Biodesulphurization Potentials of Microorganisms isolated from Coal, spent Refinery Catalyst and Hydrocarbon-contaminated Soil and Water Samples in a Tropical Ecosystem

Abstract

The biodesulphurization (BDS) potentials of bacteria and yeasts isolated by enrichment in sulfur-free mineral salts medium (SFMSM) supplemented with 0.2 mM dibenzothiophene (DBT) from different samples in Nigeria were investigated. The rate of growth on DBT and conversion of the sulfite released from DBT to sulfate for growth was determined by measuring the optical density at 600 nm (OD₆₀₀) and 420 nm (OD₄₂₀) respectively, and the concentration of residual DBT in the culture medium after 72hrs determined by HPLC. All the isolates showed no appreciable increase in OD₆₀₀ within the first 6 hrs; Corynebacterium jeikeium EMB112 and EMB111 have the highest and lowest OD₆₀₀ of 1.3 and 0.39 respectively. Except for C. jeikeium EMB112 and Candida valida EMB911, sulfate production peaked at 72 hrs for all the isolates. However, there was a slight increase in sulfate concentration form 72 hrs (1.03 mM) to 144 hrs (1.08 mM) for strain EMB 112 while there is no change within the same time period for strain EMB911.  Rate of DBT utilization (mM/day) ranged between 0.1035 (82.2%) and 0.1259 (100%). The utilization of DBT as a growth substrate by the organisms of the present study showed that they are potential candidates for BDS applications.