NULLAbstract
Aims: The major aims of this study are to determine the capability of sulphur
oxidizing bacterium (SOB-1) to desulphurize dibenzothiophene (DBT) and
crude oil, detection of the reaction kinetics and identify the proposed pathway
of DBT desulphurization.
Methods and Results: The isolate was genetically identified based on 16S
rRNA gene sequencing as Klebsiella oxytoca and deposited in the Genebank
database under the accession number: MT355440. The HPLC analysis of the
remaining DBT concentration revealed that, SOB-1 could desulphurize 90% of
DBT (0
25 mmol l−1) within 96 h. The maximum production of sulphate ions
from the desulphurization of DBT (0
36 mmol l−1) and crude oil
(0
4 mmol l−1) could be quantitatively detected after 48 h of incubation at
30°C. The high values of correlation coefficient (R2) obtained at all studied
concentrations; suggested that biodesulfurization kinetics of DBT follows the
first-order reaction model. The kinetics studies showed that, DBT may have an
inhibitory effect on SOB-1 when the initial concentration exceeded
0
75 mmol l−1. The GC-MS analysis exhibited four main metabolites rather
than DBT. The most important ones are 2-hydroxybiphenyl (2-HBP) and
methoxybiphenyl n(2-MBP).
Conclusions: Klebsiella oxytoca SOB-1 catalyzes the desulphurization of DBT
through 4S pathway and forms four main metabolic products. The release of
sulphate ion and formation of 2-HBP indicating the elimination of sulphur
group without altering the carbon skeleton of DBT. The bacterial strain could also catalyzes desulphurization of crude oil. The desulphurization kinetics follows the first-order reaction model.
Significance and Impact of the Study: Klebsiella oxytoca SOB-1 could be used as a promising industrial and environmental biodesulfurizing agent as it is not affecting carbon skeleton of thiophenic compounds and forming less toxic metabolic product (2-MBP).