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71.
The capacity for anaerobic decolorization of a sulfonated azo dye, Congo Red, by a strain of a sulfate-reducing bacterium
was evaluated. After optimizing the growth rate of the bacteria on a simple carbon source and terminal electron acceptor pair,
lactate and sulfate, respectively, the effect of the dye concentration on their growth rate was analyzed. The decolorization
rate was affected by the dye concentration in the growth medium. The azo-bond cleavage mechanism of reductive decolorization
with the formation of benzidine was consistent with the results, as this metabolite was identified by high-performance liquid
chromatography. Several fractions of the culture medium, including lysed cell extracts, were examined for the capacity to
reduce the azo dye. This reduction capacity was found in the culture medium in which the cells had previously grown. The results
showed that the mechanism of reductive decolorization of this sulfonated azo dye was extracellular and nonenzymatic, consistent
with the production of sulfide anion by the microorganisms while growing on lactate and sulfate. The sulfide anions were the
cause of the reduction leading to the disappearance of color in the medium. To increase the rate of decolorization, the presence
of ferrous ion was also necessary together with the lactate and sulfate substrates. 相似文献
72.
Scientific evidence in the prevention and treatment of various disorders is accumulating regarding probiotics. The health
benefits supported by adequate clinical data include increased resistance to infectious disease, decreased duration of diarrhea,
management of inflammatory bowel disease, reduction of serum cholesterol, prevention of allergy, modulation of cytokine gene
expression, and suppression of carcinogen production. Recent ventures in metabolic engineering and heterologous protein expression
have enhanced the enzymatic and immunomodulatory effects of probiotics and, with time, may allow more active intervention
among critical care patients. In addition, a number of approaches are currently being explored, including the physical and
chemical protection of cells, to increase probiotic viability and its health benefits. Traditional immobilization of probiotics
in gel matrices, most notably calcium alginate and κ-carrageenan, has frequently been employed, with noted improvements in
viability during freezing and storage. Conflicting reports exist, however, on the protection offered by immobilization from
harsh physiologic environments. An alternative approach, microencapsulation in “artificial cells,” builds on immobilization
technologies by combining enhanced mechanical stability of the capsule membrane with improved mass transport, increased cell
loading, and greater control of parameters. This review summarizes the current clinical status of probiotics, examines the
promises and challenges of current immobilization technologies, and presents the concept of artificial cells for effective
delivery of therapeutic bacterial cells. 相似文献
73.
在pH4.3的B-R缓冲体系中,用微相吸附-光谱修正技术[1]研究了茜素红(ARS)与牛血清白蛋白(BSA)、人血清白蛋白(HSA)的结合反应。其吸附结合常数分别为:KBSA-ARS=3.950×104,KHSA-ARS=4.377×104。染料与蛋白的最大结合数分别为NARS∶NBSA=9∶1,NARS∶NHSA=7∶1。经光谱修正技术计算结合产物的实际摩尔吸光系数分别为εBSA-ARS(537nm)=2.517×104L.mol-1.cm-1,εHSA-ARS(519nm)=2.051×104L.mol-1.cm-1,检出限BSA为19mg/L,HSA为23mg/L。经探讨该结合反应机理符合Langmuir吸附聚集反应方程。 相似文献
74.
The interaction of Methylthymol Blue(MTB)-Zinc(Ⅱ) compound and Alizarin Red S(ARS)-Aluminum(Ⅲ) compound with Bovine serum albumin (BSA) was investigated by UV-Vis spectrophotometric method in acidic buffer solution. MTB-Zn(Ⅱ)-BSA was a blue color compound, which possesses maximum absorption at 613 nm with 172 nm, 174 nm and 18 nm of red shift compared to the MTB, MTB-BSA and MTB-Zn(Ⅱ) complexes respectively. Dual wavelength substantial amount ratio method, balance dialysis substantial amount ratio method and unity wavelength substantial amount ratio method were compared. The following results were obtained: the apparent molar absorptivity of MTB-Zn(Ⅱ) with BSA was ε=2.20×104 L·mol-1·cm-1. Conditional proportion were defined, nMTB∶nZn(Ⅱ)∶nBSA=2∶2∶1; condition combination constant, K=2.07×1010. Combination proportion were defined, nARS∶nAl(Ⅲ)∶nBSA=6∶4∶1. Condition equilibrium constant of reaction of ARS-Al(Ⅲ) with BSA was K=8.80×108. The apparent molar absorptivity of ε=2.65×104 L·mol-1·cm-1. It is suggested that combination between BSA and MTB-Zn(Ⅲ) is due to coordination force. That combination between BSA and ARS-Al(Ⅲ) is due to the coordination bond and electrostatic force. 相似文献
75.
