Using laboratory and field experiments, the ability of Streptomyces aureus HP-S-01 to eliminate β-cypermethrin (β-CP) and its metabolite 3-phenoxybenzaldehyde (3-PBA) in soils was investigated. In the laboratory, 80.5% and 73.1% of the initial dose of β-CP and 3-PBA (50 mg kg(-1)) was removed in sterilized soils within 10 days, respectively, while in the same period, disappearance rate of β-CP and 3-PBA in non-sterilized soils was higher and reached 87.8% and 79.3%, respectively. Furthermore, the disappearance process followed the first-order kinetics and the half-life (T (1/2)) for β-CP and 3-PBA reduced by 20.3-52.9 and 133.7-186.8 days, respectively, as compared to the controls. The addition of sucrose to the soils enhanced the ability of strain HP-S-01 to eliminate β-CP and 3-PBA. Similar results were observed in the field experiments. The introduced strain HP-S-01 quickly adapted to the environment and rapidly removed β-CP and 3-PBA without any lag phases in the field experiments. Compared with the controls, 47.9% and 67.0% of applied dose of β-CP and 3-PBA was removed from the soils without extra carbon sources and 52.5% and 73.3% of β-CP and 3-PBA was eliminated in soils supplemented with sucrose within 10 days, respectively. Analysis of β-CP degradation products in soil indicated that the tested strain transform β-CP to 3-PBA and α-hydroxy-3-phenoxy-benzeneacetonitrile. However, both intermediates were transient and they disappeared after 10 days. Therefore, the selected actinomyces strain HP-S-01 is suitable for the efficient and rapid bioremediation of β-CP contaminated soils.
Continuous use of the pyrethroid insecticide beta-cypermethrin (beta-cp) has resulted in serious environmental contamination problems. We report here that a novel bacterial strain BSF01, which was isolated from activated sludge and identified as Bacillus subtilis (collection number: CCTCC AB 2014103), showed high efficiency in degrading beta-cp. Strain BSF01 was able to utilize beta-cp as the sole carbon source for growth and degraded 89.4 % of 50 mg L(-1) beta-cp within 7 days. The optimal conditions for beta-cp degradation were determined to be 34.5 °C, pH 6.7, and inocula amount 0.11 g dry wt L(-1) using response surface methodology. The kinetic parameters q max, K s, and K i were established to be 2.19 day(-1), 76.37 mg L(-1), and 54.14 mg L(-1), respectively. The critical inhibitor concentration was determined to be 64.30 mg L(-1). Seven metabolites were identified by gas chromatography-mass spectrometry. Furthermore, a novel biodegradation pathway for beta-cp was proposed on the basis of analysis of the metabolites. This strain was also capable of degrading a wide range of pyrethroid insecticides including cypermethrin, deltamethrin, cyhalothrin, and beta-cyfluthrin, which similar to beta-cp are hazardous chemicals. Taken together, our results depict the biodegradation pathway of beta-cp and highlight the promising potentials of strain BSF01 in bioremediation of pyrethroid-contaminated environments.
Inspired by the recent measurement of the ratio of B c branching fractions to J/ψπ + and J/ψμ + ν μ final states at the LHCb detector, we study the semileptonic decays of B c meson to the S-wave ground and radially excited 2S and 3S charmonium states with the perturbative QCD approach. After evaluating the form factors for the transitions B c → P, V , where P and V denote pseudoscalar and vector S-wave charmonia, respectively, we calculate the branching ratios for all these semileptonic decays. The theoretical uncertainty of hadronic input parameters are reduced by utilizing the light-cone wave function for the B c meson. It is found that the predicted branching ratios range from 10 −7 up to 10 −2 and could be measured by the future LHCb experiment. Our prediction for the ratio of branching fractionsis in good agreement with the data. For B c → V lν l decays, the relative contributions of the longitudinal and transverse polarization are discussed in different momentum transfer squared regions. These predictions will be tested on the ongoing and forthcoming experiments.
3-Phenoxybenzoic acid (3-PBA) is of great environmental concern with regards to endocrine disrupting activity and widespread occurrence in water and soil, yet little is known about microbial degradation in contaminated regions. We report here that a new bacterial strain isolated from soil, designated DG-02, was shown to degrade 95.6% of 50 mg·L−1 3-PBA within 72 h in mineral salt medium (MSM). Strain DG-02 was identified as Bacillus sp. based on the morphology, physio-biochemical tests and 16S rRNA sequence. The optimum conditions for 3-PBA degradation were determined to be 30.9°C and pH 7.7 using response surface methodology (RSM). The isolate converted 3-PBA to produce 3-(2-methoxyphenoxy) benzoic acid, protocatechuate, phenol, and 3,4-dihydroxy phenol, and subsequently transformed these compounds with a q max, K s and K i of 0.8615 h−1, 626.7842 mg·L−1 and 6.7586 mg·L−1, respectively. A novel microbial metabolic pathway for 3-PBA was proposed on the basis of these metabolites. Inoculation of strain DG-02 resulted in a higher degradation rate on 3-PBA than that observed in the non-inoculated soil. Moreover, the degradation process followed the first-order kinetics, and the half-life (t 1/2) for 3-PBA was greatly reduced as compared to the non-inoculated control. This study highlights an important potential application of strain DG-02 for the in situ bioremediation of 3-PBA contaminated environments.
The spectrum of charged particles hopping on a kagomé lattice in a uniform transverse magnetic field shows an unusual set of Landau levels at low field. They are unusual in two respects: the lowest Landau levels are paramagnetic so their energies decrease linearly with increasing field magnitude, and the spacings between the levels are not equal. These features are shown to follow from the degeneracy of the energy bands in zero magnetic field. We give a general discussion of Landau levels in the case of two degenerate bands, and show how the kagomé lattice tight-binding model includes one special case of this more general problem. We also discuss the consequences of this for the behavior of the critical temperature of a kagomé grid superconducting wire network, which is the experimental system that originally motivated this work.Typeset using REVT E X 1
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