SHORT COMMUNICATION Mining of genomic databases to identify novel biodesulfurizing microorganisms Sumedha Bhatia • Durlubh K. Sharma Received: 22 October 2009 / Accepted: 6 February 2010 / Published online: 20 February 2010 Ó Society for Industrial Microbiology 2010 Abstract The commercialization of the biocatalytic desulfurization process does not seem to be realistic in the near future because of the low desulfurization rate of the known microorganisms. Hence, the future development will depend on either genetically modifying the currently available bacteria or identifying novel biodesulfurizers. In this study an in silico method to identify new biode- sulfurizing microorganisms was adopted. By screening the available genomic databases, 13 novel desulfurizing microorganisms belonging to 12 genera were identified. Several of these could be of immense utility as they have both environment pollutant and industrial waste degrading capability. Keywords Biodesulfurization Á Genomic databases Á Fuel Á Thermophile Á Mesophile Upgrading the quality of fossil fuels to deal with sulfur- related environmental problems has been a major thrust in the recent past. This is mainly because of the stringent government regulations in several countries for lower levels of sulfur in transportation and non-road fuels [1]. Moreover petroleum refineries are also facing the problem of unavailability of low sulfur crudes, since the feedstock for refining processes are becoming heavier day by day with high sulfur contents [2, 3]. In the refineries hydrode- sulfurization (HDS) is the technology presently being used for the pre-combustion desulfurization of fuels. HDS involves the use of chemical catalysts containing metals at high pressures and temperatures. However, organic sulfur compounds such as dibenzothiophene (DBT) and its alkylated derivatives are found to be highly recalcitrant to HDS [4, 5]. Moreover, increasing generation of used up chemical catalysts as hazardous wastes is leading to the problem of their disposal. The past decade has seen the development of biocatalytic desulfurization (BDS) as an alternative or compliment to HDS for the removal of organic sulfur from fuels. BDS has the potential benefits of lower operating costs, production of fewer greenhouse gases and degradation of HDS recalcitrant organic sulfur compounds. These features would lead to high energy savings in the refinery in addition to being environmentally more benign [1]. The impetus for BDS was the discovery of the 4S pathway in Rhodococcus erythropolis IGTS8 [6]. Since then, various microorganisms have been characterized as possessing biodesulfurization ability [1]. The pathway deals with the removal of sulfur without affecting the carbon content and thus preserving the fuel value [7–9]. It involves four key enzymes: dibenzothiophene monoox- ygenase (DszC), dibenzothiophene sulfone monooxygen- ase (DszA), hydroxyphenyl benzene sulfonate (HPBS) desulfinase (DszB) and NADH:FMN oxidoreductase (DszD). Despite considerable progress in the field of BDS, microbial desulfurization up to now has not been that productive for many reasons, and therefore its commer- cialization is unlikely to take place in the near future [3]. These reasons include, but are not restricted to, (1) sulfur specificity, (2) activity, (3) broad spectrum, (4) mesophilic nature of the organisms, etc. Moreover, the known biode- sulfurizers have an approximately 500-fold lower desul- furization rate than what is required in industrial processes [10]. Hence, there exists a quest to identify and charac- terize new organisms that may have superior characteristics S. Bhatia Á D. K. Sharma (&) Center for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India e-mail: sharmadk@ces.iitd.ernet.in 123 J Ind Microbiol Biotechnol (2010) 37:425–429 DOI 10.1007/s10295-010-0697-6 Downloaded from https://academic.oup.com/jimb/article/37/4/425/6016464 by guest on 06 February 2023