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Community of thermoacidophilic and arsenic resistant microorganisms isolated from a deep profile of mine heaps.

Casas-Flores S, Gómez-Rodríguez EY, García-Meza JV - AMB Express (2015)

Bottom Line: We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4·½H2O).The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA.Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.

View Article: PubMed Central - PubMed

Affiliation: División de Biología Molecular, IPCYT, Camino a la Presa San José 2055, Lomas 4a, 78216, San Luis Potosí, SLP, México, scasas@ipicyt.edu.mx.

ABSTRACT
Soluble arsenic (As) in acidic feed solution may inhibit the copper (Cu) bioleaching process within mine heaps. To clarify the effect of soluble arsenic on the live biomass and bioxidative activity in heaps, toxicological assays were performed using a synthetic feed solution given by a mine company. The microorganisms had previously been isolated from two heap samples at up to 66 m depth, and cultured using specific media for chemolithotrophic acidophiles (pH 1-2) and moderate thermophiles (48°C), for arsenic tolerance assay. The four media with the highest biomass were selected to assay As-resistance; one culture (Q63h) was chosen to assay biooxidative activity, using a heap sample that contained chalcopyrite and covellite. We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4·½H2O). The arsenic tolerant community, as identified by 16S rDNA gene sequence analysis, was composed of three main metabolic groups: chemolithotrophs (Leptospirillum, Sulfobacillus); chemolithoheterotrophs and organoheterotrophs as Acidovorax temperans, Pseudomonas alcaligenes, P. mendocina and Sphingomonas spp. Leptospirillum spp. and S. thermosulfidooxidans were the dominant taxa in the Q63-66 cultures from the deepest sample of the oldest, highest-temperature heap. The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA. Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.

No MeSH data available.


Scanning electron micrograph and SEM-EDAX analysis of the UV-dried mine heap sample added to Erlenmeyer flasks during the biooxidative assays.
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Fig3: Scanning electron micrograph and SEM-EDAX analysis of the UV-dried mine heap sample added to Erlenmeyer flasks during the biooxidative assays.

Mentions: For the biooxidative assay in the presence of 0.5 g/L As (6.7 mM, added to the culture medium), heap sample Q63 was chosen, because no arsenic minerals had been detected therein, but chalcopyrite (CuFeS2) and the secondary Cu mineral, covellite (CuS; Fig. 3; Table 1) had been detected. Notably, microorganisms (~104 cells/mL) were observed in the control non-inoculated flasks after 21 days, because the heap sample was not entirely sterilized by UV.Fig. 3


Community of thermoacidophilic and arsenic resistant microorganisms isolated from a deep profile of mine heaps.

Casas-Flores S, Gómez-Rodríguez EY, García-Meza JV - AMB Express (2015)

Scanning electron micrograph and SEM-EDAX analysis of the UV-dried mine heap sample added to Erlenmeyer flasks during the biooxidative assays.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4539307&req=5

Fig3: Scanning electron micrograph and SEM-EDAX analysis of the UV-dried mine heap sample added to Erlenmeyer flasks during the biooxidative assays.
Mentions: For the biooxidative assay in the presence of 0.5 g/L As (6.7 mM, added to the culture medium), heap sample Q63 was chosen, because no arsenic minerals had been detected therein, but chalcopyrite (CuFeS2) and the secondary Cu mineral, covellite (CuS; Fig. 3; Table 1) had been detected. Notably, microorganisms (~104 cells/mL) were observed in the control non-inoculated flasks after 21 days, because the heap sample was not entirely sterilized by UV.Fig. 3

Bottom Line: We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4·½H2O).The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA.Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.

View Article: PubMed Central - PubMed

Affiliation: División de Biología Molecular, IPCYT, Camino a la Presa San José 2055, Lomas 4a, 78216, San Luis Potosí, SLP, México, scasas@ipicyt.edu.mx.

ABSTRACT
Soluble arsenic (As) in acidic feed solution may inhibit the copper (Cu) bioleaching process within mine heaps. To clarify the effect of soluble arsenic on the live biomass and bioxidative activity in heaps, toxicological assays were performed using a synthetic feed solution given by a mine company. The microorganisms had previously been isolated from two heap samples at up to 66 m depth, and cultured using specific media for chemolithotrophic acidophiles (pH 1-2) and moderate thermophiles (48°C), for arsenic tolerance assay. The four media with the highest biomass were selected to assay As-resistance; one culture (Q63h) was chosen to assay biooxidative activity, using a heap sample that contained chalcopyrite and covellite. We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4·½H2O). The arsenic tolerant community, as identified by 16S rDNA gene sequence analysis, was composed of three main metabolic groups: chemolithotrophs (Leptospirillum, Sulfobacillus); chemolithoheterotrophs and organoheterotrophs as Acidovorax temperans, Pseudomonas alcaligenes, P. mendocina and Sphingomonas spp. Leptospirillum spp. and S. thermosulfidooxidans were the dominant taxa in the Q63-66 cultures from the deepest sample of the oldest, highest-temperature heap. The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA. Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.

No MeSH data available.