Modulation of affinity of a marine pseudomonad for toluene and benzene by hydrocarbon exposure

Trace (microgram liter-1) quantities of either toluene or benzene injected into an amino-acid limited continuous culture of Pseudomonas sp. strain T2 were utilized immediately with affinities of 2.6 and 6.8 liters g of cells-1 h-1, respectively, and yielded large amounts of organic products, carbon dioxide, and cells. The immediate utilization of hydrocarbons by hydrocarbon-deprived organisms helps to establish the nutritional value of nonpolar substrates in the environment. The observation of small Michaelis constants for toluene transport led to tests of metabolic competition between hydrocarbons; however, competitive inhibition of toluene metabolism was not found for benzene, naphtalene, xylene, dodecane, or amino acids. Benzene and terpenes were inhibitory at milligram liter-1 concentrations. Toluene was metabolized by a strongly inducible system when compared with benzene. The capacity of toluene to effect larger affinity values increased with exposure time and concentration. The kinetics of induction suggested saturation phenomena, resulting in an induction constant, K(ind), of 96 μg of toluene liter-1. Maximal induction of amino-acid-grown cells required about 80 h, with the affinity reaching 317 liters g of cells-1 h-1

Erasmus Language students in a British University – a case study

Students’ assessment of their academic experience is actively sought by Higher Education institutions, as evidenced in the National Student Survey introduced in 2005. Erasmus students, despite their growing numbers, tend to be excluded from these satisfaction surveys, even though they, too, are primary customers of a University. This study aims to present results from bespoke questionnaires and semi-structured interviews with a sample of Erasmus students studying languages in a British University. These methods allow us insight into the experience of these students and their assessment as a primary customer, with a focus on language learning and teaching, university facilities and student support. It investigates to what extent these factors influence their levels of satisfaction and what costs of adaptation if any, they encounter. Although excellent levels of satisfaction were found, some costs affect their experience. They relate to difficulties in adapting to a learning methodology based on a low number of hours and independent learning and to a guidance and support system seen as too stifling. The results portray this cohort’s British University as a well-equipped and well-meaning but ultimately overbearing institution, which may indicate that minimising costs can eliminate some sources of dissatisfaction

Kinetics Of Dissipation And Biodegradation Of Crude Oil In Alaska's Cook Inlet

Abstract The results of a study to quantitatively define the magnitude of oil pollution problems in Alaska's Cook Inlet are reported. Physical dissipation and biodegration rates were determined and combined with estimates of hydrocarbon input rates to assess the fate of oil in Cook Inlet. The question of accumulation of crude oil components within the Inlet is considered from the above results and by direct analysis. Results indicate that hydrocarbon accumulation is less than our present limits of detection. Cook Inlet flushing is 90 per cent complete in 10 months. Experimental results show that unsupplemented Cook Inlet water effectively degrades Cook Inlet crude, that this biodegradation is essentially complete in the order of a few months, and that the biodegration capacity of Cook Inlet is large. Thus biodegration is more important than physical flushing in removing hydrocarbon pollutants from Cook Inlet. The methods and results are discussed in terms of their applicability to other areas.</jats:p

Precision measurement of the proton spin structure function g(p1)

We have measured the ratio (gi) /F(gi) over the range 0.029 ( x ( 0.8 and 1.3 (Q+/- ( 10 (GeV/c) using deep-inelastic scattering of polarized electrons from polarized ammonia. An evaluation of the integral fo g+/_ (x, Q2) dx at fixed Q2 = 3 (GeV/c)2 yields 0.127 +/- 0.004(stat) +/- 0.010(syst), in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160 +/- 0.006. In the quark-parton model, this implies Aq = 0.27 +/- 0.10.This work was supported by Department of Energy Contracts No. DE-AC05-84ER40150 (CEBAF), No. W-2795-Eng-48 (LLNL), No. DE-AC0376SF00515 (SLAC), No. DE-FG03-88ER40439 (Stanford), No. DE-FG05-88ER40390 and No. DEFG05-86ER4026 (Virginia), and No. DE-AC02-76ER00881 (Wisconsin); by National Science Foundation Grants No. 9114958 (American), No. 9307710 (Massachusetts), No. 9217979 (Michigan), No. 9104975 (ODU) and No. 9118137 (U. Penn.); by the Schweizersche Nationalfonds (Basel); by the Commonwealth of Virginia (Virginia); by the Centre NAtional de la Recherche Scientifique and the Commissariat a l'Energie Atomique (French groups); and by the Japanese Ministry of Education, Science and Culture (Tohoku)

Efficacy of intervention strategies for bioremediation of crude oil in marine systems and effects on indigenous hydrocarbonoclastic bacteria

There is little information on how different strategies for the bioremediation of marine oil spills influence the key indigenous hydrocarbon-degrading bacteria (hydrocarbonoclastic bacteria, HCB), and hence their remediation efficacy. Therefore, we have used quantitative polymerase chain reaction to analyse changes in concentrations of HCB in response to intervention strategies applied to experimental microcosms. Biostimulation with nutrients (N and P) produced no measurable increase in either biodegradation or concentration of HCB within the first 5 days, but after 15 days there was a significant increase (29; P &lt; 0.05) in degradation of n-alkanes, and an increase of one order of magnitude in concentration of Thalassolituus (to 10 7 cells ml -1). Rhamnolipid bioemulsifier additions alone had little effect on biodegradation, but, in combination with nutrient additions, provoked a significant increase: 59 (P &lt; 0.05) more n-alkane degradation by 5 days than was achieved with nutrient additions alone. The very low Alcanivorax cell concentrations in the microcosms were hardly influenced by addition of nutrients or bioemulsifier, but strongly increased after their combined addition, reflecting the synergistic action of the two types of biostimulatory agents. Bioaugmentation with Thalassolituus positively influenced hydrocarbon degradation only during the initial 5 days and only of the n-alkane fraction. Bioaugmentation with Alcanivorax was clearly much more effective, resulting in 73 greater degradation of n-alkanes, 59 of branched alkanes, and 28 of polynuclear aromatic hydrocarbons, in the first 5 days than that obtained through nutrient addition alone (P &lt; 0.01). Enhanced degradation due to augmentation with Alcanivorax continued throughout the 30-day period of the experiment. In addition to providing insight into the factors limiting oil biodegradation over time, and the competition and synergism between HCB, these results add weight to the use of bioaugmentation in oil pollution mitigation strategies. © 2007 The Authors