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71.
Nakano S Maeshima H Matsumura A Ohno K Ueda S Kuwabara Y Yamada T 《Journal of food protection》2004,67(8):1694-1701
A PCR assay for the detection of Bacillus cereus strains able to produce an emetic toxin (cereulide) was developed in this study based on a sequence-characterized amplified region (SCAR) derived from a random amplified polymorphic DNA (RAPD) fragment. One of the RAPD fragments generated was selected, cloned, and sequenced. A set of PCR primers was newly designed from the SCAR obtained (the sequence of the cloned RAPD fragment) and used in this assay. To determine the specificity of the assay, 30 different B. cereus strains, 8 other Bacillus strains (of six species), and 16 other non-Bacillus strains (from 16 genera) were tested. Results were positive for every emetic B. cereus strain and for only one nonemetic B. cereus strain. For all other bacterial strains, results were negative. Bacterial DNA for PCR was prepared by a simple procedure using Chelex 100 resin from the bacterial colony on the agar plate or from culture after growth in brain heart infusion medium. This PCR assay enabled us to detect the bacteria of emetic B. cereus grown on agar plates but not the bacteria of nonemetic B. cereus. To test this PCR assay for the monitoring of the emetic bacteria, 10 to 70 CFU of B. cereus DSM 4312 (emetic) per g of food was inoculated into several foods as an indicator, followed by a 7-h enrichment culture step. Because this PCR assay based on the SCAR derived from the RAPD fragment was able to detect bacterial cells, this assay should be useful for rapid and specific detection of emetic B. cereus. 相似文献
72.
Asakawa M Beppu R Tsubota M Ito K Takayama H Miyazawa K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2005,46(6):251-255
As a part of our studies on paralytic shellfish poison (PSP) accumulation kinetics in bivalves, short-necked clam Tapes japonia was experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days, and the processes of PSP accumulation and bioconversion were investigated: the toxicity level was determined by mouse bioassay and toxin components were identified by high-performance liquid chromatography (HPLC). The strain of A. tamarense used in this study possessed a specific toxicity of 186.7 +/- 81 (mean +/- S.D., n = 5) x 10(-6) MU/cell. Total toxin concentration of this strain was 140.4 +/- 61 (mean S.D., n = 5) fmol/cell. The toxicity level of short-necked clams increased almost in parallel with the abundance of A. tamarense, reaching 1.8, 3.2, 3.8, 3.5 and 4.6 MU/g meat for 2, 4, 6, 8 and 10 days of feeding, respectively. The accumulation rates of PSP toxins, which are the ratio of the total amount of toxins accumulated in the bivalves to the estimated intake in each feeding experiment, were 7.5, 8.1, 5.7, 4.2 and 4.4% for 2, 4, 6, 8 and 10 days, respectively. At the end of each exposure period, many undigested algal cells were found in pseudofeces under microscopic observation. There was a remarkable difference in the relative proportions of the predominant toxin components between A. tamarense and short-necked clams. The most notable difference was the change in the relative amounts of C2 (carbamoyl-N-sulfo-11beta-hydroxysaxitoxin sulfate), GTX1 and GTX 4 during the first two days. In the toxic bivalves, the amount of C2, which is dominant in A. tamarense, decreased to below half a percent after being ingested. Subsequently, the amount of GTX1 in the shellfish meat reached 50.1 mol%, while that of GTX4 decreased to about half of that in A. tamarense. As for the configuration of 11-hydroxysulfate, PSP components in A. tamarense exist almost exclusively as beta-epimers (GTX3, GTX4, C2 and C4), accounting for 72.8 mol% of the total. This contrasts with the case of the short-necked clams, where the beta-epimers represented 25.8, 33.8, 30.8, 36.8 and 28.5 mol% of the total after 2, 4, 6, 8 and 10 days, respectively. PSP components seemed to be converted rapidly at an early stage of the feeding of A. tamarense. 相似文献
73.
