Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
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Award Review
  • Yukishige ITO, Yoichi TAKEDA
    2013 Volume 77 Issue 12 Pages 2331-2338
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Protein quality control (QC) in the endoplasmic reticulum (ER) comprises many aspects, including folding and transport of nascent proteins and degradation of misfolded proteins. Recent studies have revealed that high-mannose-type glycans play pivotal roles in the QC process. To gain knowledge of the molecular basis of this process with well-defined homogeneous compounds, we achieved a convergent synthesis of high-mannose-type glycans and their functionalized derivatives. A major part of our study focused on analyses of UDP-Glc: glycoprotein glucosyltransferase (UGGT) and ER glucosidase II, which play crucial roles in glycoprotein QC, to clarify their specificities. In addition, we established an in vitro assay system mimicking the in vivo condition, which is highly crowded due to the presence of various macromolecules.
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Organic Chemistry Regular Paper
  • Tran Manh HUNG, Nguyen Xuan HAI, Nguyen Trung NHAN, Ton That QUANG, Tr ...
    2013 Volume 77 Issue 12 Pages 2378-2382
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Two new phenolic compounds, caesalpiniaphenols G–H (1 and 2), were isolated from Vietnamese Caesalpinia sappan heartwood. The chemical structures were established mainly by extensive spectroscopic studies and chemical evidence. Compounds 1 and 2 showed potent inhibitory activity against HL-60 cancer cell lines with respective IC50 values of 16.7 and 22.5 µg/mL. Treating HL-60 cells with various concentrations of 1 resulted in growth inhibition and the induction of apoptosis.
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Organic Chemistry Note
  • Daxin LI, Kengo SHIGETOMI, Shinya MITSUHASHI, Makoto UBUKATA
    2013 Volume 77 Issue 12 Pages 2499-2501
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Maillard reaction inhibitors could be useful therapeutics for diabetes and other age-related diseases. We isolated for the first time 4-O-demethylsilvaticol (1) and (−)-mitorubrin (2) as Maillard reaction inhibitors from Paecilomyces sp. 3193B. Among the isolated inhibitors, 2 showed most potent inhibitory effect by an SDS–PAGE assay on cross-linked protein formation and by a fluorescent assay on AGE formation.
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Biochemistry & Molecular Biology Regular Papers
  • Haibin WANG, Li SHEN, Xinming LI, Minglei SUN
    2013 Volume 77 Issue 12 Pages 2348-2355
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    1'-Acetoxychavicol acetate (ACA), extracted from rhizomes of tropical ginger, possesses antitumor properties against a wide variety of malignancies. MicroRNAs have been found to act as oncogenes and as tumor suppressor genes in the development of cancer. The purpose of this study was to investigate the miRNA involved in the molecular mechanisms of ACA action on tumor inhibition. It was found that ACA significantly inhibited the growth of human head and neck squamous cell carcinoma cell line HN4 and induced cell apoptosis. Further studies indicated that ACA downregulated the expression of miR-23a in HN4 cells. Transfection with anti-miR-23a inhibited the proliferation of HN4 cells and induced cell apoptosis. In addition, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was confirmed to be the target of miR-23a. Taken together, our findings suggest that ACA might have anticancer effects against human head and neck cancer through downregulation of miR-23a, which can repress tumor suppressor PTEN.
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  • Hui-Seong KIM, Ok-Kyoung KWON, Ji-Won PARK, Hye Gwang JEONG, Sei-Ryang ...
    2013 Volume 77 Issue 12 Pages 2356-2361
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    The biological activity of Mastixia arborea (MA) relates to inflammation, but the underlying mechanisms are largely unknown. We confirmed the anti-inflammatory effects of a methanol extract of MA extract on lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage cells and carrageenan-induced mice paw edema. The MA extract significantly inhibited nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-1β (IL-1β), and IL-6 production in LPS-stimulated RAW264.7 cells. In vitro expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was suppressed by the extract. The extract attenuated acute inflammatory responses in carrageenan-induced mice paw edema. A mechanism study indicated that translocation of the NF-κB (p65) subunit into the nucleus and phosphorylation of ERK and JNK were inhibited by the extract. These results indicate that the extract is an effective suppressor of the inflammatory response, blocking the phosphorylation of ERK and JNK and the translocation of NF-κB in macrophages, thereby producing an anti-inflammatory effect in vivo.
