Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 63 , Issue 8
Showing 1-36 articles out of 36 articles from the selected issue
Review
  • Michiko KATO, Rikimaru HAYASHI
    1999 Volume 63 Issue 8 Pages 1321-1328
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      This review covers high pressure effects on lipids, lipid bilayers, and biochemical observations recently found in the field of high-pressure bioscience and biotechnology including deep-sea microbiology and food science. To explain these phenomena in a unified model, recent studies of physical and chemical properties of artificial membranes and natural membranes are summarized. On the basis of this newly described knowledge, high pressure effects on biochemical events are considered at the molecular level and concluded that high pressure induces decreases in biomembrane fluidity and phase transitions that result in breakage of the membrane, and finally, leads to the destruction of bilayer membrane accompanied by denaturation of membrane-associated proteins.
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Analytical Chemistry Regular Paper
  • Shoichi YASUNO, Kazuko KOKUBO, Masugu KAMEI
    1999 Volume 63 Issue 8 Pages 1353-1359
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      A new method is reported that can be performed within a single vessel to analyze the composition of aldose, hexosamine, and sialic acid residues of glycoproteins, glycolipids, and oligosaccharides. Glycoconjugates are treated with sialidase or subjected to mild acid hydrolysis, before being treated with N-acetylneuraminic acid aldolase to convert the free sialic acid residues to their corresponding N-acylmannosamines. The reaction mixture is then successively subjected to acid hydrolysis (in order to produce monosaccharides), N-acetylation, and conversion with ρ-aminobenzoic acid ethyl ester (ABEE). The ABEE-converted monosaccharides are simultaneously determined by reverse-phase high-performance liquid chromatography. Determination of the sugar compositions of bovine fetuin, II3NeuGcα-LacCer, and 3′-sialyllactose with this method was found to be highly accurate. Linearity of the peak area vs. the amount of bovine fetuin ranged from 1 to 50 μg in all ABEE-converted monosaccharides. With a slight modification to this method, sialic acid residues can be separately determined as NeuAc and NeuGc. This novel method and its modified version are used to demonstrate the sugar compositions of α1-acid glycoproteins from several sources.
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Analytical Chemistry Notes
  • Hiroaki FUTATSUYAMA, Toshifumi YUI, Kozo OGAWA
    1999 Volume 63 Issue 8 Pages 1481-1483
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      A simple method to obtain the molecular weight of curdlan was found by viscometry in its alkaline or DMSO solution. DMSO was found to be the most appropriate solvent for measuring Mv of curdlan. Based on two Sakurada-Houvink equations, [η]=KMa, which have been obtained so far in alkaline solutions, two sets of parameters of the equation in the DMSO solution, that is, K=3.5×10-4, a=0.65 and K=1.6×10-4, a=0.74 were introduced, respectively. Both parameter sets seemed to serve practically to measure the molecular weight of curdlan. In addition, using the equation obtained with several NaOH concentrations, the previous speculation that curdlan conformation changes from a rigid rod to random coil with alkaline concentration was confirmed.
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  • Shuzo YAMAGATA, Tomonori IWAMA
    1999 Volume 63 Issue 8 Pages 1503-1505
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      A procedure is described to precisely determine a very small amount of cystine in the presence of a large amount of cysteine. After completely modifying cysteine with N-ethylmaleimide, the remaining reagent was reacted with DL-homocysteine. Cystine was determined, after being reduced with dithiothreitol, by the reaction with ninhydrin carried out under acidic conditions. The procedure makes it possible to precisely determine the amount of cystine present with cysteine in a concentration ratio of 1:2,000. By employing this procedure, auto-oxidation of cysteine to cystine in a mixture for the L-cysteine α,β-elimination reaction was investigated.
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  • Kazuaki AKASAKA, Hirotaka OHTA, Yoshimi HANADA, Hiroshi OHRUI
    1999 Volume 63 Issue 8 Pages 1506-1508
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Two HPLC-post column systems, a conventional-size system and a semi-micro system, for the simultaneous determination of lipid hydroperoxides were developed. The hydroperoxides of free fatty acids, phosphatidylcholines, triacylglycerols and cholesterol esters were individually determined at the pmol level with good reproducibility by using gradient elution and post-column detection with diphenyl-1-pyrenylphosphine.
