Antimicrobial effect of spices and herbs on Vibrio parahaemolyticus

The antimicrobial effects of spices and herbs from 18 plant species were examined on a foodborne pathogen, Vibrio parahaemolyticus, with the use of combinations of temperatures and nutrient levels. Basil, clove, garlic, horseradish, marjoram, oregano, rosemary, and thyme exhibited antibacterial activities at incubation of 30 degrees C, while with the exception of horseradish, the same spices and additional 7 species exhibited the activities at 5 degrees C. The lowest MIC (minimum inhibitory concentration) was 0.125% observed in clove and marjoram at 30 degrees C in a nutrient rich medium. Lowering of incubation temperature produced little effect on the MICs except for turmeric. The decreasing of the MIC in turmeric appeared to be basically attributed to the sensitivity of the bacterium to coldness. In nutrient poor medium, the lowest was 0.001 and 0.00025% in marjoram at 30 degrees C and at 5 degrees C, respectively. The sensitivity to several spices and herbs was similar among different clinical serotypes including the emerging strain O3:K6. These results suggest that the spices and herbs can be practical for protecting seafood from the risk of contamination by V. parahaemolyticus and used in hurdle technology with low temperature.     

Characteristics and modeling of Escherichia coli growth in pouched food

Characteristics of the growth kinetics of Escherichia coli cells in pouched mashed potatoes under various conditions were studied with a mathematical model. Bacterial cells were inoculated in sterile mashed potatoes and then sealed in vinyl pouches, in which a very small amount of air was included. The growth curves of cells in the pouched mashed potatoes at constant temperature (12-34 degrees C) were sigmoidal with time on a semi-logarithmic plot and were successfully described with a new logistic model recently developed by us. The rate constant of growth showed a highly linear relationship to the temperature with the square-root model, and the lag period was longer at lower temperatures. The growth curve in glass tubes containing a large volume of air was similar to that in pouches, showing that the rate of growth was not affected by the volume of the surrounding air. The growth curves in pouched mashed potatoes were very similar to those in nutrient broth or on the surface of nutrient agar, which we previously reported. These results suggested that the growth kinetics of the bacterial cells under various conditions of rich nutrition might be almost identical, and can be described with a simple growth model like ours.     

Characteristic long-chain fatty acid of Pleurocybella porrigens

As part of an investigation on the chemical constituents and contaminants of the basidiomycete Pleurocybella porrigens (Japanese name: Sugihiratake), we analyzed the UV-detected constituents of this mushroom using HPLC. One of the major UV peaks detected was isolated and identified as a-eleostearic acid, a long-chain fatty acid with a conjugated triene moiety, based on the results of spectroscopic methods. alpha-Eleostearic acid was concluded to be a characteristic fatty acid of P. porrigens, because it was not detected in eight other edible mushrooms examined. Free long-chain fatty acids in P. porrigens and other edible mushrooms were analyzed by HPLC after derivatization with acidic 2-nitrophenylhydrazine hydrochloride. Oleic acid was the main fatty acid in P. porrigens, and saturated long-chain fatty acids such as linoleic acid, palmitic acid, and stearic acid, together with a-eleostearic acid, were also detected.     

Purification and characterization of enzyme responsible for N-myristoylation of octapeptide in aqueous solution without ATP and coenzyme a from Pseudomonas aeruginosa

The enzyme that catalyzes N-acyl linkage between myristic acid and the NH(2)-terminal glycine residue of the octapeptide Gly-Asn-Ala-Ala-Ala-Ala-Arg-Arg-NH(2) in aqueous solution without ATP and coenzyme A was found in Pseudomonas aeruginosa. The enzyme was purified from cell-free crude extract using DEAE-Cellulose, Sephadex G-200, CM-Sephadex C-50, and hydroxyapatite column chromatographies, and then purified approximately 1900-fold with about 1.5% recovery of enzyme activity from the crude extract. Finally, the purified enzyme showed a main band on SDS polyacrylamide gel electrophoresis after staining with Coomassie Brilliant Blue. The band corresponded to a molecular mass of approximately 60 kDa. The K(m)s of the purified enzyme for the substrate myristic acid and the octapeptide were 0.36 and 2.6 mM, respectively. When myristoyl-CoA instead of myristic acid was used as the substrate for the enzyme reaction, myristoyl octapeptide could be synthesized as observed in the case of myristic acid. The K(m) of myristoyl-CoA was 0.17 mM.     