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  • Mary of the Sea GARCÍA-MOLINA, Joseph Luis MUÑOZ-MUÑO ...
    2013 Volume 77 Issue 12 Pages 2383-2388
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Tyrosinase exists in three forms in the catalytic cycle depending on the oxidation state of the copper: met- (Em), oxy- (Eox), and deoxy- (Ed). When O-quinones, products of the enzymatic reaction, evolve chemically to generate an O-diphenol in the reaction medium, the enzyme acts on a monophenol with O-diphenol as reductant, converting Em to Ed. The binding of Ed to molecular oxygen gives Eox, which is active on monophenols, but when the O-quinone product does not generate O-diphenol through chemical evolution, the monophenol does not act as an enzyme substrate. The fact that Eox can be formed from Em with hydrogen peroxide can be used to help identify whether a monophenol is a substrate of tyrosinase. The results obtained in this study confirm that compounds previously described as inhibitors of the enzyme are true substrates of it.
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  • Guofang ZENG, Fang ZHONG, Jin LI, Shaojun LUO, Peihua ZHANG
    2013 Volume 77 Issue 12 Pages 2389-2396
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Hypertrophic scar (HS) is a dermal fibroproliferative disorder characterized by excessive deposition of extracellular matrix. Here, to investigate the regulative effects of resveratrol, a natural antioxidant compound, on fibroblasts from human skin HS tissue, a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the inhibitory effect of resveratrol on cells. Cellcycle progression and apoptosis were measured by flow cytometry and Hoechst 33258 staining respectively. The hydroxyproline content and mRNA expression levels of type I and III procollagen were measured separately by ELISA and reverse transcription-polymerase chain reaction (RT-PCR). The results indicated that resveratrol significantly inhibited cell growth, arresting the cell cycle at the G1 phase and inducing apoptosis in the fibroblasts, decreasing hydroxyproline (or collagen) levels, and downregulating the expression levels of type I and III procollagen mRNA. Taken together, these data indicate that resveratrol-mediated reduction of collagen in fibroblasts is at least partially effected by causing inhibitory cell growth, cellcycle arrest, and apoptosis, and they suggest that resveratrol is a potential agent for HS treatment.
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  • Cheng-Hong HSIEH, Li-Hao CHENG, Hsi-Hsien HSU, Tsung-Jung HO, Chuan-Ch ...
    2013 Volume 77 Issue 12 Pages 2397-2404
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    The IGF-IR/PI3K/Akt signaling pathway inhibited GSK3-β activity by phosphorylation and this promoted β-catenin nuclear localization. Our previous study indicated that β-catenin mRNA level was significantly higher in tumor areas than in non-tumor ones, especially in late pathologic stage tumors. However, β-catenin inhibition resulted in significantly suppressed migration and invasion ability of HA22T cells. Thus, Wnt/β-catenin pathway over-activation might be involved in metastatic enhancement of apicidin-resistant HA22T cell metastasis. Apicidin-resistant (AR) HA22T cells showed higher β-catenin nuclear accumulation and significantly decreased GSK-3-β protein level, in relation to parental cells. Results also indicated that AR cells increased abundantly in Tbx3, a downstream target of Wnt/β-catenin that it is implicated in liver cancer. AR cells also inhibited the MEK/ERK/PEA3 pathway which promoted MMP-2 activation. But, apicidin-resistant effect was totally reversed by LY294002 and AG1024. In conclusion, Apicidin-R HA22T cells activated the Wnt/β-catenin pathway and induced, MMP-2 expression via IGF-IR/PI3K/Akt signaling further enhancing cell the metastatic effects.