Katsutoshi Hori Masahito Ishikawa Mariko Yamada Aisuke Higuchi Yu Ishikawa Hironori Ebi 《Journal of Bioscience and Bioengineering》2011,111(1):31-36
The toluene-degrading bacterium Acinetobacter sp. Tol 5 is highly adhesive through cell-surface nanofibers. Previously, we identified two morphologically distinct nanofibers on Tol 5 cells, namely, nonperitrichate anchor-like and peritrichate pilus-like nanofibers. In the present study, the application of improved electron microscopy techniques enabled discrimination of three distinct types of peritrichate nanofibers on Tol 5 cells. Interestingly, production of these nanofibers was affected by the available growth substrate. Thick, long, straight nanofibers a, which were present on cells grown on toluene, lactate, and ethanol, were not observed on cells grown on triacylglycerol (TAG). In contrast, cells grown on TAG were covered with long, curved nanofibers c, which only existed sparsely on cells grown on toluene, lactate, and ethanol. Thin, short, straight nanofibers b were found densely covering the margin of cells grown on all four growth substrates. SDS-PAGE of Tol 5 cell-surface proteins detected a protein of 17.5 kDa that was expressed at a high level on ethanol, but was undetectable on TAG. Conversely, a 26 kDa protein was identified that was exclusively expressed on TAG, but was only faintly expressed by cells grown on the other substrates. Based on N-terminal amino acid sequences, the 17.5 and 26 kDa proteins were identified as the major subunits of type 1 and Fil pili, respectively, which are typical bacterionanofibers. From these results, we deduced that nanofibers a and c are type 1 and Fil pili, respectively. The adhesiveness of Tol 5 cells was low only when they were grown on TAG. 相似文献
74.
Paudyal H Pangeni B Inoue K Kawakita H Ohto K Harada H Alam S 《Journal of hazardous materials》2011,192(2):676-682
Adsorption gels for fluoride ion were prepared from orange waste by saponification followed by metal loading. The pectin compounds contained in orange waste creates ligand exchange sites once it is loaded with multi-valent metal ions such as Al3+, La3+, Ce3+, Ti4+, Sn4+, and V4+ to be used for fluoride removal from aqueous solution. The optimum pH for fluoride removal depends on the type of loaded metal ions. The isotherm experiments showed the Langmuir type monolayer adsorption. Among all kinds of metal loaded gels tested, Al loaded gel appeared to exhibit the most favorable adsorption behavior. The adsorption kinetics of fluoride on loaded gel demonstrated fast adsorption process. The presence of NO3−, Cl− and Na+ ions has negligible effect on fluoride removal whereas SO42− and HCO3− retarded the fluoride removal capacity in some extent. Fluoride removal at different adsorbent doses showed that fluoride concentration can be successfully lowered down to the acceptable level of environmental standard. The fluoride adsorption mechanism was interpreted in terms of ligand exchange mechanism. The complete elution of adsorbed fluoride from the gel was successfully achieved using NaOH solution. 相似文献
75.
Yoji Sunagawa Katsutoshi Yamamoto Hideyuki Takahashi Atsushi Muramatsu 《Catalysis Today》2008,132(1-4):81
In the present study, the liquid-phase reductive deposition as a novel nanoparticle synthesis method has been investigated and its application to supported noble metal catalyst preparation was also focused. As a result, the maximum loading of Pt was around 20 wt% with keeping the particle size below 2 nm, by the present technique based on the liquid-phase reduction method. The selective reductive deposition is characteristically performed by the adsorption of metal ion or complexes on the surfaces and hereby the reduction. Namely, the initial adsorption of metal ions or complexes is the key point of this technique. Hence, key points of this method are: (1) precise control of the metal complex by adjusting solute conditions, such as composition and structure of metal complex, (2) storing of the suspension until the equilibrium composition and (3) aging suspension at controlled temperature. The most important is the first one, as the adsorption of specific metal complex results in the generation of precursor solid on the surfaces of the supporting materials. By this novel method, not only Pt but also Au nanoparticles supported on various carriers were successfully obtained. 相似文献
76.
