Identification of Bacillus spp., Escherichia coli, Salmonella spp., Staphylococcus spp. and Vibrio spp. with 16S ribosomal DNA-based oligonucleotide array hybridization

Rapid identification of the genus and species of bacteria in foods and clinical specimens is important. In this report, DNA sequences of bacterial 16S rDNA were used to develop the oligonucleotide array for the identification of bacterial strains of Bacillus spp., Escherichia coli, Salmonella spp., Staphylococcus spp. and Vibrio spp. Most of these bacterial strains may cause food-borne outbreaks or sporadic cases. A rapid (<4 h) detection method that used universal PCR primers to amplify the variable regions of bacterial 16S rDNA, followed by reverse hybridization of the PCR products, which were biotin labeled, to the oligonucleotides arrayed on the chip was developed. Fifteen oligonucleotide probes were selected and spotted on the nylon strip to determine the array hybridization patterns. It was successful in discriminating Bacillus spp., E. coli, Salmonella spp., Staphylococcus spp. and Vibrio spp. with identification, in general, to the genus level, not species level. As 182 randomly selected strains were assayed, the detection rate was found higher than 98%. Except for 3 strains, the remaining 179 strains were correctly identified and no cross reactions were observed. These 179 strains generated five hybridization patterns. Adding more oligonucleotide probes to the array may allow the detection of more bacterial genera and species without significantly increasing the complexity or cost.     

Analysis of PCR-based methods for characterization of Listeria monocytogenes strains isolated from different sources

Listeria monocytogenes strains, isolated from various sources (food, environment, and animals), were used to test different PCR-based methods to investigate their capability to define the strain origin. RAPD-PCR with three primers and the SAU-PCR method, in which the DNA was first digested with the Sau3A restriction endonuclease and then amplified with a primer designed on the restriction site, were carried out, and the profiles obtained were used to perform cluster analysis. Based on the cluster analysis of Listeria spp. strains, obtained from international collections, the coefficient of similarity was selected. The results obtained showed that the methods tested in the study gave different levels of differentiation between the strains tested. The RAPD protocol using the P1254 primer and the SAU-PCR gave appreciable results only for strains isolated from animals and from a food processing plant in two different periods of the year 2003. Better differentiation was observed using the RAPD-PCR with primer D8635. As a matter of fact, it was able to distinguish L. monocytogenes obtained from different species of animals, different food samples and strains from the same production plant isolated in different periods of the year. Also primer M13 gave positive results, but the coefficient of similarity to use had to be increased to 80%. On the basis of the results observed, RAPD-PCR with primers D8635 and M13 should be considered reliable tools for epidemiological investigations focusing on L. monocytogenes.     

High-performance liquid chromatography multiresidue method for the determination of N-methyl carbamates in fruit and vegetable juices

A rapid multiresidue method has been developed for the analysis of N-methylcarbamate insecticides (oxamyl, methomyl, propoxur, carbofuran, carbaryl, and methiocarb) in fruit and vegetable juices. The method is based on the adsorption of the N-methyl carbamates in Florisil and the subsequent extraction of pesticides using a low volume of acetone. Residue levels in juice were determined by reversed-phase high-performance liquid chromatography with fluorescence detection after postcolumn derivatization. The separation of carbamates is performed on a C8 column with water-methanol as mobile phase. Recovery studies were performed at 500-, 100-, and 10-ng/ml fortification levels, and average recoveries obtained for carbamates ranged from 79 to 109%, with relative standard deviations between 1.4 and 9.9%. The method was found to be linear over the range assayed from 10 to 1,000 ng/ml, and the detection limits for carbamates varied from 0.8 to 1.9 ng/ml.     

Quantitative structure-activity relationship models for prediction of the toxicity of polybrominated diphenyl ether congeners

Levels of polybrominated diphenyl ethers (PBDEs) are increasing in the environment and may cause long-term health problems in humans. The similarity in the chemical structures of PBDEs and other halogenated aromatic pollutants hints on the possibility that they might share similar toxicological effects. In this work, three-dimensional quantitative structure activity relationships (3-D-QSAR) models, using comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA), were built based on calculated structural indices and a reported experimental toxicology index (aryl hydrocarbon receptor relative binding affinities, RBA) of 18 PBDEs congeners, to determine the factors required for the RBA of these PBDEs. After performing leave-one-out cross-validation, satisfactory results were obtained with cross-validation O2 and R2 values of 0.580 and 0.995 by the CoMFA model and 0.680 and 0.982 by the CoMSIA model, respectively. The results showed clearly that the nonplanar conformations of PBDEs result in the lowest energy level and that the electrostatic index was the main factor reflecting the RBA of PBDEs. The two QSAR models were then used to predict the RBA value of 46 PBDEs for which experimental values are unavailable at present.     