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  • Yit-Lai CHOW, Fumihiko SATO
    2013 Volume 77 Issue 12 Pages 2405-2412
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Metabolic syndrome and related disorders are increasingly prevalent in contemporary society, and thus pose the need for potent agents to control lipid accumulation in the body. This study indicates that Caenorhabditis elegans was effective in screening for potent lipid metabolism modulators with berberine as a model compound. Among the various isoquinoline alkaloids tested, sanguinarine, a benzophenanthridine alkaloid, was found to be the most potent. Sanguinarine, like berberine, reduced lipid accumulation through AMP-activated protein kinase activation. Analysis of AMPK (aak-1 and aak-2) RNAi worms revealed that effects were aak-2-dependent. Characterization of worms with knockdown nhr-49, a hormone nuclear receptor gene that functions as a key regulator of fat consumption, showed that both alkaloids were effective even in these markedly lipid-accumulating nhr-49 RNAi worms, suggesting that they predominantly affect lipid synthesis, rather than fatty acid β-oxidation. The versatility of C. elegans for the purpose of lipid-modulating chemical screening and characterization of the underlying mechanisms is discussed.
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  • Naoto YAMAMOTO, Satoshi FUJIWARA, Kana SAITO-IIZUMI, Asuka KAMEI, Fumi ...
    2013 Volume 77 Issue 12 Pages 2413-2418
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Linalool has two enantiomers, (R)-linalool and (S)-linalool. Both are known to possess several biological activities in stressed animals. Our previous work revealed that inhalation of (R)-linalool altered hypothalamic gene expression in rats under stress. In the present study, we monitored hypothalamic gene expression in restrained rats with and without (S)-linalool inhalation by DNA microarray. The entire gene expression profile showed that inhalation of (S)-linalool significantly changed the expression levels of 316 hypothalamic genes in the restrained rats. The differentially expressed genes (e.g., App, Avp, Igf2, Igfbp2, Sst and Syt5) were found to relate to cell-to-cell signaling and nervous system development. These results indicate that (S)-linalool influences hypothalamic gene expression in restrained rats, and that inhalation of (S)-linalool under the stressed condition has some effects on stress-related biological responses.
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  • Ginga SHIMAKAWA, Mayumi SUZUKI, Eriko YAMAMOTO, Akiko NISHI, Ryota SAI ...
    2013 Volume 77 Issue 12 Pages 2441-2448
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    To elucidate the scavenging systems of sugar- and lipid-derived reactive carbonyls (RCs) in the cyanobacterium Synechocystis sp. PCC 6803 (S. 6803), we selected proteins from S. 6803 based on amino-acid (AA) sequence similarities with proteins from Arabidopsis thaliana, and characterized the properties of the GST-fusion proteins expressed. Slr0942 catalyzed the aldo-keto reductase (AKR) reaction scavenging mainly sugar-derived RCs, methylglyoxal (MG). Slr1192 is the medium-chain dehydrogenase/redutase (MDR). It catalyzed the AKR reaction scavenging several lipid-derived RCs, acrolein, propionaldehyde, and crotonaldehyde. Slr0315 is a short-chain dehydrogenase/redutase (SDR), and it catalyzed only the reduction of MG in the AKR reaction. Slr0381 catalyzed the conversion of hemithioacetal to S-lactoylglutahione (SLG) in the glyoxalase (GLX) 1 reaction. Sll1019 catalyzed the conversion of SLG to glutathione and lactate in the GLX2 reaction. GLX1 and GLX2 compose the glyoxalase system, which scavenges MG. These enzymes contribute to scavenging sugar- and lipid-derived RCs as scavenging systems.
