Two-stage process design for the biodesulphurisation of a model diesel by a newly isolated Rhodococcus globerulus DAQ3

New bacteria were enriched and isolated from oil-contaminated soils and desulphurisation activity was compared with reported bacterial strains. Of the six different bacterial strains, a newly isolated Rhodococcus globerulus DAQ3 showed the highest activity and stability for desulphurisation of dibenzothiophene (DBT) in a two-phase system. The overall average production rate of 2-hydroxybiphenyl was 18 μmol/g DCW/h during 9 h, which was over two-fold higher than the reference strain Rhodococcus erythropolis IGTS8. Based on the activity analysis, metabolite inhibition in the aqueous phase was proven, then a two-stage bioprocess was developed for the desulphurisation of a model diesel, and as a result, the new strain DAQ3 reduced the total sulphur in the model diesel by 33%, with DBT conversion of 65%, within 48 h.