77.
Hayashi Masahiro; Tomita Masahiro; Yoshizato Katsutoshi 《Protein engineering, design & selection : PEDS》2002,15(5):429-436
Interleukin-2 (IL-2) is a potent activator of cellular immunityand has been utilized as an immunotherapeutic agent. We stablyimmobilized human IL-2 to collagen by covalently binding itto the N-terminus of human type III collagen (3A1) as IL2-3A1chimeric protein using recombinant technology. The present studywas aimed at liberating IL-2 from the immobilized chimeric proteinby treating the chimera with bacterial collagenase. These IL2-3A1chimeras were synthesized in insect cells which had been infectedwith baculovirus vectors carrying IL2-3A1 cDNA. The IL2-3A1protein produced was shown to be in a pepsin-resistant triplehelical structure and exhibited IL-2 activity to a similar extentas IL-2 itself. IL2-3A1 could be immobilized on the surfaceof plastic dishes by incubating it in the dishes. The IL-2 regionof the immobilized IL2-3A1 was liberated to culture media bycollagenase treatment and this freed IL-2 stimulated the growthof lined T cells. Thus, IL2-3A1 chimeric protein could be utilizedas an IL-2 deliverer whose T cell mitogenic activity can beliberated by a collagenolytic environment. 相似文献
78.
Kodama T Endo K Ara K Ozaki K Kakeshita H Yamane K Sekiguchi J 《Journal of Bioscience and Bioengineering》2007,103(1):13-21
The Bacillus subtilis spo0A mutant is an adequate host for extracellular protein production (e.g., alpha-amylase). However the mutant was prone to cell lysis. SDS-PAGE and zymography of cell wall lytic proteins indicated that the spo0A mutant contained high amounts of two major autolysins (LytC [CwlB] and LytD [CwlG]) and two minor cell wall lytic enzymes (LytE [CwlF] and LytF [CwlE]). On the other hand, the expression of eight extracellular protease genes was very poor or absent in the spo0A mutant. An eight-extracellular-protease-deficient mutant (Dpr8 strain) was constructed and the strain also exhibited cell lysis. The autolysins from the spo0A mutant were degraded by the supernatant of the wild type but not degraded by that of the Dpr8 mutant. These results suggest that the extensive cell lysis of the spo0A mutant was partially caused by the stability of autolysins via the decrease of the extracellular proteases. The introduction of a major autolysin and/or SigD mutations into the spo0A mutant was effective for preventing cell lysis. 相似文献
79.
Kanjana Khunathai Katsutoshi Inoue Keisuke Ohto Hidetaka Kawakita Minoru Kurata Kinya Atsumi 《溶剂提取与离子交换》2013,31(3):320-334
A biomass waste of microalgae was chemically modified by immobilizing the functional group of polyethyleneimine to prepare a new type of adsorbent. The adsorption test revealed that this adsorbent exhibited remarkably high selectivity for Pd(II) and Pt(IV) over base metal ions in HCl solution. From the adsorption isotherm, its maximum adsorption capacity for Pd(II) and Pt(IV) was evaluated as 2.0 and 0.8 mmol/g, respectively. This adsorbent also exhibited high affinity and selectivity for Pd(II) and Pt(IV) even in the presence of high concentrations of base metals in actual leach liquor. 相似文献
80.
The extraction equilibrium of mercury(II) from aqueous ammonium thiocyanate solution with triisobutyl-phosphine sulfide(=TIBPS=S¯) in toluene has been measured at 303 K. It was found that mercury(II) is extracted according to a solvation reaction by TIBPS as a mercurydl) :TIBPS 1:2 complex, Hg(SCN)2S2, as follows: The extraction equilibrium constant, Ke, was evaluated as Ke = 1.8 × 106 (dm3/mol)2. 相似文献