A Case of Predominance of Alicyclobacillus tolerans in Microbial Community during Bioleaching of Pentlandite-Chalcopyrite Concentrate

Abstract

Bacterial isolates assigned to the species Alicyclobacillus tolerans, which occupies an intermediate position between an organotrophic genus Alicyclobacillus and mixotrophic genus Sulfobacillus, were revealed as members of the acidophilic chemolithotrophic community during stirred-tank bioleaching of violarite–pentlandite–chalcopyrite concentrate at 40 °C. Surprisingly, this species succeeded more common iron-oxidizing community members after a series of bioleaching processes in bioreactors. The possibility of mixotrophic and organoheterotrophic growth of Al. tolerans, tolerance to low pH values (1.0–1.15), as well as preservation of cells via sporulation under unfavorable conditions, may explain its key role in the bioleaching of the copper–nickel bulk concentrate. Isolation of two other sulfur-oxidizing pure cultures dominating the microbial community, together with their phylogenetic characterization, allowed the assignment of these isolates to the species Acidithiobacillus caldus. This and other studies of acidophilic microbial communities are important for the development and intensification of the bioleaching processes, including a biobeneficiation approach previously proposed by us.

First description of the microbial diversity in the Amarillo River (La Rioja, Argentina); a natural extreme environment where the whole microbial community paints the landscape yellow

“…tolerans AMF was the main iron oxidiser in the bioleaching of a violarite-pentlandite-chalcopyrite concentrate highlighting the role of mixotrophs in this kind of processes. As in culture RA8-30H the Alicyclobacillus strain was accompanied, though in lesser abundances, by Acidithiobacillus species and other iron and/or sulphur oxidiser [40]. Another study showed that Al.…”

“…Although different Alicyclobacillus species are frequently detected in molecular ecology surveys in highly acidic extreme environments, natural or anthropogenically generated ([18], [38]), they have rarely been isolated, and consequently studied especially at genomic level. In spite being mainly heterotrophs, in many cases Alicyclobacillus are the predominant iron oxidising species, even though they generally do it at lower rates than other mesophilic or moderate thermophilic iron oxidisers ( [40], [41]). Al.…”

The First Description of the Microbial Diversity in the Amarillo River (La Rioja, Argentina), a Natural Extreme Environment Where the Whole Microbial Community Paints the Landscape Yellow

“…Although different Alicyclobacillus species are frequently detected in molecular ecology surveys in highly acidic extreme environments, natural or anthropogenically generated ([ 3 , 24 ]), they have rarely been isolated and consequently studied, especially at the genomic level. In spite of being mainly heterotrophs, in many cases, Alicyclobacillus are the predominant iron-oxidising species, even though they generally oxidise at lower rates than other mesophilic or moderate thermophilic iron oxidisers ([ 45 , 46 ]). Al.…”

“…tolerans AMF was the main iron oxidiser in the bioleaching of a violarite–pentlandite–chalcopyrite concentrate, highlighting the role of mixotrophs in this kind of process. As in culture RA8-30H, the Alicyclobacillus strain was accompanied, although in lesser abundances, by Acidithiobacillus species and other iron and/or sulphur oxidisers [ 45 ]. Another study showed that Al.…”

Old Sulfidic Ore Tailing Dump: Ground Features, Mineralogy, Biodiversity—A Case Study from Sibay, Russia

“…These acidophilic archaea oxidize ferrous iron at low pH values in the presence of small amounts of organic material. They are commonly reported as members of acidophilic communities in sulfide ore deposits, processes of bioleaching of sulfide raw materials, and AMD [34,39,40]. The proportion of Pseudomonas spp.…”