Registration Dossier

Environmental fate & pathways

Additional information on environmental fate and behaviour

Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Scientific publications which meets generally accepted standards

Data source

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Mycobacterium austroafricanum IFP 2173 was selected from among several strains as the best 2-EHN degrader. The 2-EHN biodegradation was investigated.
GLP compliance:
no

Results and discussion

Any other information on results incl. tables

Results of Nicolau et al. 2008

Carbon balance calculation, as well as organic-carbon measurement, indicated a release of metabolites in the culture medium. Further analysis by gas chromatography revealed that a single metabolite accumulated during growth. This metabolite had a molecular mass of 114 Da as determined by gas chromatography/mass spectrometry and was provisionally identified as 4-ethyldihydrofuran-2(3H)-one by liquid chromatography-tandem mass spectrometry analysis. Identification was confirmed by analysis of the chemically synthesized lactone. Based on these results, a plausible catabolic pathway is proposed whereby 2-EHN is converted to 4-ethyldihydrofuran-2(3H)-one, which cannot be metabolized further by strain IFP 2173. This putative pathway provides an explanation for the low energetic efficiency of 2-EHN degradation and its poor biodegradability.

Results of Nicolau et al. 2009

In a further publication using two-dimensional gel electrophoresis and a shotgun proteomic approach the proposed pathway involving an initial attack by an alkane hydroxylase and one turn of beta-oxidation, leading to the accumulation of a gamma-lactone as a dead-end product is discussed using the data on the induced enzymatic changes found.

Results of Solano-Serena et al. 2009

In aerobic liquid cultures, biodegradation of 2-EHN was assessed in biphasic liquid cultures using an inert non-aqueous phase liquid such as 2,2,4,4,6,8,8-heptamethylnonane (HMN) as solvent for the hydrophobic substrate. 2-EHN was found to be biodegradable by microbial communities from refinery wastewater treatment plants, but was recalcitrant to those of urban wastewater treatment facilities. In liquid cultures with HMN phase as non-aqueous phase liquid, some Mycobacterium austroafricanum strains were found to degrade and mineralize 2-EHN significantly.

Applicant's summary and conclusion