76.
J. Monaselidze Ya. Kalandadze D. Khachidze 《Journal of Thermal Analysis and Calorimetry》1996,46(2):431-440
The influence of mitoxantron (M) and benz(a)pyrene (BP) on chromatin DNA in composition of spleen and liver tissues and cells of BALB/c mice were studied using a high-sensitive differential scanning microcalorimeter. It was established that BP can cause a) the specific breaks in inactive chromatin DNA chain and unfolding of the whole domain (a loop of chromatin) which should lead to uncontrolled genome activation; b) the breaks in the DNA double-helix creating short duplexes.M at low doses, interacting with naked linker DNA of tumor restores the chromatin structure, at high doses or at repeated injections,M causes the disturbance of chromatin structure. 相似文献
77.
Naofumi Terada Minoru Morimoto Hiroyuki Saimoto Yoshiharu Okamoto Saburo Minami Yoshihiro Shigemasa 《先进技术聚合物》2003,14(1):40-51
Oxidized chitosan derivatives with various degrees of oxidation (DS, 0.1–1.0) were prepared by the treatment of chitosan with CrO3/aq HClO4 or by the oxidation of 3‐O‐ and N‐protected chitosan with 30% aq H2O2/Na2WO4 followed by 3‐O‐ and N‐deprotection. The oxidized products were then N‐acetylated with Ac2O in order to improve their water‐solubility. Although the oxidized chitosan derivative of DS 0.28 and the degree of N‐acetylation of chitosan (DA) 38% was insoluble in the pH 3–8 region, that of DS 0.26 and DA 76% was soluble in the neutral pH range. The newly‐prepared acetylated and oxidized chitosan derivatives were found to suppress the chemiluminescence response of inflammatory cells such as canine polymorphonuclear cells (PMNs). Analysis by the surface plasmon resonance method revealed that the bind and release behavior of PMNs to acetylated oxidized chitosan derivatives was similar to that against carboxymethylated chitosan derivatives. The amount of water‐soluble chitosan derivative bound to cytokine IL‐8 was found to be affected by the structural and electronic features of the chitosan substituents in the chitosan chain. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
78.
Xirong Huang Nianqin Jie Shuhua Han Wenjuan Zhang Jianping Huang 《Mikrochimica acta》1997,126(3-4):329-333
The coordination reactions of bromopyrogallol red (BPR) with tri- and hexavalent chromium in the presence of cetyltrimethylammonium bromide (CTAB) have been studied by absorption spectrometry. Results show that the reactions of Cr(VI) and Cr(III) with BPR in the absence or presence of CTAB have different temperature dependences. The reaction mechanism of Cr(VI) is that Cr(VI) is first reduced by BPR to Cr(III) and then the Cr(III) produced reacts with BPR. Based on the study on the coordination reactions and the effects of surfactants upon them, a simple, rapid, sensitive and accurate method for Cr speciation has been developed. Over the range of 0–8 g Cr(VI) or 0–12g Cr(III) per 25ml final volume, the calibration curve is linear with a detection limit of 3.5 × 10–7 mol/1 for Cr(VI) or 4.4 × 10–7 mol/1 for Cr(III). 相似文献
79.
Congo red (CR) is an azo dye which not only preferentially binds to elastin, an extracellular matrix protein found in the media of arterial vessel walls, but also fluoresces when it binds to this protein. Protein solubilization data following laser irradiation of elastin:CR suspensions determined that the amount of elastin solubilized by laser irradiation increased with the increase in CR. The saturation point of CR to elastin was attained when 400 g CR was added to 20 mg elastin suspension. When 20 ml of a 5% CR solution in 5% dextrose was administered intravenously, the CR was absorbed in levels sufficient to produce fluorescence of the main arteries in rabbits. Layers of tissue both in the media of the vessels and at the endothelial/intimal interface were clearly differentiated. Therefore, the elastin:CR complex appears to be an ideal system in which the elastin fluorescence could aid in distinguishing between normal and diseased tissue in certain pathological conditions, such as atherosclerosis and some types of breast tumors. 相似文献
80.
Weiland P 《Applied biochemistry and biotechnology》2003,109(1-3):263-274
The production of biogas for reducing fossil CO2 emissions is one of the key strategic issues of the German government and has resulted in the development of new process
techniques and new technologies for the energetic use of biogas. Progress has been made in cultivating energy crops for biogas
production, in using new reactor systems for anaerobic digestion, and in applying more efficient technologies for combined
heat and power production. Recently, integration of fuel cells within the anaerobic digestion process was started, and new
technologies for biogas upgrading and conversion to hydrogen were tested. This article describes the trends in Germany for
achieving more efficient energy production. 相似文献