Chemolithoautotrophic oxidation of thiosulfate, tetrathionate and thiocyanate by a novel rhizobacterium belonging to the genus Paracoccus


  • Present address: Wriddhiman Ghosh, Department of Microbiology, University of Burdwan, Golapbag, Burdwan 713 104, West Bengal, India.

  • Editor: J. Murrell

Correspondence: Wriddhiman Ghosh, Department of Microbiology, Bose Institute, P-1/12, C. I. T. Scheme VII-M, Kolkata 700 054, India. Tel.: +91 33 2355 9416; fax: +91 33 2355 3886; e-mail:


Two tropical leguminous-rhizospheric strains, SST and JT 001, phylogenetically closest to Paracoccus thiocyanatus and Paracoccus pantotrophus, respectively, were isolated on reduced sulfur compounds as sole energy and electron sources. While SST had versatile chemolithotrophic abilities to oxidize thiosulfate, tetrathionate, thiocyanate, sulfide and elemental sulfur, JT 001 could oxidize thiosulfate, soluble sulfide, elemental sulfur and a relatively lesser amount of tetrathionate. Positive hybridization signals were detected for JT 001 but not SST, when their genomic DNAs were probed with DIG-labeled sulfur oxidation genes amplified from the chemolithotrophic alphaproteobacterium Pseudaminobacter salicylatoxidans KCT001. Though the new isolate SST exhibited high 16S rRNA gene sequence similarity with the monotypic species P. thiocyanatus, it was found to be considerably distinct from the latter in terms of phenotypic and chemotaxonomic characteristics. Polyphasic systematic analysis, however, confirmed that JT 001 was a strain of P. pantotrophus.