Harnessing Pseudodesulfovibrio sp., a sulfate-reducing bacterium for the sustainable synthesis of cerium sulfide.

The present study investigates a novel sulfate-reducing bacterium, Pseudodesulfovibrio sp. MCM B-508, isolated from produced water, for its ability to produce cerium sulfide, an industrially valuable rare earth colorant. The study demonstrates a microbial route for pigment synthesis by cloning and expressing dissimilatory sulfite reductase (dsrAB) genes from this bacterium in Escherichia coli. The enzyme dissimilatory sulfite reductase shared a maximum of 94.09% homology with published dissimilatory sulfite reductase sequences from the GenBank database, highlighting its novelty. Using molecular engineering techniques, including chaperone co-expression with the pGro7 vector, the sulfate conversion efficiency was significantly enhanced to 71.23%, overcoming limitations in sulfate-reducing bacterial processes. The research successfully converted cerium sulfate to the desired gamma-form cerium sulfide (Ce₂S₃) through a recombinant E. coli strain, achieving a more efficient and eco-friendly production method compared to conventional chemical synthesis approaches. X-ray diffraction analysis confirmed the formation of the targeted pigment, with major peaks at 25.3 and 32.8° 2θ, demonstrating the potential for an industrially viable, sustainable pigment production process.