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Organic Chemistry Regular Papers
Organic Chemistry Notes
Biochemistry & Molecular Biology Regular Papers
  • Rei ABE, Kensuke YOSHIDA, Masanobu AOYAGI, Shin KASAHARA, Eiji ICHISHI ...
    1999 Volume 63 Issue 8 Pages 1329-1335
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Cultured cells of rice (Oryza sativa cv Sasanishiki) produce two α-amylase isozymes, AMY-I and AMY-III. Using a bacterial expression system, eight chimeric genes constructed with various combination of AMY-I and AMY-III cDNA fragments were expressed, and each recombinant chimeric protein was characterized. Four of the eight recombinant enzymes having region c (one of the four regions having unconserved base sequences between AMY-I and AMY-III cDNAs) of AMY-I showed the same enzyme characteristics as that of native AMY-I, which had high temperature optimum at 50°C. The other four chimeric proteins carrying region c of AMY-III showed the AMY-III type characteristics, which were a low temperature optimum at 25°C and susceptibility to a higher maltooligosaccharide (G17) substrate. The unconserved region c is involved in the decision of the characteristic of AMY-I or AMY-III.
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  • Kengo USUI, Keiji IBATA, Tohru SUZUKI, Keiichi KAWAI
    1999 Volume 63 Issue 8 Pages 1346-1352
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      A gene, xynX, encoding a novel xylanase, was cloned from Aeromonas caviae ME-1. This gene encoded an enzyme that was constituted of 334 amino acid residues (38,580 Da) and was similar in sequence to Family 10 (Family F) β-1,4 endo-xylanases. XynX produced only xylobiose and xylotetraose from birch wood xylan, and xylotriose, xylopentaose, and higher oligosaccharides were not detected in the TLC analysis. We designated it as X2/X4-forming xylanase. This enzyme does not have transglycosylation activity. These data suggested that this enzyme is a possible exo-xylanase. According to homology modeling, the enzyme has a ring-shaped (α/β)8 barrel (TIM barrel) structure, typical of Family 10 endo-xylanases, with the extraordinary feature of a longer bottom-loop structure.
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  • Anh Hoa NGUYEN, Toshio TOMITA, Morihiko HIROTA, Tsuruji SATO, Yoshiyuk ...
    1999 Volume 63 Issue 8 Pages 1360-1369
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Carotovoricin Er has been isolated as a phage-tail-like bacteriocin from the plant pathogen Erwinia carotovora Er [Kamimiya, S. et al., (1977), Agric. Biol. Chem. 41, 911-912]. However, the fine morphology and structural composition of carotovoricin Er remained to be studied because a large amount of contracted carotovoricin Er were present in the bacteriocin preparations so far obtained. To obtain intact carotovoricin Er and its major parts, we developed simple and efficient purification methods including the use of sucrose density gradient centrifugation in the presence of 10-20% (v/v) ethanol. Electron microscopy for the purified carotovoricin Er showed the presence of a novel antenna-like structure at the proximal end of the phage-tail-like particle, which consisted of a sheath-and-core part, a baseplate, and tail fibers. Contracted sheath and inner core were purified as hollow cylindrical structures with longitudinal lengths of 69 and 174 nm, respectively, and tail fibers were purified as a fibrous structure with length of 63 nm. SDS-polyacrylamide gel electrophoresis showed the presence of single major proteins of 50, 20, and 68 kDa in the isolated sheath, core, and tail fiber, respectively. Three other minor proteins of 46, 44, and 35 kDa were also identified as the structural proteins of carotovoricin Er, which may be the candidate proteins for the antenna-like and the base plate structures. Thus carotovoricin Er consists of at least 6 protein components.
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  • Dong-Sun LEE, Sang-Han LEE, Gi-Seok KWON, Hong-Kum LEE, Joo-Hyung WOO, ...
