Sulfobacillus benefaciens sp. nov., an acidophilic facultative anaerobic Firmicute isolated from mineral bioleaching operations

Abstract

Gram-positive bacteria found as the sole Firmicutes present in two mineral bioleaching stirred tanks, and a third bacterium isolated from a heap leaching operation, were shown to be closely related to each other but distinct from characterized acidophilic iron- and sulfur-oxidizing bacteria of the genus Sulfobacillus, to which they were affiliated. One of the isolates (BRGM2) was shown to be a thermo-tolerant (temperature optimum 38.5 degrees C, and maximum 47 degrees C) obligate acidophile (pH optimum 1.5, and minimum 0.8), and also noted to be a facultative anaerobe, growing via ferric iron respiration in the absence of oxygen. Although isolates BRGM2 and TVK8 were able to metabolize many monomeric organic substrates, their propensity for autotrophic growth was found to be greater than that of Sulfobacillus thermosulfidooxidans and the related acidophile, Sb. acidophilus. Faster growth rates of the novel isolates in the absence of organic carbon was considered to be a major reason why they, rather than Sb. thermosulfidooxidans (which shared many physiological characteristics) more successfully exploited conditions in the stirred tanks. Based on their phylogenetic and phenotypic characteristics, the isolates are designated strains of the proposed novel species, Sulfobacillus benefaciens, with isolate BRGM2 nominated as the type strain.

Heterotrophic Archaea Contribute to Carbon Cycling in Low-pH, Suboxic Biofilm Communities

“…tend to be in lower relative abundance (4). Studies have indicated that species of Sulfobacillus are facultative anaerobes capable of both autotrophic and heterotrophic modes of growth (22,35). Oxidation of Fe(II), S 0 , and sulfide minerals, anaerobic reduction of Fe(III), and utilization of yeast extract, glucose, mannose, and other carbon sources have been described for various Sulfobacillus species (22,35).…”

“…Studies have indicated that species of Sulfobacillus are facultative anaerobes capable of both autotrophic and heterotrophic modes of growth (22,35). Oxidation of Fe(II), S 0 , and sulfide minerals, anaerobic reduction of Fe(III), and utilization of yeast extract, glucose, mannose, and other carbon sources have been described for various Sulfobacillus species (22,35). Sulfobacillus species were detected predominantly in 5-way biofilms, but we have not clearly identified ecological roles for these organisms: their broad metabolic capabilities may be indicative of a generalist ecological strategy.…”

Two Large, Related, Cryptic Plasmids from Geographically Distinct Isolates of Sulfobacillus thermotolerans

“…To date, five species have been differentiated phenotypically as well as by 16S rRNA gene sequence analysis. Sulfobacillus thermosulfidooxidans (16) appears to be the most active in oxidation of iron and mineral sulfides and is commonly isolated from biomining operations, while S. benefaciens (19) has been less frequently isolated from similar processes. The species more commonly isolated from natural environments include Sulfobacillus acidophilus (30), Sulfobacillus sibiricus (26), and Sulfobacillus thermotolerans (4).…”

Bioleaching of an organic-rich polymetallic concentrate using stirred-tank technology

“…benefaciens therefore favoured when growing in autotrophic conditions in continuous stirred tank system (Rawlings, 2005;Johnson et al, 2008).…”