Mikrobieller Abbau von 14C-markiertem Pyren und Benzo[a]pyren durch eine erstmals beschriebene Mycobacterium-Spezies

Pyrene and benzo[a]pyrene belonging to the class of polycyclic aromatic hydrocarbons (PAHs) are of concern for both human health and the environment due to their mutagenicity, carcinogenicity and persistence. The present thesis deals with the microbial degradation of pyrene and benzo[a]pyrene by bacterial pure cultures. A total of 104 different microbial strains were isolated from a PAH-degrading bacterial mixed culture, but only 12 strains turned out to be PAH-degraders. The most effective strains 17A3 and 4IIb were chosen, characterized and used in degradation experiments. The pure culture of 17A3 was identified as a new member of the genus Mycobacterium which was not described before. In order to compare strain 17A3 to strain 4IIb on the DNA level, 16S-23S-rDNA-Intergenic-Spacer-Amplification (RISA) was conducted indicating that both strains are belonging to the same species. Degradation experiments were carried out with both non-labelled and radiolabelled pyrene and benzo[a]pyrene, respectively in order to quantify reliably the degradation and to detect radiolabelled metabolites. Strains 17A3 and 4IIb were able to use pyrene as sole source of carbon and energy and converted pyrene completely into carbon dioxide, metabolites and biomass. Metabolites detected in the culture medium were identified as far as possible by means of radio-TLC, HPLC and GC-MS analysis and correspond to the degradation pathways described in the literature. Dimethoxy-pyrene was identified as an additional metabolite formed from pyrene. In contrast, both strains cannot use benzo[a]pyrene for growth. Degradation studies of benzo[a]pyrene were therefore carried out in presence of pyrene. Benzo[a]pyrene was mineralized at this cometabolic conditions only to a minor extent (up to 2% of applied benzo[a]pyrene). Nevertheless, it was demonstrated that strain 17A3 was able to convert benzo[a]pyrene almost completely into more polar metabolites. Due to the special 12C:14C isotope ratio of the applied radiolabelled benzo[a]pyrene, metabolites can be differed from matrix substances and can be attributed reliably to the parent compound. Metabolites were identified as far as possible by the mass spectra indicating two different benzo[a]pyrene-dihydrodiols and two ring fission products like chrysene-dicarboxylic acid and hydroxy-methoxy-chrysene. The degradation of pyrene and benzo[a]pyrene in a mixture was influenced reciprocally by each other: Mineralisation of benzo[a]pyrene ceased if pyrene was depleted and increased if pyrene was added. The degradation rate of benzo[a]pyrene cannot be increased with increasing benzo[a]pyrene concentration. Furthermore, the degradation rates of pyrene decreased if benzo[a]pyrene was present. A toxic effect of benzo[a]pyrene on the degrading microorganisms could not be shown. However, it could not be excluded by means of the performed experiments.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Derz, Kerstin

Contributors dc:contributor

• Schuphan, Ingolf

• info:eu-repo/classification/ddc/570
• Pyren
• Benzopyren
• Mikrobieller Abbau
• Mycobacterium
• Chromatographie
• Kopplung <Analytische Chemie>
• Markierte Verbindungen
• Biowissenschaften, Biologie
• PAK
• Benzo[a]pyren

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123669%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62073