Optimization of nicotinamide and riboflavin in the biodesulfurization of dibenzothiophene using response surface methodology

Dibenzothiophene (DBT) is a sulfuric compound and resistant to Hydrodesulfurization process. Rhodococcuserythropolis R1، a previously isolated bacterial strain، is capable to bioconversion of DBT to 2-hydroxybiphenyl (2-HBP). Materials and method s: The effect of nicotinamide (precursor of NAD) and riboflavin (precursor of FMN) on DBT biodesulfurization and growth rate by this strain was studied using Gibbs assay and turbidimeteric assay respectively. The level of cofactor precursors were optimized using response surface methodology (RSM). Analyses showed that both nicotinamide and riboflavin were statistically significant and could enhance the biodesulfurization rate of DBT by induction of dsz operon. The optimum level of nicotinamide and riboflavin was obtained at 10. 67 mM and 34. 2 µM respectively. Discussion and In spite of increasing in BDS، the addition of these cofactor precursors led to decreased growth rate and biomass production due to limitated effect of produced 2-HBP.