DIBENZOTHIOPHENE BIODEGRADATION BY A PSEUDOMONAS SP IN POORLY DEGRADABLE ORGANIC-SOLVENTS

Selective aerobic biodesulphurization is possible using an unselective biocatalyst, such as a Pseudomonas sp. The results were obtained in a model solution dissolving an aromatic sulphur compound, such as diben zothiophene (DBT), in a poorly biodegradable solvent, such as dioctyl phthalate (DOG) or 2,2-4,4-6-8,8 heptamethylnonane (HMN). This system forces the microorganisms to work in 'obliged desulphurizing selectivi ty' (ODS) conditions, as indicated by the values of biodesulphurizatio n process selectivity which were 30-40% of effective organic phase bio desulphurization. ODS is a useful system for studying an ideal microbi al desulphurization process and its limiting factors with the aim of d eveloping a desulphurizing microorganism with high specificity The ODS process may also permit further work on the effects of different grou ps of compounds, such as n-alkanes and fatty acids which make up heavy oil, on the biodegradation rate of the aromatic sulphur compounds. Th e findings of this work show that diffusion, co-assimilation and micro bial hydrophobic effects may account for the inhibition effects of n-a lkanes and fatty acids on the biodegradation rare of DBT dissolved in DOC. Copyright (C) 1996 Elsevier Science Ltd