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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.


Microbial biomass after 4 (a) and 7 (b) days in cultures with samples obtained from two mine heaps (T and Q), at depths of 18 (Q18), 27 (T27), 54 (T54) and 63 (Q63) meters. h cultured with yeast extract, 2% w/v. Solid columns with As; columns with horizontal lines controls without As; bars standard errors.
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Fig1: Microbial biomass after 4 (a) and 7 (b) days in cultures with samples obtained from two mine heaps (T and Q), at depths of 18 (Q18), 27 (T27), 54 (T54) and 63 (Q63) meters. h cultured with yeast extract, 2% w/v. Solid columns with As; columns with horizontal lines controls without As; bars standard errors.

Mentions: According to the growth curves calculated for each selected culture, maximum biomass was reached at day 4 (Fig. 1). After 4 days, the biomass of the cultures containing 0.88 g/L As (11.7 mM) was not significantly different from that in the controls. The only exception was the Q63 culture, where biomass was significantly higher than in its corresponding control (Fig. 1a). At day 7, biomass decreased both in experimental (with As) and control (without As) cultures, with no significant difference between them (Fig. 1b). The main differences between experimental and control cultures were that in the experimental cultures, the pH decreased to <1, and As-rich precipitate was observed at the bottom of each tube on day 7.Fig. 1


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)

Microbial biomass after 4 (a) and 7 (b) days in cultures with samples obtained from two mine heaps (T and Q), at depths of 18 (Q18), 27 (T27), 54 (T54) and 63 (Q63) meters. h cultured with yeast extract, 2% w/v. Solid columns with As; columns with horizontal lines controls without As; bars standard errors.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig1: Microbial biomass after 4 (a) and 7 (b) days in cultures with samples obtained from two mine heaps (T and Q), at depths of 18 (Q18), 27 (T27), 54 (T54) and 63 (Q63) meters. h cultured with yeast extract, 2% w/v. Solid columns with As; columns with horizontal lines controls without As; bars standard errors.
Mentions: According to the growth curves calculated for each selected culture, maximum biomass was reached at day 4 (Fig. 1). After 4 days, the biomass of the cultures containing 0.88 g/L As (11.7 mM) was not significantly different from that in the controls. The only exception was the Q63 culture, where biomass was significantly higher than in its corresponding control (Fig. 1a). At day 7, biomass decreased both in experimental (with As) and control (without As) cultures, with no significant difference between them (Fig. 1b). The main differences between experimental and control cultures were that in the experimental cultures, the pH decreased to <1, and As-rich precipitate was observed at the bottom of each tube on day 7.Fig. 1

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.