Regulation of catabolic pathways of phenoxyacetic acids and phenols in Alcaligenes eutrophus JMP 134

Alicaligenes eutrophus JMP 134 is able to grow on 2,4-dichloro-, 4-chloro-2-methyl- and 2-methylphenoxy acetic acid. The unsubstituted phenoxyacetic acid, however, is no growth substrate due to very poor induction of the 2,4-D monooxygenase. Spontaneous mutants of Alcaligenes eutrophus JMP 134 capable of growth with phenoxyacetic acid were selected on agar plates. One of these mutants, designated Alcaligenes eutrophus JMP 134-1, shows constitutive production of six enzymes of the 2,4-D pathway, which were known to be localized in at least three different transcriptional units. A common regulatory gene is postulated to be mutated. 2,4-Dichloro-, 4-chloro-2-methyl- and 2-methylphenoxyacetic acid were the inducers of the enzymes of the ldquochloroaromatic pathwayrdquo in Alcaligenes eutrophus JMP 134. Phenol and 2-methylphenol, metabolites of the degradation of phenoxyacetic acid and 2-methylphenoxyacetic acid, were shown to be inducers of the meta-cleavage pathway, whereas 2,4-dichlorophenol and 4-chloro-2-methylphenol were not. Thus efficient regulation prevents chloroaromatics from being misrouted into the unproductive meta-cleavage pathway. Because 2,4-dichloro-and 4-chloro-2-methylphenol did not show any induction potential, they were growth substrates only for the mutant strain JMP 134-1

(+)-4-Carboxymethyl-2,4-dimethylbut-2-en-4-olide as dead-end metabolite of 2,4-dimethylphenoxyacetic acid or 2,4-dimethylphenol by alcaligenes eutrophus JMP 134

2,4-Dimethylphenoxyacetic acid and 2,4-dimethylphenol are not growth substrates for Alcaligenes eutrophus JMP 134 although being cooxidized by 2,4-dichlorophenoxyacetate grown cells. None of the relevant catabolic pathways were induced by the dimethylphenoxyacetate, 3,5-Dimethylcatechol is not subject to metacleavage. The alternative ortho-eleavage is also unproductive and gives rise to (+)-4-carboxymethyl-2,4-dimethylbut-2-en-4-olide as a dead-end metabolite. High yields of this metabolite were obtained with the mutant Alcaligenes eutrophys JMP 134-1 which constitutively expresses the genes of 2,4-dichlorophenoxyacetic acid metabolism

Comparison of inoculums in the removal of 2-butoxyethanol from air emissions by biotrickling filter: Performance and microbial monitoring

2-butoxyethanol is one of the most used glycol ether in industrial activities and the treatment of air 2-butoxyethanol-emissions become necessary. Biotechnologies are potential treatment technologies due to their low operational costs. The use of two inoculums in the treatment of 2-butoxyethanol by biotrickling filters (BTFs) packed with polyurethane-foam was studied. A pure culture of Pseudomonas putida, previously adapted to 2-butoxyethanol, was used as inocula in a BTF operated in the University of Stuttgart. Fresh activated sludge from a municipal waste water treatment plant was used as inocula in a BTF operated in the University of Valencia. An empty bed residence time of 12.5 s and inlet concentrations of 400 and 800 mg/Nm3 were applied. After 40 days of operation at 400 mg/Nm3, the BTF inoculated with Pseudomonas putida reached removal efficiencies (REs) ∼ 80%, whereas the BTF inoculated with activated sludge presented REs ∼ 60%. At 800 mg/Nm3, the BTF inoculated with Pseudomonas putida reached REs ∼ 60%. Microbial community was monitored in both BTFs by using denaturing gradient gel electrophoresis analysis (DGGE) with subsequent 16S sequencing and plating methods using 2-butoxyethanol as sole carbon source

Metabolism of 2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid and 2-methylphenoxyacetic acid by Alcaligenes eutrophus JMP 134

Of eleven substituted phenoxyacetic acids tested, only three (2,4-dichloro-, 4-chloro-2-methyl- and 2-methylphenoxyacetic acid) served as growth substrates for Alcaligenes eutrophus JMP 134. Whereas only one enzyme seems to be responsible for the initial cleavage of the ether bond, there was evidence for the presence of three different phenol hydroxylases in this strain. 3,5-Dichlorocatechol and 5-chloro-3-methylcatechol, metabolites of the degradation of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid, respectively, were exclusively metabolized via the ortho-cleavage pathway. 2-Methylphenoxyacetic acid-grown cells showed simultaneous induction of meta- and ortho-cleavage enzymes. Two catechol 1,2-dioxygenases responsible for ortho-cleavage of the intermediate catechols were partially purified and characterized. One of these enzymes converted 3,5-dichlorocatechol considerably faster than catechol or 3-chlorocatechol. A new enzyme for the cycloisomerisation of muconates was found, which exhibited high activity against the ring-cleavage products of 3,5-dichlorocatechol and 4-chlorocatechol, but low activities against 2-chloromuconate and muconate