Precise metabolic flux analysis of coryneform bacteria by gas chromatography-mass spectrometry and verification by nuclear magnetic resonance

Precise metabolic flux analysis (MFA) by gas chromatography-mass spectrometry (GC-MS) and computer calculation was performed, and the consistency of the estimated results was verified by independently performed nuclear magnetic resonance (NMR) analysis. The precise estimation of flux by the integration method of the mass isotopomer signal, defined as the coefficient of variance (CV) of multiple determination, was investigated, and the results estimated using different data sets with the same magnitude of error were confirmed. The CV of multiple determinations was sufficiently small to discuss and compare the fluxes of a metabolic pathway. The estimated fluxes using the GC-MS data were cross-validated with the NMR data that were independently measured and not used for MFA. The developed method was successfully applied to the MFA of the growth phase of two different glutamate-producing coryneform bacteria, Corynebacterium glutamicum and C. efficiens. The difference in the growth rate between these two bacterial species was discussed while considering the results of MFA, including forward and backward (exchange) fluxes.     

Decomposition of extremely hard-to-degrade animal proteins by thermophilic bacteria

Hard-to-degrade animal proteins are ubiquitously present throughout animal bodies. Enormous numbers of these proteins generated in the meat industry are converted to industrial wastes, the disposal of which is tremendously difficult. Most hard-to-degrade animal proteins are currently disposed of by incineration; however, this method has ecological disadvantages in terms of an apparent energy loss and the production of a large amount of carbon dioxide. As a result, an innovative solution to these problems has been sought. In this review, we focus on the degradation of three hard-to-degrade animal proteins (extracellular matrix proteins, collagen in particular, keratin, and prion proteins) and discuss the decomposing capability of thermophilic bacteria. These proteins are strongly resistant to proteinases because of their structural features; therefore, new approaches employing bacterial proteases with strong activity and broad specificity are required for practical application.     

Building maps of local apparent conductivity of the epicardium with a 2-D electrophysiological model of the heart

In this paper, we address the problem of estimating the parameters of an electrophysiological model of the heart from a set of electrical recordings. The chosen model is the reaction-diffusion model on the transmembrane potential proposed by Aliev and Panfilov. For this model of the transmembrane, we estimate a local apparent two-dimensional conductivity from a measured depolarization time distribution. First, we perform an initial adjustment including the choice of initial conditions and of a set of global parameters. We then propose a local estimation by minimizing the quadratic error between the depolarization time computed by the model and the measures. As a first step we address the problem on the epicardial surface in the case of an isotropic version of the Aliev and Panfilov model. The minimization is performed using Brent method without computing the derivative of the error. The feasibility of the approach is demonstrated on synthetic electrophysiological measurements. A proof of concept is obtained on real electrophysiological measures of normal and infarcted canine hearts.     

Novel expansion/shrinkage modulation of 2D layered MOF triggered by clathrate formation with CO(2) molecules

Crystal-to-crystal transformation from a 3D interpenetrated-type MOF {[Cu(BF(4))(2)(bpy)(H(2)O)(2)] (bpy)} (1) to a 2D square-grid-type [Cu(BF(4))(2)(bpy)(2)] (2) (bpy = 4,4'-bipyridine) was observed. It was derived from dehydration and confirmed by in situ FT-IR, TG, and elemental analysis. Moreover, we elucidate the novel expansion/shrinkage dynamic modulation of 2 triggered by clathrate formation with gas molecules.     

Room-temperature miscibility gap in LixFePO4

The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO(4), solves these problems, but has a kinetic problem involving strong electron/hole localization. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe(3+)PO(4)/LiFe(2+)PO(4) two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe(3+)/Fe(2+) mixed-valent intermediate LialphaFePO4 and Li1-betaFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be alpha=0.05 and 1-beta=0.89. The corresponding solid solution ranges outside the miscibility gap (0相似文献   

Changes in vascular leakage and expression of angiopoietins in the corpus luteum during pregnancy in rats

The present study investigates changes in blood vessel stability and its regulation in the corpus luteum (CL) during pregnancy in the rat. First, blood vessel stability in the CL was evaluated during pregnancy based on vascular leakage, which was quantified by the Evans blue assay. Vascular leakage was highest on day 3, thereafter decreased until day 15 and increased again on day 21. Secondly, to study the regulation of vascular leakage, the expression of angiopoietins was examined in the CL during pregnancy. Angiopoietin-1 (Ang-1) effects maturation and stabilization of newly formed blood vessels, while Ang-2 produces the opposite effect by allowing vascular remodeling. An immunohistochemical study showed both Ang-1 and Ang-2 expression in luteal cells. mRNA and protein levels of Ang-1 were significantly higher on days 12 and 15 than those on days 3 and 21, whereas there was no significant change in Ang-2 expression. Since estradiol contributes to CL development during mid-pregnancy, we finally studied whether estradiol regulates vascular leakage and angiopoietin expression. Rats undergoing hypophysectomy and hysterectomy (hypox-hect) on day 12 were treated with estradiol until day 15. Vascular leakage was increased and Ang-1 expression was decreased by hypox-hect, and these effects were completely reversed by estradiol treatment. In conclusion, blood vessel stability in the CL is likely to be associated with CL development and CL regression, and may be regulated by angiopoietins. Estradiol contributes to blood vessel stabilization in the CL during mid-pregnancy, which is associated with an increase in Ang-1 expression.