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  • Takafumi YAMASHINO, Miki KITAYAMA, Takeshi MIZUNO
    2013 Volume 77 Issue 12 Pages 2454-2460
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Plant elongation growth on a day-to-day basis is enhanced under specific photoperiod and temperature conditions. Circadian clock is involved in the temperature adaptive photoperiodic control of plant architecture, including hypocotyl elongation in Arabidopsis thaliana. In this regulation, phytochrome interacting transcriptional factors, PIF4 and PIF5, are activated at the end of night under short photoperiod or high temperature conditions, due to the coincidence between internal (circadian rhythm of the transcripts) and external (length of dark period) time cues. It is previously found that biosynthesis or metabolism of phytohormones including auxin, and their signal transduction-related genes are downstream targets of circadian clock and PIF4/PIF5 mediated external coincidence mechanism. Brassinosteroid and gibberellic acid played a positive role in the hypocotyl elongation of seedlings under light and dark cycle conditions. On the other hand, cytokinin and jasmonic acid played an opposite role. In this study, diurnal expresson profile of a gene encoding a sulfotransferase family protein that is involved in the jasmonic acid metabolism, ST2A, was examined. It was found that transcription of ST2A is induced at the end of night under LD/22 °C and SD/28 °C conditions according to the external coincidence mechanism. The results of this study support the idea that the circadian clock orchestrates a variety of hormone-signaling pathways to regulate the photoperiod and temperature-dependent morphogenesis in A. thaliana.
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  • Kazuya TOMIMOTO, Yasuko FUJITA, Tomoko IWAKI, Yasunori CHIBA, Yoshifum ...
    2013 Volume 77 Issue 12 Pages 2461-2466
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Saccharomyces cerevisiae strains engineered previously to produce proteins with mammalian high mannose structures showed severe growth defects and decreased protein productivity. In strain YAB101, derived from one of these strains by a mutagenesis technique based on the disparity theory of evolution, these undesirable phenotypes were alleviated. Here we describe further engineering of YAB101 with the aim of synthesizing heterologous glycoproteins with Man5GlcNAc2, an intermediate for the mammalian hybrid and complex type oligosaccharides. About 60% conversion of Man8GlcNAc2 to Man5GlcNAc2 was observed after integration of Aspergillus saitoi α-1,2-mannosidase fused to the transmembrane domain of S. cerevisiae Och1. To obtain a higher yield of the target protein, a protease-deficient version of this strain was generated by disruption of PEP4 and PRB1, resulting in YAB101-4. Inactivation of these vacuolar proteases enhanced the secretion of human interferon-β by approximately 10-fold.
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  • Masaki J. FUJITA, Ryuichi SAKAI
    2013 Volume 77 Issue 12 Pages 2467-2472
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Desferrioxamines E (1), D2 (2), X1 (3), and X2 (4), four macrocyclic N-hydroxy-N-succinyl diamine-based siderophores, were produced efficiently by heterologous expression of a fusion biosynthetic gene cluster. This expression system consisted of three genes (mbsA-C) from marine metagenomic DNA and one gene (dfoCC) from the terrestrial bacterium Erwinia amylovora. The first three genes are functional in the production of the common monomers N-hydroxy-N-succinyl cadaverine (5, HSC) and N-hydroxy-N-succinyl putrescine (6, HSP), whereas dfoCC catalyzes the oligomerization and the macrocyclization reactions of compounds 5 and 6 to form compounds 14. This fusion gene cluster system provides a convenient expression platform for various biosynthetic genes of HSC-HSP based siderophores by simply switching the fourth gene by the cassette process.
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  • Kazutaka ITO, Kohshin HAMASAKI, Aya KAYAMORI, Phuong Anh Thi NGUYEN, K ...
    2013 Volume 77 Issue 12 Pages 2473-2479
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Escherichia coli RNase G is involved in the degradation of several mRNAs, including adhE and eno, which encode alcohol dehydrogenase and enolase respectively. Previous research indicates that the 5' untranslated region (5'-UTR) of adhE mRNA gives RNase G-dependency to lacZ mRNA when tagged at the 5'-end, but it has not been elucidated yet how RNase G recognizes adhE mRNA. Primer extension analysis revealed that RNase G cleaved a phosphodiester bond between −19A and −18C in the 5'-UTR (the A of the start codon was defined as +1). Site-directed mutagenesis indicated that RNase G did not recognize the nucleotides at −19 and −18. Random deletion analysis indicated that the sequence from −145 to −125 was required for RNase G-dependent degradation. Secondary structure prediction and further site-directed deletion suggested that the stem-loop structure, with a bubble in the stem, is required for RNaseG-dependent degradation of adhE mRNA.
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Biochemistry & Molecular Biology Notes
Food & Nutrition Science Regular Papers
  • Tatsuya MORIYAMA, Erika YANO, Kazumi KITTA, Shin-ichi KAWAMOTO, Yukio ...
