Novel bacterial sulfur oxygenase reductases from bioreactors treating gold-bearing concentrates

Abstract

The microbial community and sulfur oxygenase reductases of metagenomic DNA from bioreactors treating gold-bearing concentrates were studied by 16S rRNA library, real-time polymerase chain reaction (RT-PCR), conventional cultivation, and molecular cloning. Results indicated that major bacterial species were belonging to the genera Acidithiobacillus, Leptospirillum, Sulfobacillus, and Sphingomonas, accounting for 6.3, 66.7, 18.8, and 8.3%, respectively; the sole archaeal species was Ferroplasma sp. (100%). Quantitative RT-PCR revealed that the 16S rRNA gene copy numbers (per gram of concentrates) of bacteria and archaea were 4.59 x 10(9) and 6.68 x 10(5), respectively. Bacterial strains representing Acidithiobacillus, Leptospirillum, and Sulfobacillus were isolated from the bioreactors. To study sulfur oxidation in the reactors, pairs of new PCR primers were designed for the detection of sulfur oxygenase reductase (SOR) genes. Three sor-like genes, namely, sor (Fx), sor (SA), and sor (SB) were identified from metagenomic DNAs of the bioreactors. The sor (Fx) is an inactivated SOR gene and is identical to the pseudo-SOR gene of Ferroplasma acidarmanus. The sor (SA) and sor (SB) showed no significant identity to any genes in GenBank databases. The sor (SB) was cloned and expressed in Escherichia coli, and SOR activity was determined. Quantitative RT-PCR determination of the gene densities of sor (SA) and sor (SB) were 1,000 times higher than archaeal 16S rRNA gene copy numbers, indicating that these genes were mostly impossible from archaea. Furthermore, with primers specific to the sor (SB) gene, this gene was PCR-amplified from the newly isolated Acidithiobacillus sp. strain SM-1. So far as we know, this is the first time to determine SOR activity originating from bacteria and to document SOR gene in bioleaching reactors and Acidithiobacillus species.

Distribution, Diversity, and Activities of Sulfur Dioxygenases in Heterotrophic Bacteria

“…Chemolithotrophs employ multiple systems for sulfur oxidation (32), including sulfur oxygenase reductase (SOR) and SDO. SOR converts S 0 to sulfide, thiosulfate, and sulfite (33,34). On the other hand, SDOs oxidize sulfur to sulfite (35).…”

Community genomic analysis of an extremely acidophilic sulfur-oxidizing biofilm

“…There is no evidence for soxCD, or for flavocytochrome C or dissimilatory sulfite reductase (DSR). We did not retrieve any sequences matching the recently identified bacterial sulfur oxygenase-reductase genes (Chen et al, 2007), including the predicted sulfur oxygenase-reductase in Acidithiobacillus caldus (Valdés et al, 2009).…”

The Genome Sequence of the Metal-Mobilizing, Extremely Thermoacidophilic Archaeon Metallosphaera sedula Provides Insights into Bioleaching-Associated Metabolism

“…Certain terminal oxidase components have been expressed in extremely thermoacidophilic archaea grown on specific RISCs (36,54). Although not directly linked to electron transport, sulfur oxygenase reductases (Sor) are believed to be important for breakdown of intracellular RISCs, particularly S 0 or polysulfides (11,37,69 Although M. sedula presumably grows mixotrophically, autotrophy is critical in biomining environments, where relatively small amounts of organic carbon are available. Several members of the Sulfolobales, including M. sedula, purportedly fix carbon (CO 2 ) via a modified 3-hydroxypropionate cycle, identified in Chloroflexus aurantiacus (31-34, 43, 67).…”