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Chamber System (chamber + system)
Selected AbstractsGrowth inhibition of Listeria monocytogenes by a nonbacteriocinogenic Carnobacterium piscicolaJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2005L. Nilsson Abstract Aims:, This study elucidates the mechanisms by which a nonbacteriocinogenic Carnobacterium piscicola inhibits growth of Listeria monocytogenes. Methods and Results:,Listeria monocytogenes was exposed to live cultures of a bacteriocin-negative variant of C. piscicola A9b in co-culture, in a diffusion chamber system, and to a cell-free supernatant. Suppression of maximum cell density (0,3·5 log units) of L. monocytogenes was proportional to initial levels of C. pisciola (103,107 CFU ml,1). Cell-to-cell contact was not required to cause inhibition. The cell-free C. piscicola supernatant caused a decrease in L. monocytogenes maximum cell density, which was abolished by glucose addition but not by amino acid, vitamin or mineral addition. The fermentate also gave rise to a longer lag phase and a reduction in growth rate. These effects were independent of glucose and may have been caused by acetate production by C. piscicola. 2D gel-electrophoretic patterns of L. monocytogenes exposed to C. piscicola or to L. monocytogenes fermentate did not differ. Treatment with C. piscicola fermentate resulted in down-regulation (twofold) of genes involved in purine- or pyrimidine metabolism, and up-regulation (twofold) of genes from the regulon for vitamin B12 biosynthesis and propanediol and ethanolamine utilization. Conclusions:, A nonbacteriocinogenic C. piscicola reduced growth of L. monocytogenes partly by glucose depletion. Significance and Impact of the Study:, Understanding the mechanism of microbial interaction enhances prediction of growth in mixed communities as well as use of bioprotective principles for food preservation. [source] Approach to estimation of absorption of aliphatic hydrocarbons diffusing from interior materials in an automobile cabin by inhalation toxicokinetic analysis in ratsJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2010Toshiaki Yoshida Abstract The interior air of an automobile cabin has been demonstrated in our previous studies to be contaminated by high concentrations of a large variety of aliphatic hydrocarbons diffusing from the interior materials. In the present study, the amounts of seven selected aliphatic hydrocarbons absorbed by the car driver were estimated by evaluating their inhalation toxicokinetics in rats. Measured amounts of the substances were injected into a closed chamber system in which a rat had been placed, and the concentration changes in the chamber were examined. The toxicokinetics of the substances were evaluated based on concentration,time courses using a nonlinear compartment model. Their absorption amounts in humans at the levels of actual concentrations in the cabins without ventilation were extrapolated from the results found with the rats. The absorption amounts estimated for a driver during a 2,h drive were as follows: 6,µg/60,kg of human body weight for methylcyclopentane (interior concentration 23,µg/m3 as median value in previous study), 5,µg for 2-methylpentane (36,µg/m3), 13,µg for n- hexane (65,µg/m3), 51,µg for n- heptane (150,µg/m3), 26,µg for 2,4-dimethylheptane (97,µg/m3), 17,µg for n- nonane (25,µg/m3) and 49,µg for n- decane (68,µg/m3). An inverse relationship was found between the exposure and absorption among the substances (e.g. between n-decane and 2,4-dimethylheptane). These findings suggest that not only the exposure concentrations but also the absorption amounts should be taken into account to evaluate the health effects of exposure to low concentrations of volatile compounds as environmental contaminants. Copyright © 2009 John Wiley & Sons, Ltd. [source] Aerosolization as novel sanitizer delivery system to reduce food-borne pathogensLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2005S.-W. Oh Abstract Aims:, As a preliminary experiment on new sanitizer delivery tools, the efficacy of aerosolized sanitizer on food-borne pathogens was investigated in larger model chamber system. Methods:, Peroxyacetic acid and hydrogen peroxide were aerosolized in a model system against artificially inoculated target micro-organisms on laboratory media. Cultures of four different food-borne pathogens were inoculated and affixed onto three different heights (bottom, wall and ceiling), and three different orientations (face-down, vertical and face-down) inside a commercial semi-trailer cabinet (14·6 × 2·6 × 2·8 m). Sanitizer was aerosolized into 2 ,m droplet size fog and treated for 1 h at ambient temperature. Results:, Populations of Bacillus cereus, Listeria innocua, Staphylococcus aureus, and Salmonella typhimurium were reduced by an average of 3·09, 7·69, 6·93 and 8·18 log units per plate respectively. Interestingly, L. innocua, Staph. aureus, and Salm. typhimurium showed statistically not different (P , 0·05) reduction patterns relative to height and orientation that were never expected in a spraying system. Conclusions:, Aerosolized sanitizers diffuse like gaseous sanitizers. Significance and Impact of the Study:, Aerosolization has great potential for use in commercial applications. [source] A numerical evaluation of chamber methodologies used in measuring the ,13C of soil respirationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2009Nick Nickerson Measurement of the ,13C value of soil-respired CO2 (,r) has become a commonplace method through which ecosystem function and C dynamics can be better understood. Despite its proven utility there is currently no consensus on the most robust method with which to measure ,r. Static and dynamic chamber systems are both commonly used for this purpose; however, the literature on these methods provides evidence suggesting that measurements of ,r made with these chamber systems are neither repeatable (self-consistent) nor comparable across methodologies. Here we use a three-dimensional (3-D) numerical soil-atmosphere-chamber model to test these chamber systems in a ,surrogate reality'. Our simulations show that each chamber methodology is inherently biased and that no chamber methodology can accurately predict the true ,r signature under field conditions. If researchers intend to use ,r to study insitu ecosystem processes, the issues with these chamber systems need to be corrected either by using diffusive theory or by designing a new, unbiased ,r measurement system. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||