title: Degradation of organic pollutants by methane grown microbial consortia.
abstract: Microbial consortia were enriched from various environmental samples with methane as the sole carbon and energy source. Selected consortia that showed a capacity for co-oxidation of naphthalene were screened for their ability to degrade methyl-tert-butyl-ether (MTBE), phthalic acid esters (PAE), benzene, xylene and toluene (BTX). MTBE was not removed within 24 h by any of the consortia examined. One consortium enriched from activated sludge ("AAE-A2"), degraded PAE, including (butyl-benzyl)phthalate (BBP), and di-(butyl)phthalate (DBP). PAE have not previously been described as substrates for methanotrophic consortia. The apparent Km and Vmax for DBP degradation by AAE-A2 at 20 degrees C was 3.1 +/- 1.2 mg l(-1) and 8.7 +/- 1.1 mg DBP (g protein x h)(-1), respectively. AAE-A2 also showed fast degradation of BTX (230 +/- 30 nmol benzene (mg protein x h)(-1) at 20 degrees C). Additionally, AAE-A2 degraded benzene continuously for 2 weeks. In contrast, a pure culture of the methanotroph Methylosinus trichosporium OB3b ceased benzene degradation after only 2 days. Experiments with methane mono-oxygenase inhibitors or competitive substrates suggested that BTX degradation was carried out by methane-oxidizing bacteria in the consortium, whereas the degradation of PAE was carried out by non-methanotrophic bacteria co-existing with methanotrophs. The composition of the consortium (AAE-A2) based on polar lipid fatty acid (PLFA) profiles showed dominance of type II methanotrophs (83-92% of biomass). Phylogeny based on a 16S-rRNA gene clone library revealed that the dominating methanotrophs belonged to Methylosinus/Methylocystis spp. and that members of at least 4 different non-methanotrophic genera were present (Pseudomonas, Flavobacterium, Janthinobacterium and Rubivivax).
authors.affiliation: Aalborg University, Department of Life Sciences, Section of Environmental Engineering, Aalborg, Denmark. mahe@bio.aau.dk
authors.forename: Martin
authors.initials: M
authors.lastname: Hesselsoe
authors.forename: Susanne
authors.initials: S
authors.lastname: Boysen
authors.forename: Niels
authors.initials: N
authors.lastname: Iversen
authors.forename: Lars
authors.initials: L
authors.lastname: Jørgensen
authors.forename: J Colin
authors.initials: JC
authors.lastname: Murrell
authors.forename: Ian
authors.initials: I
authors.lastname: McDonald
authors.forename: Stefan
authors.initials: S
authors.lastname: Radajewski
authors.forename: Helle
authors.initials: H
authors.lastname: Thestrup
authors.forename: Peter
authors.initials: P
authors.lastname: Roslev
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001555:Benzene Derivatives / Q000378:metabolism; D001673:Biodegradation, Environmental; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004783:Environmental Microbiology; D004785:Environmental Pollutants / Q000378:metabolism*; D005246:Feedback; D005798:Genes, Bacterial; D007700:Kinetics; D008697:Methane / Q000378:metabolism*; D008738:Methyl Ethers / Q000378:metabolism; D008969:Molecular Sequence Data; D009930:Organic Chemicals / Q000378:metabolism*; D010084:Oxidation-Reduction; D010795:Phthalic Acids / Q000378:metabolism; D010802:Phylogeny; D012722:Sewage / Q000382:microbiology; D013696:Temperature
chemical_list: D001555:Benzene Derivatives; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004785:Environmental Pollutants; D008738:Methyl Ethers; D009930:Organic Chemicals; D010795:Phthalic Acids; D012722:Sewage; C043243:methyl tert-butyl ether; D008697:Methane