Aerobic biodegradation of alkylated aromatic hydrocarbons by a bacterial community

The aerobic degradation of aromatic compounds using a bacterial community from the Arcachon Harbour (South West coast of France) was studied. The aromatic fraction was prepared from an Arabian light crude oil residue and was incubated with this bacterial community under oxic conditions for up to 7 days. The study was focussed onto the degradation of alkylated naphthalenes, dibenzothiophenes and phenanthrenes present in the aromatic fraction. The disappearance of the various aromatic compounds was followed by gas chromatography/mass spectrometry. This bacterial community used the aromatic compounds as the sole source of carbon (more than 70% of the compounds disappeared within 7 days). The degradation phenomenon was shown to follow first order kinetics and did not show any difference between non-sulphur aromatic compounds (phenanthrenes) and sulphur aromatic compounds (dibenzothiophenes). The degradation of methylated phenanthrenes and dibenzothiophenes did not show significant differences in terms of isomeric composition. On the contrary, major differences in biodegradation rates have been observed for the dimethylated derivatives.