    2013 Volume 77 Issue 12 Pages 2371-2377
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    The levels of food allergens in gamma-irradiated soybean (0, 2.5, 5, 7.5, 10, 20, and 30 kGy) were investigated by immunoblotting and ELISA, using allergen-specific antibodies and patient serum. After 3 months of storage, Coomassie brilliant blue (CBB) staining indicated similar total protein profiles among the treatments, but that some proteins were degraded by irradiation at high doses. Immunoblotting with specific antibodies for major soybean allergens (β-conglycinin, Gly m Bd 30 K, soybean trypsin inhibitor, and Gly m 4) resulted in apparent band profiles and intensities that were not significantly changed by irradiation. Competitive inhibition ELISA analyses suggested that there were no significant changes in the allergen contents, except for a decrease in the soybean trypsin inhibitor. The patient IgE binding allergenic protein patterns were not changed by irradiation up to 30 kGy. ELISA using patient serum also revealed that the IgE reactivity to the irradiated soybean extract did not increase from the level of the control, but that the reactivity to some patient serum IgE was significantly decreased by irradiation.
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  • Sumiko NAKAMURA, Yohei NAKANO, Hikaru SATOH, Ken'ichi OHTSUBO
    2013 Volume 77 Issue 12 Pages 2419-2429
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Cooked grains of ae rice cultivars are too hard and non-sticky due to the presence of long-chain amylopectin, and ae rice cultivars are therefore called ``super-hard rice'' and cannot be used as table rice. However, they are promising in terms of their bio-functionality such as preventing diabetes. Miso (soybean paste) is a yeast-fermented food, made from steamed soybeans, salt, and inoculated cereals known as koji, made from rice, barley, or soybeans.
    We investigated the effects of soaking ae mutant rice cultivars in a miso suspension. Their chemical components, physical properties, and enzyme activities were measured under different conditions (milled rice before or after soaking in a 5% barley-koji miso suspension). Rice grains cooked after soaking in the miso suspension were less hard and more sticky than those cooked after soaking in water. Rice grains cooked after soaking in a 5% barley-koji miso suspension maintained high amounts of resistant starch and dietary fiber, and were fortified with polyphenols and isoflavones. Palatable and bio-functional ae rice could therefore be produced by cooking after soaking in a 5% barley-koji miso suspension.
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  • Nobuyasu MATSUURA, Kanae GAMO, Hiroyuki MIYACHI, Munekazu IINUMA, Teru ...
    2013 Volume 77 Issue 12 Pages 2430-2435
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    We tested the peroxisome proliferator-activated receptor (PPAR)δ agonistic activity of a Garcinia mangostana pericarp extract to develop a treatment for the metabolic syndrome, and demonstrated γ-mangostin to be an active compound on the basis of a luciferase reporter gene assay. γ-Mangostin induced the expression of the uncoupling protein-3 (UCP-3) gene which is related to energy expenditure and fat metabolism in L6 cells. We showed that γ-mangostin is a dual agonist that activates both PPARδ and PPARα. γ-Mangostin also induced the expression of acyl-CoA synthase and carnitine palmitoyl-transferase 1A genes in HepG2 cells. These results suggest the potential of γ-mangostin as a preventive agent of the metabolic syndrome.
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Microbiology & Fermentation Technology Regular Papers
  • Chifumi KITAZAKI, Setsuko NUMANO, Akira TAKANEZAWA, Tomoyasu NISHIZAWA ...
    2013 Volume 77 Issue 12 Pages 2339-2347
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    The cyanobacterium semi-filamentous multicellular strain ABRG5-3 undergoes cell lysis as a unique feature that occurs due to growth condition changes from normal cultivation with shaking to static cultivation without shaking in liquid culture (Nishizawa et al., 2010). Microscopic observation and energy dispersive X-ray spectrometer (EDX) analysis have revealed that lysis is involved in the accumulation of polyphosphate compounds and the disintegration of thylakoid membranes in cells. Static cultivation, dark or red light exposure, and temperature (22 to 42 °C) conditions were found to be effective factors for the induction of lysis. Moreover, stress induced by salts, osmotic pressure with sucrose, and the depletion of nitrogen or phosphate in cultures also induced ABRG5-3 cell lysis. Based on these results, we discuss lysis and its utilization in the biotechnology industry.
