Jerusalem artichoke as low-cost fructose-rich feedstock for fossil fuels desulphurization by a fructophilic bacterium.

Abstract

Through biodesulphurization (BDS) is possible to remove the sulphur present in fossil fuels to carry out the very strict legislation. However, this biological process is limited by the cost of the culture medium, and thus, it is important to explore cheaper alternative carbon sources, such as Jerusalem artichoke (JA). These carbon sources usually contain sulphates which interfere with the BDS process. The goal of this work was to remove the sulphates from Jerusalem artichoke juice (JAJ) through BaCl2 precipitation viewing the optimization of dibenzothiophene (DBT) desulphurization by Gordonia alkanivorans strain 1B. Using a statistical design (Doehlert distribution), the effect of BaCl2 concentration (0.125-0.625%) and pH (5-9) was studied on sulphate concentration in hydrolysed JAJ. A validated surface response derived from data indicated that zero sulphates can be achieved with 0.5-0.55% (w/v) BaCl2 at pH 7; however, parallel BDS assays showed that the highest desulphurization was obtained with the juice treated with 0.5% (w/v) BaCl2 at pH 8.73. Further assays demonstrated that enhanced DBT desulphurization was achieved using hydrolysed JAJ treated in these optimal conditions. A total conversion of 400 μmol l(-1) DBT into 2-hydroxybiphenyl (2-HBP) in <90 h was observed, attaining a 2-HBP maximum production rate of 28.2 μmol l(-1) h(-1) and a specific production rate of 5.06 μmol(-1) g(-1) (DCW) h(-1) . These results highlight the efficacy of the treatment applied to JAJ in making this agromaterial a promising low-cost renewable feedstock for improved BDS by the fructophilic strain 1B. This study is a fundamental step viewing BDS application at the industrial level as it accounts a cost-effective production of the biocatalysts, one of the main drawbacks for BDS scale-up.