    1999 Volume 63 Issue 8 Pages 1370-1373
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Dihydrotanshinone I induced topoisomerase I-mediated DNA cleavage in vitro as strongly as camptothecin, but topoisomerase II-mediated DNA cleavage was not affected. In a DNA relaxation assay using calf thymus DNA topoisomerase I and supercoiled pBR322 plasmid DNA, dihydrotanshinone I reduced topoisomerase I-mediated DNA relaxation in a dose-dependent manner. Heat treatment (65°C) of the reaction mixture containing dihydrotanshinone I and topoisomerase I resulted in a substantial reduction in DNA cleavage, suggesting topoisomerase I and dihydrotanshinone I may form a reversible cleavable complex to induce DNA damage. A DNA unwinding assay using T4 DNA ligase showed that dihydrotanshinone I is a very weak DNA intercalator. These results suggest that dihydrotanshinone I inhibits the catalytic activity of topoisomerase I by the formation of a cleavable complex and at least in part through the intercalation into DNA.
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  • Osamu NAKAMURA, Jamil Ahsan KAZI, Tomokazu OHNISHI, Naokatu ARAKAKI, Q ...
    1999 Volume 63 Issue 8 Pages 1383-1391
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Rat fetuin, which is the rat counterpart of human α2-HS glycoprotein and bovine fetuin, is only detectable in calcified tissues such as bone matrices and dentin, and bone cells such as osteoblasts and osteocytes immunohistochemically. The effect of this protein on bone resorption was examined to study its physiological role in bone metabolism. Rat fetuin increased bone resorption in the presence of low concentrations of parathyroid hormone (PTH), but it had no activity on bone resorption without PTH. The increase in bone resorption by PTH and PTH plus rat fetuin was inhibited by the addition of chymostatin, an inhibitor for cathepsin L. Moreover, we found that when type I collagen from rat was preincubated with rat fetuin, the digestion of rat type I collagen by cathepsin L was increased. These findings suggest that rat fetuin present in bone matrix is important in bone resorption.
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  • Takashi KAMAKURA, Jin-zhong XIAO, Woo-Bong CHOI, Takamasa KOCHI, Syuic ...
    1999 Volume 63 Issue 8 Pages 1407-1413
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The conidial germ tube of the fungus Magnaporthe grisea differentiates an infection-specific structure, an appressorium, for penetration into the host plant. Formation of the appressorium is also observed on synthetic solid substrata such as polycarbonate. We found that a plant lectin, concanavalin A, specifically suppressed the appressorium formation without affecting the germling adhesion if it was applied within 2-3 hours after germination. Standing on the result, we constructed a cDNA library that represents the early stage of germ tube development and/or appressorium formation from the 2.5-hour-old germ tubes using a cDNA subtraction strategy by the combination of the biotin labeled driver method and adapter-primed PCR method. Out of 686 colonies of the library, 158 distinct clones’ nucleotide sequences were partially analyzed. Some clones’ expression patterns were detected by RT-PCR and from those results, our library seemed to well represent the objective developmental stage of M. grisea.
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  • Yoichiro SHIBA, Chiho ONO, Kimihisa ICHIKAWA, Nobufusa SERIZAWA, Hiroj ...
    1999 Volume 63 Issue 8 Pages 1414-1419
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The production level of CPY in Saccharomyces cerevisiae KS58-2D/pCY303 was drastically decreased when thiamine was not added to the culture medium. We isolated and characterized the mutants that could produce CPY even though thiamine was absent from the medium. Using complementation screening in the mutants obtained, we isolated a gene that was involved in the thiamine-inducible expression, TIE1, which corresponded to the YDR325w ORF on chromosome IV. The predicted protein sequence of TIE1 did not have significant homology to proteins from public databases. The disruption of the TIE1 gene caused two phenotypes, increase of expression level in thiamine-free medium and ethanol sensitivity. This increase in thiamine-free medium was also observed in the expression under the control of ENO1 or ADH1 promoter in addition to the GAL10 promoter, suggesting that the TIE1 protein is associated with a similar kind of transcriptional mechanism regulated by thiamine.
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  • Nikolai Kirilov CHRISTOV, Hiromasa IMAISHI, Hideo OHKAWA
    1999 Volume 63 Issue 8 Pages 1433-1444
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The DNA sequence of a truncated cry1C gene encoding the active fragment of Bacillus thuringiensis (Bt) δ-endotoxin was fully reconstructed by introduction of silent mutations. Each of the truncated wild type and the synthetic genes encoding the active fragment of the protoxin was introduced into haploid tobacco plants under the control of the rbcS promoter. To facilitate selection of transgenic tobacco plants with high insecticidal activity, a fusion gene encoding both rat CYP1A1 cytochrome P450 and yeast NADPH-P450 oxidoreductase was cotransformed with the wild type cry1C gene. The synthetic gene elevated the levels of Cry1C protein and the mRNA in transgenic tobacco plants as well as mortality in Spodoptera litura larvae. The Cry1C protein was accumulated mainly in the leaf tissues of the transgenic tobacco plants. The results reported here imply that the green-tissue-specific expression of the synthetic cry1C gene is useful for the control of S. litura which was rather resistant to the other types of Bt toxins.
