A new impetus for biodesulfurization: bypassing sulfate inhibition in biocatalyst production

Abstract

Biodesulfurization is a biotechnological process that employs microorganisms as biocatalysts to remove sulfur from fuels usually at mesophilic conditions, targeting recalcitrant organosulfur compounds without affecting their hydrocarbon structure. One of...

Streamlining the biodesulfurization process: development of an integrated continuous system prototype using Gordonia alkanivorans strain 1B

“…Taking into consideration that this system would integrate the continuous biocatalyst production method described above, three factors were selected for these initial studies: (1) organic : aqueous ratio – higher ratios are ideal for industrial purposes, however, they can have adverse effects on biological activity and mass transfer, which could affect BDS activity; 40 (2) DBT concentration – the response to different concentrations can determine the potential of the biocatalyst, as DBT and especially the 2-HBP, resulting from its desulfurization, are known to be toxic at higher levels. 26,41 In Silva et al , 20 BDS by strain 1B was studied with 250 μM of DBT, as such it was important to understand its behavior/potential to deal with greater concentrations; and (3) biocatalyst concentration – effectiveness at low concentrations would be ideal, but the increase in concentration could also mitigate adverse effects caused by toxicity and/or compensate lower biocatalyst activity. 26…”

“…Despite these interesting characteristics, BDS presents some limitations that are intrinsic to its biological nature: it has very low reaction rates, resulting in a slower process; it is inhibited by easily metabolized/easy access sulfur sources; the biocatalysts (the microorganisms) must be maintained under optimal conditions for their growth/metabolic activity and can be affected by the toxicity of compounds present in the fuels. 17–21 Furthermore, there is currently a lack of a well-defined BDS model system, that defines how to produce and employ the biocatalyst, since different works often suggest opposite approaches to obtain optimal results. Additionally, most studies tend to focus on how to improve BDS rates, without considering the applicability of the proposed models.…”

“…14–16,36 These characteristics make strain 1B especially interesting for modern biotechnological applications, allowing the exploration of different feedstocks for cultivation and the coproduction of multiple products, potentially increasing the viability of a future BDS biorefinery. Moreover, in Silva et al , 20 when the strain 1B was cultivated using the novel continuous production method, it demonstrated greater biomass production and biodesulfurization rates than Rhodococcus erythropolis D1 following the same cultivation method.…”

“…Recently, an innovative method was reported for the continuous cultivation of biocatalysts with BDS activity using easy-access and low-cost sulfur sources. 20 This method allowed the production of biocatalysts for BDS using inhibitory sulfur sources, without the need for induction, specific carbon sources, nor genetic manipulation, and without reducing BDS activity nor biomass production. The development of this continuous production method opened the possibility of integrating biocatalyst production and BDS into a single continuous process, which can be used to streamline the BDS process, bypassing many of its limitations, making it closer to large scale application.…”

“…However, despite the promising results, the study of Silva et al 20 was mostly centered on continuous biocatalyst production and BDS was always preceded by a biocatalyst washing and concentration step, which made it impossible to perform a direct integration of this production method with a continuous BDS process. Furthermore, BDS was only assessed in batch conditions through resting cells assays in which DBT was in aqueous suspensions.…”