minimal inhibitory concentration (MIC) or at concentrations that showed no bactericidal effect. These results suggest that some catechins at sub-MIC might inhibit biofilm formation. No inhibitory effect of catechins at sub-MIC on biofilm formation was observed in the luxS deletion mutant. Our studies suggest that some species of catechins with the galloyl group affect autoinducer 2-mediated quorum sensing and thereby inhibit biofilm formation by E. corrodens.
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Microbiology & Fermentation Technology Notes
Microbiology & Fermentation Technology Communications
  • Ken-ichi HASHIMOTO, Koji NAKAMURA, Teruo KURODA, Isamu YABE, Tsuyoshi ...
    2010 Volume 74 Issue 12 Pages 2546-2549
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    The function of the NCgl1221-encoded protein of Corynebacterium glutamicum was analyzed using Bacillus subtilis as host because a method for preparing the giant provacuole required for electrophysiological studies has been established. Expression of NCgl1221 in a strain deficient in mscL and ykuT, both of which encode mechanosensitive channels, resulted in an 8.9-fold higher cell survival rate upon osmotic downshock than the control. Electrophysiological investigation showed that the giant provacuole prepared from this strain, expressing NCgl1221, exhibited significantly higher pressure-dependent conductance than the control. These findings show that the NCgl1221-encoded protein functions as a mechanosensitive channel.
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  • Osao ADACHI, Roque A. HOURS, Yoshihiko AKAKABE, Somboon TANASUPAWAT, P ...
    2010 Volume 74 Issue 12 Pages 2555-2558
    Published: December 23, 2010
    Released: December 23, 2010
    [Advance publication] Released: December 07, 2010
    JOURNALS FREE ACCESS
    Production of 4-keto-D-arabonate (4KAB) was confirmed in a culture medium of Gluconacetobacter liquefaciens strains, newly isolated from water kefir in Argentina. The strains rapidly oxidized D-glucose, D-gluconate (GA), and 2-keto-D-gluconate (2KGA), and accumulated 2,5-diketo-D-gluconate (25DKA) exclusively before reaching the stationary phase. 25DKA was in turn converted to 4KAB, and 4KAB remained stable in the culture medium. The occurrence of 4KAB was assumed by Ameyama and Kondo about 50 years ago in their study on the carbohydrate metabolism of acetic acid bacteria (Bull. Agr. Chem. Soc. Jpn., 22, 271–272, 380–386 (1958)). This is the first report confirming microbial production of 4KAB.
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