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Biochemistry & Molecular Biology Notes
  • Wakako TSUZUKI, Yoshiaki KITAMURA, Tateo SUZUKI, Tamio MASE
    1999 Volume 63 Issue 8 Pages 1467-1470
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      To establish the utility of lipase as a biocatalyst, the effects of glucose on the hydrolysis activities of lipase were investigated. Among 13 kinds of lipase from microorganisms, 6 lipases were inhibited in hydrolysis up to 50% of the original activities by 10 mM glucose. The activities of other microbial lipases and 2 kind of porcine pancreatic lipases were not affected by the addition of glucose. Six lipases that were sensitive to glucose were modified by a synthetic detergent. After they were converted to modified lipases, they were not inhibited by glucose. Even at 20 mM glucose, each modified lipase retained more than 95% activity compared with that in the absence of glucose. In the modified lipase, the detergent attached to the lipase molecule would disturb the access of glucose to the enzyme. To detect the interaction between lipase and glucose, the fluorescence of tryptophan was traced. The fluorescence intensities of lipases that were inhibited by glucose depended on the concentration of glucose, suggesting that glucose induced some structural change in the lipase molecule.
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  • Hiroo YONEZAWA, Tetsuya UCHIKOBA, Kazunari ARIMA, Makoto KANEDA
    1999 Volume 63 Issue 8 Pages 1471-1474
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Fluorogenic substrates for cathepsin D; A-Tyr-Phe(NO2)-Leu-Leu (A; Ala-Arg-Pro-Lys-Pro-Leu-Leu-, Arg-Pro-Lys-Pro-Leu-Leu-, Pro-Lys-Pro-Leu-Leu-, Lys-Pro-Leu-Leu-, Pro-Leu-Leu-) and B-Phe(NO2)-Tyr-Leu-Leu (B; Arg-Pro-Lys-Pro-Leu-Leu-, Pro-Lys-Pro-Leu-Leu-, Lys-Pro-Leu-Leu-, Pro-Leu-Leu-) (Phe(NO2), p-nitrophenylalanine) were synthesized and digested by cathepsin D and pepsin. The fluorescence at 303 nm (excitation at 260 nm) was increased with the hydrolysis of the substrates. The minimum detectable cathepsin D concentrations for these substrates were 0.5-4 nM and pepsin concentrations were 0.1-0.8 nM except Pro-Leu-Leu-Tyr-Phe(NO2)-Leu-Leu under the following conditions: substrate concentration, 20 μM; measuring time, 3 min. The hydrolysis rate constants (kcat/Km) of B-Phe(NO2)-Tyr-Leu-Leu for cathepsin D were same or 2-3 times greater than A-Tyr-Phe(NO2)-Leu-Leu. On the other hand, those of B-Phe(NO2)-Tyr-Leu-Leu for pepsin were the same or 4-20 times greater than A-Tyr-Phe(NO2)-Leu-Leu. The hydrolysis rates of the substrates by both enzymes tend to increase with the increase of the peptide chain length. The best substrate for cathepsin D was Arg-Pro-Lys-Pro-Leu-Leu-Phe(NO2)-Tyr-Leu-Leu and its kcat/Km was 1.3 μM-1 s-1.
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  • Yuji KANEKO, Hideki SHOJO, Masao YUDA, Yasuo CHINZEI
    1999 Volume 63 Issue 8 Pages 1488-1490
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Nitrophorin-2, isolated from the salivary gland of the blood-sucking insect Rhodnius prolixus, is a nitric oxide (NO) binding protein. We investigated the effects of recombinant nitrophorin-2 NO complex on vascular smooth muscle. The course of relaxation was relative to released NO from recombinant nitrophorin-2 NO complex. Our data suggested nitrophorin-2 was tightly adhesive to the membranes to transport NO into the cell during the insect sting.
