Microbial transport systems of organic sulfur compounds: Diversity and implications for biocatalysis, healthcare, and environmental biotechnology

The global sulfur cycle plays a vital role in human health, global warming, and biogeochemistry. Organic sulfur compounds constitute a substantial sulfur reservoir and serve as an energy and/or carbon source for prokaryotes. In addition, microbial interactions with organic sulfur compounds are pivotal for several biotechnological applications in petroleum biorefining, industrial biocatalysis, bioremediation, healthcare, and plant growth promotion. Microbial degradation of organic sulfur compounds is hindered by slow degradation rates, substrate specificity, toxicity of by-products, and challenges in scalability and efficiency. While degradation pathways of some organic sulfur compounds have been elucidated, transport systems involved in their uptake and efflux remain less explored. Regulating the uptake and efflux of organic sulfur compounds in microorganisms can help overcome several of the limitations associated with their transformation. Membrane transporters are not only crucial for the uptake and efflux of organic sulfur compounds but also play a key role in stress tolerance by facilitating the excretion of toxic metabolites. Understanding the intricacies of these transporters provides valuable insights into microbial ecology and the development of strategies for harnessing microbial sulfur metabolism for important biotechnological applications. This review systematically presents the diversity, mechanisms, and potential evolution pathways of microbial membrane transporters involved in organic sulfur compounds acquisition. Furthermore, it highlights and discusses advances in the characterization of transporter systems and current limitations in using transporter systems for fuel biodesulfurization and organic sulfur compound degradation. Eventually, we explore the implications of organic sulfur compounds transporters in biotechnology and identify future research directions toward leveraging the biotechnological potential of microbial sulfur metabolism, fueled by advanced techniques of systems microbiology, metabolic engineering, as well as artificial intelligence.