Draft genome sequence of the naphthalene degrader Herbaspirillum sp. strain RV1423

Herbaspirillum sp. strain RV1423 was isolated from a site contaminated with alkanes and aromatic compounds and harbors the complete pathway for naphthalene degradation. The new features found in RV1423 increase considerably the versatility and the catabolic potential of a genus of bacteria previously considered mainly to be diazotrophic endophytes to plants

A novel pathway for mineralization of the thiocarbamate herbicide molinate by a defined bacterial mixed culture

A bacterial mixed culture able to mineralize molinate as established, through enrichment, using mineral medium with molinate as the only carbon, nitrogen and energy source. The combination of five cultivable isolates, purified from the enrichment culture, permitted the reconstitution of a degrading consortium. Both enrichment and defined cultures were able to mineralize molinate without accumulation of degradation products by the end of the growth. Among the five isolates constituting the defined mixed culture, an actinomycete, strain ON4, was essential for biodegradation, being involved in the cleavage of the thioester bond of molinate, the initial step of the degradation pathway. Isolate ON4 was able to grow on molinate at concentrations below 2 mM, with the accumulation of ethanethiol and diethyl disulphide. These sulphur compounds were toxic to strain ON4 when accumulating at higher concentrations. However, this inhibitory effect was avoided by the presence of other members of the mixed culture, out of which isolates ON1 and ON2 were observed to consume ethanethiol and diethyl disulphide. In this way, interactions among defined mixed culture members involve metabolic and detoxifying associatio

Draft genome sequence of the naphthalene degrader Herbaspirillum sp. strain RV1423

Les élastomères thermoplastiques sont des matériaux relativement nouveaux qui se caractérisent à la fois par une mise en oeuvre rapide analogue à celle des polymères thermoplastiques et par des propriétés intermédiaires entre celles des élastomères vulcanisés et des polymères thermoplastiques plastifiés. On passe en revue de façon succincte les principaux élastomères thermoplastiques commerciaux ou en développement. Pour chacun d'eux, on décrit brièvement la structure, les propriétés, la mise en oeuvre et les applications. Thermoplastic elastomers are relatively new materials that are characterized both by rapid implementation, similar to that of thermoplastic polymers, and by properties intermediate between those of vulcanized elastomers and plasticized thermoplastic polymers. This article makes a succinct review of the leading commercial thermoplastic elastomers or the ones being developed. For each of them, a brief description is given of the structure, properties, implementation and applications

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

First draft genome sequence of the Acidovorax caeni sp. nov. type strain R-24608 (DSM 19327)

We report the draft genome sequence of the Acidovorax caeni type strain R-24608 that was isolated from activated sludge of an aerobic-anaerobic wastewater treatment plant. The closest strain to Acidovorax caeni strain R-24608 is Acidovorax sp. strain MR-S7 with a 55.4% (amino-acid sequence) open reading frames (ORFs) average similarity

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

Analysis of defence systems and a conjugative IncP-1 plasmid in the marine polyaromatic hydrocarbons-degrading bacterium Cycloclasticus sp. 78-ME

Marine prokaryotes have evolved a broad repertoire of defence systems to protect their genomes from lateral gene transfer including innate or acquired immune systems and infection-induced programmed cell suicide and dormancy. Here we report on the analysis of multiple defence systems present in the genome of the strain Cycloclasticus sp. 78-ME isolated from petroleum deposits of the tanker 'Amoco Milford Haven'. Cycloclasticus are ubiquitous bacteria globally important in polyaromatic hydrocarbons degradation in marine environments. Two 'defence islands' were identified in 78-ME genome: the first harbouring CRISPR-Cas with toxin-antitoxin system, while the second was composed by an array of genes for toxin-antitoxin and restriction-modification proteins. Among all identified spacers of CRISPR-Cas system only seven spacers match sequences of phages and plasmids. Furthermore, a conjugative plasmid p7ME01, which belongs to a new IncP-1θ ancestral archetype without any accessory mobile elements was found in 78-ME. Our results provide the context to the co-occurrence of diverse defence mechanisms in the genome of Cycloclasticus sp. 78-ME, which protect the genome of this highly specialized PAH-degrader. This study contributes to the further understanding of complex networks established in petroleum-based microbial communities

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