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  • Tetsuro YAMASHITA, Emiko KIYOKI, Yasuhiro TOMITA, Hideharu TAIRA
    1999 Volume 63 Issue 8 Pages 1491-1493
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      We have developed a method for the immunoaffinity purification of calnexin, an endoplasmic reticulum molecular chaperone, and analyzed the molecular weight of purified calnexin using matrix-assisted laser adsorption ionization time of flight mass spectrometry (MALDI TOF-MS). Calnexin was thereby found to have a molecular weight of 66.1×103, which is nearly identical to the molecular weight estimated from the protein sequence.
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Food & Nutrition Science Regular Papers
  • Hidefumi YOSHII, Takeshi FURUTA, Takatoki ITOH, Yoshihisa MISAWA, Nori ...
    1999 Volume 63 Issue 8 Pages 1336-1339
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      On the basis of an autocatalytic and a first order reaction kinetics, a nonisothermal oxidation reaction model was developed for n-3 polyunsaturated fatty acid (PUFA) under temperature-programmed linear heating conditions. With this model, the activation energy of oxidative reaction can easily be obtained with at least three linear heating conditions. The temperature-programmed oxidation experiments of ethyl eicosapentaenoate and ethyl docosahexaenoate were done under linear heating conditions of 4 to 12 K/h. The activation energies and the frequency factors obtained were in good agreement with those by the isothermal oxidation experiments reported previously.
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  • Taro TAKAHASHI, Hirokazu MAEDA, Toshiaki AOYAMA, Takashi YAMAMOTO, Kiy ...
    1999 Volume 63 Issue 8 Pages 1340-1345
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      Four-week-old rats were fed on diets containing either no dietary fiber (DF) or a DF source (WSSF, ISF or cellulose) for 4 weeks. The DF level was adjusted to 5%. The WSSF diet contained 3% and 2%, respectively, of WSSF and cellulose. No rat in any group experienced diarrhea, and none of the experimental diets suppressed the growth of rats, the apparent absorption of major nutrients being almost 100%. However, the rate of degradation of DF during the digestive process was significantly different (p<0.05, cellulose, 23.6%; WSSF with cellulose, 64.5% (WSSF degradation only was 91.8%); and ISF, 77.6%). The plasma and liver lipid levels were within normal ranges, although the liver cholesterol level in those rats fed on WSSF and ISF was significantly lower (p<0.05) than in those fed on cellulose. The cecal organic acid contents were in the order of WSSF>ISF>cellulose>DF-free. Furthermore, WSSF was effective in shortening the gastrointestinal transit time. The results indicate that WSSF seems to have favorable effects on the intestinal functions.
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  • Yasuhiro ARII, Nobuyuki TAKAHASHI, Eizo TATSUMI, Masaaki HIROSE
    1999 Volume 63 Issue 8 Pages 1392-1399
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The recombinant ovalbumin produced in Escherichia coli was purified from the cytoplasmic fraction and analyzed for its chemical and conformational properties. The recombinant ovalbumin displayed almost exactly the same circular dichroism and intrinsic tryptophan fluorescence spectra as egg white ovalbumin. As in the egg white protein, four cysteine sulfhydryls and one cystine disulfide were contained in the recombinant protein, according to the results of amino acid analyses; the disulfide bond was found by a peptide mapping analysis to correspond to the native cystine, Cys73-Cys120. According to a gel electrophoresis analysis, the presence of the disulfide bond was accounted for by specific oxidation of the corresponding cysteine residues during purification of the cytoplasmic protein. Unlike the identity in the conformational and peptide structures, none of the post-translational modifications (N-terminal acetylation, phosphorylation, and glycosylation) that are known with egg white ovalbumin were detected in the recombinant protein. The recombinant ovalbumin was transformed into a thermostabilized form in a similar manner to the transformation of egg white protein into S-ovalbumin; alkaline treatment increased the temperature for thermostability by 8.7°C. These data strongly suggest that the post-translational modifications of ovalbumin are not related to the formation mechanism for S-ovalbumin.