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  • Jamroonsri POOMTIEN, Jiraporn THANIYAVARN, Pairoh PINPHANICHAKARN, Sas ...
    2013 Volume 77 Issue 12 Pages 2362-2370
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Cyberlindnera samutprakarnensis JP52T, isolated from cosmetic industrial wastes in Thailand, was found to be an efficient biosurfactant-producing yeast when cultured in a medium containing (2% (w/v) glucose and 2% (v/v) palm oil at 30 °C, 200 rpm for 7 d. The crude biosurfactant had the ability to reduce the surface tension from 55.7 to 30.9 mN/m at 25 °C with a critical micelle concentration (CMC) of 0.046%. Physicochemical analysis of the crude biosurfactant revealed that it had wide ranges of optimum pH and pH stability at 6–9 and 3–10 respectively. It was also thermostable and retained 80% activity even after heat treatment, and it tolerated NaCl at 1.0–10%. Furthermore, it effectively emulsified various vegetable oils with an E24 value of over 80%. A partially purified biosurfactant fraction was analyzed for its structure by MALDI-TOF MS and NMR. This revealed that the biosurfactant mainly contained sophorolipids in C18-(MW 574) and C16-diaceltylated (MW 662) forms.
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  • Seiji OCHIAI, Tomohiro MOROHOSHI, Ayane KURABEISHI, Masahiro SHINOZAKI ...
    2013 Volume 77 Issue 12 Pages 2436-2440
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    N-Acylhomoserine lactones (AHLs) function as quorum-sensing signaling molecules in many Gram-negative bacteria. We isolated a total of 672 bacterial strains from activated sludge obtained from seven sewage treatment plants in Tochigi Prefecture, Japan, and screened for AHL-producing and degrading strains. Isolates (n=107) stimulated AHL-mediated purple pigment production in AHL reporter strains Chromobacterium violaceum CV026 and VIR07. Based on their 16S rRNA gene sequences, most of these AHL-producing isolates were assigned to the genus Aeromonas, and they were divided into six groups. Isolates (n=46) degraded N-decanoyl-L-homoserine lactone (C10-HSL) within 24 h. Based on their 16S rRNA gene sequences, the most dominant AHL-degrading isolates were assigned to the genus Acinetobacter and divided into six groups. Strains Ooi24, Omo91, and Uzu81, which showed higher C10-HSL-degrading activity, showed putative AHL-acylase activity.
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  • Sang Youn HWANG, Kazunori NAKASHIMA, Naoko OKAI, Fumiyoshi OKAZAKI, Mi ...
    2013 Volume 77 Issue 12 Pages 2449-2453
    Published: December 23, 2013
    Released: December 23, 2013
    [Advance publication] Released: December 07, 2013
    JOURNALS FREE ACCESS
    Amylases from Streptomyces are useful in the production of maltooligosaccharides, but they have weak thermal stability at temperatures higher than 40 °C. In this study, α-amylase (SAV5981 gene of Streptomyces avermitilis) was expressed from Streptomyces lividans 1326 and purified by ammonium sulfate fractionation followed by anionic chromatography (Q-HP sepharose). The properties of the purified SAV5981 amylase were determined by the starch-iodine method. The effect of metal ions on amylase activity was investigated. The optimal temperature shifted from 25 to 50 °C with the addition of the Ca2+ ion. The thermal stability of SAV5981 was also dramatically enhanced by the addition of 10 mM CaCl2. Improvement of the thermal stability of SAV5981 was examined by CD spectra in the presence and the absence of the Ca2+ ion. Thin-layer chromatography (TLC) analysis and HPLC analysis of starch degradation revealed that SAV5981 mainly produced maltose and maltotriose, not glucose. The maltoorigosaccharide-producing amylase examined in this study has the potential in the industrial application of oligosaccharide production.
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