水贴处理的是与非

有人说我睡着了都会贴水贴纸。这种说法不能说完全正确，但我差不多困得快迷糊了也能贴水贴纸，这却是真的，因为贴水纸是我在模型制作中最熟悉，最喜欢的步骤。     

Prolonging the viability of Lactobacillus plantarum through the addition of prebiotics into the medium

Abstract: This article reports on the effects of prebiotics on the growth/death kinetics, metabolism, and biomass production by 2 strains of Lactobacillus plantarum (c19 and DSMZ 2601, isolated from table olives and purchased from a Public Collection, respectively). The research was divided into 3 different steps, in order to highlight the optimal combination for cell viability and experiments were performed under the conditions of an accelerated shelf life test; thus, 3 combinations were pointed out (fructooligosaccharides [FOS], 5 g/L; glucose + inulin, 2.5 + 2.5 g/L; glucose + FOS, 2.5 + 2.5 g/L). A sample containing only glucose was used as control. The results highlighted that the 3 combinations aforementioned prolonged cell viability over the time both under low and high inoculum conditions (3 and 9 log CFU/mL, respectively); however, FOS alone caused a reduction of biomass production, even if cell number was not affected by this compound. Therefore, as a final result of this research, the combination glucose + FOS could be proposed as a suitable mean to achieve an optimal production of biomass and prolong cell viability over the time. Practical Application: Food producers require a prolonged viability of probiotic bacteria in functional foods; this goal is usually achieved by refrigeration. In this article, the prolongation of cell viability through the addition of prebiotics was proposed.     

Immunochromatography for the rapid determination of cadmium concentrations in wheat grain and eggplant

BACKGROUND: A simple and quick on‐site test for trace levels of cadmium (Cd) in food is needed because of the human toxicity of this heavy metal. We developed an immunochromatography kit which uses the antigen‐antibody complex reaction between the Cd–ethylenediaminetetraacetic acid (Cd–EDTA) complex and an anti‐Cd–EDTA antibody. We previously reported the successful use of this kit to determine Cd concentrations in brown rice with respect to the international standard: 0.4 mg kg^?1. Here, we measured, using this immunochromatography kit, Cd concentrations in crops with lower international standards than rice. RESULTS: Cadmium extracted with 0.1 mol L^?1 HCl from wheat grain and fresh eggplant was purified sufficiently using an ion‐exchange column treatment. Appropriate HCl extraction rates and dilution rates for the column eluate were selected; Cd concentrations in wheat grain and fresh eggplant were determined successfully by immunochromatography with respect to the international standards of 0.2 mg kg^?1 and 0.05 mg kg^?1 fresh weight, respectively. CONCLUSION: Approximate Cd concentrations in wheat grain and fresh eggplant can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available. Copyright © 2011 Society of Chemical Industry     

采用乙二醛—二醇工艺时无甲醛耐久压烫整理用的低温、中温和高温催化剂

乙二醛与棉反应形成纤维素乙缩醛,这是产生棉交键的一种方法,它无需使用会释放甲醛的甲醛或N-羟甲基试剂。最近的工作已表明,乙二醛赋予的交联工艺的效率和耐久压烫(DP)性能的级别由于二醇的存在而大大提高,这看来它可改变交联反应和形成的交键结构。此外,当棉用乙二醛在空气中在酸性催化剂存在下加热时,二醇可大大抑制泛黄的发生。     

色彩浪漫风

现如今聪明的男人懂得用时尚金饰达到目的,聪明的女人懂得用金饰时尚武装自己。金饰已成为时尚男女争相追捧的目标。2004年金饰大潮流,吸纳了欧美珠宝设计大师们的最新理念,旨在以黄金打造消费者“甜美的生活感受”。今年流行的珠宝首饰设计,皆流动着喜悦明朗的气息。设计者们结合生动活泼的色彩、充满幽默感的想象力、飞扬的活力,传达对甜美生活的憧憬和赞颂。“放轻松,尽情享受生活与生命的美好!”——这是今年金饰设计最重要的创作精神。随着2004年K-gold时尚由欧洲席卷亚洲,今年金饰设计师们做出了更多大胆创新的尝试,把不同颜色的K-gold,配搭各款新颖的物料,如以黄金、白色K金、玫瑰金或青金配搭半宝石、瓷釉、彩珠、贝壳,以及色彩美轮美奂的鳄鱼皮。散发着温暖光芒的金饰,加上色泽如彩虹般漂亮的创意物料,为时代女性带来如糖果般精致美丽的浪漫金饰。2004年金饰时尚共划分为三大设计潮流:“梦游仙境”、“飞跃华丽”、“视觉盛宴”。     

Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site

Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.