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  • Sha FEI, Minoru YAMANOUE, Takahide OKAYAMA
    1999 Volume 63 Issue 8 Pages 1425-1432
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The binding of paratropomyosin to β-connectin, which has been suggested to interact at the A-I junction of a sarcomere, was confirmed by measuring the changes in turbidity of a mixture with changing NaCl concentration, pH and free calcium ions, and by morphological observation and a coprecipitation assay of the aggregates formed in the mixture. Paratropomyosin also bound to the 400-kDa fragment which is the N-terminal portion of β-connectin and contains the A-I junction region. Moreover, the interaction of paratropomyosin with the 400-kDa fragment was enhanced by a calcium ion concentration from 10-7 M to 10-5 M and markedly suppressed above 10-4 M calcium ions. We conclude that paratropomyosin probably binds to the 400-kDa fragment of β-connectin in the A-I junction region in living and pre-rigor skeletal muscle. In postmortem skeletal muscle paratropomyosin may be released from the 400-kDa portion of the connectin filament by increased calcium ion concentration and translocated on to thin filaments to induce meat tenderization.
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Food & Nutrition Science Preliminary Communication
  • Fumitaka HAYASE, Yota TAKAHASHI, Shigeru TOMINAGA, Masayo MIURA, Toshi ...
    1999 Volume 63 Issue 8 Pages 1512-1514
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      D-Xylose (1 M), glycine (0.1 M), and sodium hydrogencarbonate (0.1 M) were dissolved in aqueous 60% ethanol at pH 8.1 and left at 26.5°C for 2 days in a dark room under nitrogen displacement. Blue pigment was isolated and purified from the blue solution by anionic exchange and gel filtration chromatographies. Blue pigment which was designated Blue-M1 (blue Maillard reaction intermediate-1) was identified as 5-{[1,4-(dicarboxymethyl)-5-(2,3-dihydroxypropyl)-2-pyrrolo[3,2-b]pyrrolyl]methine}-1,4-(dicarboxymethyl)-2-(1,2,3-trihydroxypropyl)-pyrrolo[3,2-b]pyrroly-lium. Blue-M1 is supposed to be a dimer of yellow colored pyrrolopyrrole-2-carboxaldehyde compounds. Blue-M1 that reacts readily to yellow compounds has a polymerizing activity, suggesting it is an important Maillard reaction intermediate through the formation of melanoidins.
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Microbiology & Fermentation Technology Regular Papers
  • Masaaki TAZOE, Keiko ICHIKAWA, Tatsuo HOSHINO
    1999 Volume 63 Issue 8 Pages 1378-1382
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The production of vitamin B6 was studied in about 1,590 bacterial isolates from soil, and an isolate, 28-21, identified as Rhizobium leguminosarum was obtained as a vitamin B6 high producer. Then, the production of vitamin B6 by commercially available Rhizobium strains was examined, and many of the tested strains excreted large amounts of vitamin B6 into the culture broth. The best producer of vitamin B6 was R. meliloti IFO 14782, which produced 51 mg per liter. Media study for the vitamin B6 production was done with R. meliloti IFO 14782; the strain was able to excrete 84 mg of vitamin B6 per liter, 79 mg per liter of which was pyridoxol.
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  • Kasumi NOGUCHI, Norihiko TSUKAGOSHI, Rikizo AONO
    1999 Volume 63 Issue 8 Pages 1400-1406
    Published: 1999
    Released: March 11, 2005
    JOURNALS FREE ACCESS
      The growth curve (increase in the number of viable cells) of a toluene-tolerant strain Pseudomonas putida Px51T was not reproducible in the presence of harmful organic solvents, such as p-xylene and toluene. The survival often fluctuated the during late exponential phase of growth. The repetitive growth was obtained by maintaining pO2 20-40% (v/v) in the culture flask. However, even under these aerobic conditions, the cells starved for a carbon source were killed by exposure to harmful solvents. The tolerance to organic solvents was lowered greatly by treatment with a proton conductor, carbonyl cyanide m-chlorophenylhydrazone (CCCP), or an electron transport chain inhibitor, sodium azide. Px51T treated with CCCP lost tolerance to a wide variety of organic solvents with log Pow of 2.6-4.2, which the organism usually tolerates. These results indicate that the solvent tolerance of Px51T depends upon on energy produced by aerobic respiration.
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Microbiology & Fermentation Technology Notes
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