Enrichment of dibenzofuran utilizing bacteria with high co-metabolic potential towards dibenzodioxin and other anellated aromatics

Dibenzofuran degrading bacteria were enriched from various environmental sources. A mutualistic mixed culture of strain DPO 220 and strain DPO 230 was characterized. Strain DPO 220 alone showed limited growth with dibenzofuran as sole source of carbon and energy (td ≥ 4.5 h). A labile degradation product, C12H10O5, and salicylate were isolated from the culture fluid. Salicylate was found to be a central intermediate of DBF-degradation.Strain DPO 220 co-metabolized a wide range of anellated aromatics as well as heteroaromatics. High rates of co-oxidation of dibenzodioxin demonstrate analogue-enrichment to be a powerful technique for selecting enzymatic activities for otherwise non-degradable substrates

Simultaneous degradation of chloro- and methylaromatics via ortho pathway by genetically engineered bacteria and natural soil isolates

The simultaneous bacterial metabolism of chloro- and methylaromatics via ortho- or metapathway, normally results in incomplete degradation and death of the organisms. This is caused by misrouting of central intermediates. i.e. substituted catechols into unproductive pathways and suicide inactivation of the key enzyme of meta pathway, (catechol 2,3-dioxygenase). The meta pathway proved to be definitely unsuited for productive metabolism of chloroaromatics. Therefore two strategies were used for simultaneous degradation of mixtures of chloro- and methylaromatics via ortho pathways: Methyllactons or certain mixtures of chloro- and methylaromatics were used as enrichment substrates, yielding strains which metabolized these compounds almost exclusively via the desired pathway. Alternatively relevant enzymes from five different catabolic pathways of three distinct soil bacteria were combined in a patchwork fashion generating a functional ortho cleavage route for methylaromatics coexisting with the ortho cleavage pathway of chloroaromatics

Assemblage of ortho cleavage route for simultaneous degradation of chloro- and methylaromatics

Genetic engineering is a powerful means of accelerating the evolution of new biological activities and has considerable potential for constructing microorganisms that can degrade environmental pollutants. Critical enzymes from five different catabolic pathways of three distinct soil bacteria have been combined in patchwork fashion into a functional ortho cleavage route for the degradation of methylphenols and methylbenzoates. The new bacterium thereby evolved was able to degrade and grow on mixtures of chloro- and methylaromatics that were toxic even for the bacteria that could degrade the individual components of the mixtures. Except for one enzymatic step, the pathway was fully regulated and its component enzymes were only synthesized in response to the presence of pathway substrates

The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Degradation of Alkyl Methyl Ketones by Pseudomonas veronii MEK700▿

Pseudomonas veronii MEK700 was isolated from a biotrickling filter cleaning 2-butanone-loaded waste air. The strain is able to grow on 2-butanone and 2-hexanol. The genes for degradation of short chain alkyl methyl ketones were identified by transposon mutagenesis using a newly designed transposon, mini-Tn5495, and cloned in Escherichia coli. DNA sequence analysis of a 15-kb fragment revealed three genes involved in methyl ketone degradation. The deduced amino acid sequence of the first gene, mekA, had high similarity to Baeyer-Villiger monooxygenases; the protein of the second gene, mekB, had similarity to homoserine acetyltransferases; the third gene, mekR, encoded a putative transcriptional activator of the AraC/XylS family. The three genes were located between two gene groups: one comprising a putative phosphoenolpyruvate synthase and glycogen synthase, and the other eight genes for the subunits of an ATPase. Inactivation of mekA and mekB by insertion of the mini-transposon abolished growth of P. veronii MEK700 on 2-butanone and 2-hexanol. The involvement of mekR in methyl ketone degradation was observed by heterologous expression of mekA and mekB in Pseudomonas putida. A fragment containing mekA and mekB on a plasmid was not sufficient to allow P. putida KT2440 to grow on 2-butanone. Not until all three genes were assembled in the recombinant P. putida was it able to use 2-butanone as carbon source. The Baeyer-Villiger monooxygenase activity of MekA was clearly demonstrated by incubating a mekB transposon insertion mutant of P. veronii with 2-butanone. Hereby, ethyl acetate was accumulated. To our knowledge, this is the first time that ethyl acetate by gas chromatographic analysis has been definitely demonstrated to be an intermediate of MEK degradation. The mekB-encoded protein was heterologously expressed in E. coli and purified by immobilized metal affinity chromatography. The protein exhibited high esterase activity towards short chain esters like ethyl acetate and 4-nitrophenyl acetate