Search results for "DEGRADATION"

Unraveling metabolic flexibility of rhodococci in PCB transformation

2021

International audience; Even though the genetic attributes suggest presence of multiple degradation pathways, most of rhodococci are known to transform PCBs only via regular biphenyl (bph) pathway. Using GC-MS analysis, we monitored products formed during transformation of 2,4,4′-trichlorobiphenyl (PCB-28), 2,2′,5,5′-tetrachlorobiphenyl (PCB-52) and 2,4,3′-trichlorobiphenyl (PCB-25) by previously characterized PCB-degrading rhodococci Z6, T6, R2, and Z57, with the aim to explore their metabolic pleiotropy in PCB transformations. A striking number of different transformation products (TPs) carrying a phenyl ring as a substituent, both those generated as a part of the bph pathway and an array…

Bacterial community analysis of a gas-phase biotrickling filter for biogas mimics desulfurization through the rRNA approach

2010

Abstract The bacterial composition of a lab-scale biotrickling filter (BTF) treating high loads of H 2 S was investigated by the rRNA approach. Two 16S rRNA gene clone libraries were established 42 and 189 d after reactor startup, while fluorescent in-situ hybridization (FISH) with DNA probes was performed throughout 260 d of reactor operation. Diversity, community structure and metamorphosis were studied from reactor startup to fully-established pseudo-steady state operation at near neutral pH and at an inlet H 2 S concentration of 2000 ppmv (load of 55.6 g H 2 S m −3  h −1 ). In addition, FISH was used for assessing the spatial distribution of sulfur-oxidizing bacteria (SOB) along the len…

Trimeprazine is enantioselectively degraded by an activated sludge in ready biodegradability test conditions

2018

[EN] A great number of available pharmaceuticals are chiral compounds. Although they are usually manufactured as racemic mixtures, they can be enantioselectively biodegraded as a result of microbial processes. In this paper, a biodegradability assay in similar conditions to those recommended in OECD tests of enantiomers of trimeprazine (a phenothiazine employed as a racemate) is carried out. Experiments were performed in batch mode using a minimal salts medium inoculated with an activated sludge (collected from a Valencian Waste Water Treatment Plant, WWTP) and supplemented with the racemate. The concentration of the enantiomers of trimeprazine were monitored by means of a chiral HPLC metho…

Simulated solar UV-irradiation of endocrine disrupting chemical octylphenol.

2009

The photolysis of octylphenol (OP) was investigated using a solar simulator in the absence/presence of dissolved natural organic matter (DNOM), HCO(3)(-), NO(3)(-) and Fe(III) ions. The effects of different parameters such as initial pH, initial concentration of substrate, temperature, and the effect of hydrogen peroxide concentration on photodegradation of octylphenol in aqueous solution have been assessed. The results indicate that the oxidation rate increases in the presence of H(2)O(2), nitrate and DNOM. Phenol, 1,4-dihydroxylbenzene and 1,4-benzoquinone were identified as intermediate products of photodegradation of octylphenol, through an HPLC method. In addition, the disappearance of…

Characterization of an isoproturon mineralizing bacterial culture enriched from a French agricultural soil.

2009

The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized by a bacterial culture isolated from an agricultural soil regularly exposed to IPU. Molecular analysis of the bacterial culture by DNA fingerprinting, cloning and sequencing of the 16S rRNA genes revealed that it consisted of six different members among whom the dominant was related to Sphingomonas sp. Six bacterial strains belonging to genera Ancylobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Variovorax and Agrobacterium were isolated from the IPU-degrading culture. None of these were able to degrade IPU in pure culture and only the intact culture sustained th…

Degradation of long-chain n-alkanes in soil microcosms by two actinobacteria

2012

The ability of two recently isolated actinobacteria, that degrade medium and long chain n-alkanes in laboratory water medium, was investigated in soil microcosms using different standard soils that were artificially contaminated with n-alkanes of different length (C(12)- C(20)- C(24)- C(30)). The two strains, identified as Nocardia sp. SoB and Gordonia sp. SoCp, revealed a similar high HC degradation efficiency with an average of 75% alkane degraded after 28 days incubation. A selectivity of bacteria towards n-alkanes of different length was detected as well as a consistent effect of soil texture and other soil physical chemical characteristics on degradation. It was demonstrated the specif…

RISK OF EXPOSURE TO ASBESTOS IN CASE OF THE MECHANICAL DEGRADATION OF SOME ASBOCEMENT COMPOSITES

2011

Occurrence of antibiotics in the aquatic environment

1999

The recent monitoring of drug residues in the aquatic environment has gained much interest as many pharmaceutical compounds can frequently be found in sewage treatment plant (STP) effluents and river water at concentrations up to several microgram/l. This article describes the analysis of various water samples for 18 antibiotic substances, from the classes of macrolid antibiotics, sulfonamides, penicillins and tetracyclines. Samples were preconcentrated via lyophilization and quantified using HPLC-electrospray-tandem-mass spectrometry. The investigated STP effluents and surface water samples showed frequent appearance of an erythromycin degradation product, roxithromycin and sulfamethoxazol…

Iron-based metal-organic framework: Synthesis, structure and current technologies for water reclamation with deep insight into framework integrity.

2021

Water is a supreme requirement for the existence of life, the contamination from the point and non-point sources are creating a great threat to the water ecosystem. Advance tools and techniques are required to restore the water quality and metal-organic framework (MOFs) with a tunable porous structure, striking physical and chemical properties are an excellent candidate for it. Fe-based MOFs, which developed rapidly in recent years, are foreseen as most promising to overcome the disadvantages of traditional water depolluting practices. Fe-MOFs with low toxicity and preferable stability possess excellent performance potential for almost all water remedying techniques in contrast to other MOF…

Co-digestion of sewage sludge and sterilized solid slaughterhouse waste: Methane production efficiency and process limitations

2012

The rendering product of Category 2 and 3 Animal By-Products is known as sterilized mass (SM) and it is mainly composed of fat and proteins, making it interesting substrate for anaerobic digestion. Batch and semi-continuous laboratory experiments were carried out to investigate the effect of SM addition in co-digestion with sewage sludge on methane production and possible process limitations. Results showed that SM addition in the feed mixture up to 5% (w/w), corresponding to 68.1% of the organic loading, increased methane production 5.7 times, without any indication of process inhibition. Further increase of SM addition at 7.5% (w/w) caused methane production decrease and volatile solids r…