Draft genome sequence of [i]Pseudomonas[/i] sp. strain ADP, a bacterial model for studying the degradation of the herbicide atrazine

EAPôle BIOME & IPMWe report here the 7,259,392-bp draft genome of [i]Pseudomonas[/i] sp. strain ADP. This is a bacterial strain that was first isolated in the 1990s from soil for its ability to mineralize the herbicide atrazine. It has extensively been studied as a model to understand the atrazine biodegradation pathway. This genome will be used as a reference and compared to evolved populations obtained by experimental evolution conducted on this strain under atrazine selection pressure. Copyright 2016 Devers-Lamrani et al

Terahertz-bandwidth coherence measurements of a quantum dash laser in passive and active mode-locking operation

International audienceThis research carries out coherence measurements of a 42.7GHz quantum dash (QDash) semiconductor laser when passively, electrically and optically mode-locked. Coherence of the spectral lines from the mode-locked laser is determined by examining the radio frequency (RF) beat-tone linewidth as the mode spacing is increased up to 1.1THz. Electric field measurement of the QDash laser are also presented, from which a comparison between experimental results and accepted theory for coherence in passively mode-locked lasers has been performed

A spectrograph instrument concept for the Prime Focus Spectrograph (PFS) on Subaru Telescope

We describe the conceptual design of the spectrograph opto-mechanical concept for the SuMIRe Prime Focus Spectrograph (PFS) being developed for the SUBARU telescope. The SuMIRe PFS will consist of four identical spectrographs, each receiving 600 fibers from a 2400 fiber robotic positioner at the prime focus. Each spectrograph will have three channels covering in total, a wavelength range from 380 nm to 1300 nm. The requirements for the instrument are summarized in Section 1. We present the optical design and the optical performance and analysis in Section 2. Section 3 introduces the mechanical design, its requirements and the proposed concepts. Finally, the AIT phases for the Spectrograph System are described in Section 5.Comment: 8 pages, 5 figures, submitted to "Ground-based and Airborne Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki Takami, Editors, Proc. SPIE 8446 (2012)

Betaproteobacteria dominance and diversity shifts in the bacterial community of a PAH-contaminated soil exposed to phenanthrene.

International audienceIn this study, the PAH-degrading bacteria of a constructed wetland collecting road runoff has been studied through DNA stable isotope probing. Microcosms were spiked with (13)C-phenanthrene at 34 or 337 ppm, and bacterial diversity was monitored over a 14-day period. At 337 ppm, PAH degraders became dominated after 5 days by Betaproteobacteria, including novel Acidovorax, Rhodoferax and Hydrogenophaga members, and unknown bacteria related to Rhodocyclaceae. The prevalence of Betaproteobacteria was further demonstrated by phylum-specific quantitative PCR, and was correlated with a burst of phenanthrene mineralization. Striking shifts in the population of degraders were observed after most of the phenanthrene had been removed. Soil exposed to 34 ppm phenanthrene showed a similar population of degraders, albeit only after 14 days. Results demonstrate that specific Betaproteobacteria are involved in the main response to soil PAH contamination, and illustrate the potential of SIP approaches to investigate PAH biodegradation in soil

Development of a MSW gasification model for flexible integration into a MFA-LCA framework

This paper presents the development of a comprehensive gasification module designed to be integrated in a MFA-LCA framework. From existing gasification models present in the literature, the most appropriate modelling strategy is selected and implemented into the module. This module needs to be able to capture the influence of input parameters, such as gasification reactor type, oxidizing agent, feedstock composition and operating conditions on the process outputs, including syngas yield, its composition and LHV, as well as tar and char contents. A typical gasification process is usually modelled in four steps: drying, pyrolysis, oxidation and reduction. Models representing each of these steps are presented in this paper. Since the type of gasification reactor is taken into account in the module, models for downdraft moving bed and bubbling fluidized bed reactor are also reviewed. The gasification module will be integrated into a MFA framework (VMR-Sys), which enables calculation of relevant gasifier feedstock parameters, such as moisture content, composition, properties and particle size distribution. Outputs from the module will also include elemental compositions obtained from VMR-Sys calculations. Finally, all outputs from the module will be used to build LCA-inventory data

Categorizing chlordecone potential degradation products to explore their environmental fate

