Selva Manikandan Athi Narayanan
Edinburgh Napier University, UK
Title: Biodesulphurisation of benzothiophene and dibenziothiophene by rhodococci isolated from oil contaminated soil
Biography
Biography: Selva Manikandan Athi Narayanan
Abstract
Biodesulphurisation (BDS) is an emerging technology that utilizes microorganisms for the removal of sulphur from fossil fuels. In this research, two rhodococci that were previously isolated from oil contaminated soils in Russia were found to possess robust desulphurisation activity against benzothiophene (BT) and dibenzothiophene (DBT) respectively. One strain was able to convert DBT to hydroxybiphenyl (2-HBP) with DBTO and DBTO2 as intermediates, whereas the other strain was able to convert BT into benzofuran, indicating that BDS reaction followed the well-known 4S pathway of desulphurisation. The species identity of the BT desulphurising strain and DBT desulphurising strain was confirmed as R. opacus and R. erythropolis respectively by 16S rRNA and gyrB gene sequence analysis and by whole genome sequence based OrthoANIu values (>95%). The DBT desulphurisation genes (dsz) of the R. erythropolis strain occurred as cluster sharing high similarity with the dsz operon of R. erythropolis IGTS8. The putative genes encoding the BT desulphurisation activity of the R. opacus strain was identified using comparative genomics. When cultured directly in a biphasic growth medium containing 10% model oil (hexadecane) or diesel containing 300 ppm sulphur, the R. erythropolis culture formed into an emulsion by interacting with the oil making it unsuitable for direct industrial application despite its desulphurisation potential. Whereas, the R. opacus culture formed distinct oil, biomass and aqueous phases which enabled easy extraction of the desulphurised oil with 80 fold reduced sulphur level, as measured by inductively coupled plasma - optical emission spectrometry (ICP-OES), making it a desirable strain for commercial application.