EA BIOmE SUPDAT INRAInternational audienceChlordecone (C10Cl10O; CAS number 143-50-0) has been used extensively as an organochlorine insecticide but is nowadays banned and listed on annex A in The Stockholm Convention on Persistent Organic Pollutants (POPs). Although experimental evidences of biodegradation of this compound are scarce, several dechlorination products have been proposed by Dolfing et al. (2012) using Gibbs free energy calculations to explore different potential transformation routes. We here present the results of an in silico classification (TyPol - Typology of Pollutants) of chlordecone transformation products (TPs) based on statistical analyses combining several environmental endpoints and structural molecular descriptors. Starting from the list of putative chlordecone TPs and considering available data on degradation routes of other organochlorine compounds, we used different clustering strategies to explore the potential environmental behaviour of putative chlordecone TPs from the knowledge on their molecular descriptors. The method offers the possibility to focus on TPs present in different classes and to infer their environmental fate. Thus, we have deduced some hypothetical trends for the environmental behaviour of TPs of chlordecone assuming that TPs, which were clustered away from chlordecone, would have different environmental fate and ecotoxicological impact compared to chlordecone. Our findings suggest that mono- and di-hydrochlordecone, which are TPs of chlordecone often found in contaminated soils, may have similar environmental behaviour in terms of persistence

Ecotoxicological Impact of the Bioherbicide Leptospermone on the Microbial Community of Two Arable Soils

EA BIOmEInternational audienceThe ecotoxicological impact of leptospermone, a β-triketone bioherbicide, on the bacterial community of two arable soils was investigated. Soil microcosms were exposed to 0× (control), 1× or 10× recommended dose of leptospermone. The β-triketone was moderately adsorbed to both soils (i.e.,: K fa ∼ 1.2 and K −1 oc ∼ 140 mL g). Its dissipation was lower in sterilized than in unsterilized soils suggesting that it was mainly influenced by biotic factors. Within 45 days, leptospermone disappeared almost entirely from one of the two soils (i.e., DT 50 < 10 days), while 25% remained in the other. The composition of the microbial community assessed by qPCR targeting 11 microbial groups was found to be significantly modified in soil microcosms exposed to leptospermone. Pyrosequencing of 16S rRNA gene amplicons showed a shift in the bacterial community structure and a significant impact of leptospermone on the diversity of the soil bacterial community. Changes in the composition, and in the α-and β-diversity of microbial community were transient in the soil able to fully dissipate the leptospermone, but were persistent in the soil where β-triketone remained. To conclude the bacterial community of the two soils was sensitive to leptospermone and its resilience was observed only when leptospermone was fully dissipated

Isolation and characterization of Bradyrhizobium sp. SR1 degrading two β-triketone herbicides

In this study, a bacterial strain able to use sulcotrione,a β-triketone herbicide, as sole source of carbon and energy was isolated from soil samples previously treated with this herbicide. Phylogenetic study based on16S rRNA gene sequence showed that the isolate has 100 % of similarity with several Bradyrhizobium and was accordingly designated as Bradyrhizobium sp. SR1. Plasmid profiling revealed the presence of a large plasmid (>50 kb) in SR1 not cured under nonselective conditions. Its transfer to Escherichia coli by electroporation failed to induce β-triketone degrading capacity,suggesting that degrading genes possibly located on this plasmid cannot be expressed in E. coli or that they are not plasmid borne. The evaluation of the SR1 ability to degrade various synthetic (mesotrione and tembotrione) and natural (leptospermone) triketones showed that this strain was also able to degrademesotrione. Although SR1 was able to entirely dissipate both herbicides, degradation rate of sulcotrione was ten times higher than that of mesotrione, showing a greater affinity of degrading-enzyme system to sulcotrione. Degradation pathway of sulcotrione involved the formation of 2-chloro-4-mesylbenzoic acid (CMBA), previously identified in sulcotrione degradation, and of a new metabolite identified as hydroxy-sulcotrione.Mesotrione degradation pathway leads to the accumulation of-methylsulfonyl-2-nitrobenzoic acid(MNBA) and 2-amino-4 methylsulfonylbenzoic acid(AMBA), two well-known metabolites of this herbicide. Along with the dissipation of β-triketones, one could observe the decrease in 4-hydroxyphenylpyruvate dioxygenase(HPPD) inhibition, indicating that toxicity was due to parent molecules, and not to the formed metabolites. This is the first report of the isolation of bacterial strain able to transform two β-triketones