scholarly journals Biofilm Formation Is Crucial for Efficient Copper Bioleaching From Bornite Under Mesophilic Conditions: Unveiling the Lifestyle and Catalytic Role of Sulfur-Oxidizing Bacteria

2021 ◽  
Vol 12 ◽  
Author(s):  
Roberto A. Bobadilla-Fazzini ◽  
Ignacio Poblete-Castro
Keyword(s):  
Biofilm Formation ◽  
Mining Industry ◽  
Copper Recovery ◽  
Acidithiobacillus Thiooxidans ◽  
Cu Content ◽  
Planktonic Form ◽  
A Cell ◽  
Catalytic Role ◽  
Sulfur Oxidizing

Biofilm formation within the process of bioleaching of copper sulfides is a relevant aspect of iron- and sulfur-oxidizing acidophilic microorganisms as it represents their lifestyle in the actual heap/dump mining industry. Here, we used biofilm flow cell chambers to establish laminar regimes and compare them with turbulent conditions to evaluate biofilm formation and mineralogic dynamics through QEMSCAN and SEM-EDS during bioleaching of primary copper sulfide minerals at 30°C. We found that laminar regimes triggered the buildup of biofilm using Leptospirillum spp. and Acidithiobacillus thiooxidans (inoculation ratio 3:1) at a cell concentration of 106 cells/g mineral on bornite (Cu5FeS4) but not for chalcopyrite (CuFeS2). Conversely, biofilm did not occur on any of the tested minerals under turbulent conditions. Inoculating the bacterial community with ferric iron (Fe3+) under shaking conditions resulted in rapid copper recovery from bornite, leaching 40% of the Cu content after 10 days of cultivation. The addition of ferrous iron (Fe2+) instead promoted Cu recovery of 30% at day 48, clearly delaying the leaching process. More efficiently, the biofilm-forming laminar regime almost doubled the leached copper amount (54%) after 32 days. In-depth inspection of the microbiologic dynamics showed that bacteria developing biofilm on the surface of bornite corresponded mainly to At. Thiooxidans, while Leptospirillum spp. were detected in planktonic form, highlighting the role of biofilm buildup as a means for the bioleaching of primary sulfides. We finally propose a mechanism for bornite bioleaching during biofilm formation where sulfur regeneration to sulfuric acid by the sulfur-oxidizing microorganisms is crucial to prevent iron precipitation for efficient copper recovery.

scholarly journals Role of the Streptococcus mutans irvA Gene in GbpC-Independent, Dextran-Dependent Aggregation and Biofilm Formation

2009 ◽  
Vol 75 (22) ◽  
pp. 7037-7043 ◽  
Author(s):  
Min Zhu ◽  
Dragana Ajdić ◽  
Yuan Liu ◽  
David Lynch ◽  
Justin Merritt ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Growth Conditions ◽  
Parental Background ◽  
A Cell ◽  
Major Surface ◽  
Biofilm Development ◽  
Small Aggregation

ABSTRACT Dextran-dependent aggregation (DDAG) of Streptococcus mutans is an in vitro phenomenon that is believed to represent a property of the organism that is beneficial for sucrose-dependent biofilm development. GbpC, a cell surface glucan-binding protein, is responsible for DDAG in S. mutans when cultured under defined stressful conditions. Recent reports have described a putative transcriptional regulator gene, irvA, located just upstream of gbpC, that is normally repressed by the product of an adjacent gene, irvR. When repression of irvA is relieved, there is a resulting increase in the expression of GbpC and decreases in competence and synthesis of the antibiotic mutacin I. This study examined the role of irvA in DDAG and biofilm formation by engineering strains that overexpressed irvA (IrvA+) on an extrachromosomal plasmid. The IrvA+ strain displayed large aggregation particles that did not require stressful growth conditions. A novel finding was that overexpression of irvA in a gbpC mutant background retained a measure of DDAG, albeit very small aggregation particles. Biofilms formed by the IrvA+ strain in the parental background possessed larger-than-normal microcolonies. In a gbpC mutant background, the overexpression of irvA reversed the fragile biofilm phenotype normally associated with loss of GbpC. Real-time PCR and Northern blot analyses found that expression of gbpC did not change significantly in the IrvA+ strain but expression of spaP, encoding the major surface adhesin P1, increased significantly. Inactivation of spaP eliminated the small-particle DDAG. The results suggest that IrvA promotes DDAG not only by GbpC, but also via an increase in P1.

scholarly journals The Terminal A Domain of the Fibrillar Accumulation-Associated Protein (Aap) of Staphylococcus epidermidis Mediates Adhesion to Human Corneocytes

2009 ◽  
Vol 191 (22) ◽  
pp. 7007-7016 ◽  
Author(s):  
Robin L. Macintosh ◽  
Jane L. Brittan ◽  
Ritwika Bhattacharya ◽  
Howard F. Jenkinson ◽  
Jeremy Derrick ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Domain Architecture ◽  
Opportunistic Pathogen ◽  
Additional Function ◽  
Artificial Joints ◽  
A Cell ◽  
Skin Colonization ◽  
Accumulation Associated Protein

ABSTRACT The opportunistic pathogen Staphylococcus epidermidis colonizes indwelling medical devices by biofilm formation but is primarily a skin resident. In many S. epidermidis strains biofilm formation is mediated by a cell wall-anchored protein, the accumulation-associated protein (Aap). Here, we investigate the role of Aap in skin adhesion. Aap is an LPXTG protein with a domain architecture including a terminal A domain and a B-repeat region. S. epidermidis NCTC 11047 expresses Aap as localized, lateral tufts of fibrils on one subpopulation of cells (Fib+), whereas a second subpopulation does not express these fibrils of Aap (Fib−). Flow cytometry showed that 72% of NCTC 11047 cells expressed Aap and that 28% of cells did not. Aap is involved in the adhesion of Fib+ cells to squamous epithelial cells from the hand (corneocytes), as the recombinant A-domain protein partially blocked binding to corneocytes. To confirm the role of the Aap A domain in corneocyte attachment, Aap was expressed on the surface of Lactococcus lactis MG1363 as sparsely distributed, peritrichous fibrils. The expression of Aap increased corneocyte adhesion 20-fold compared to L. lactis carrying Aap without an A domain. S. epidermidis isolates from catheters, artificial joints, skin, and the nose also used the A domain of Aap to adhere to corneocytes, emphasizing the role of Aap in skin adhesion. In addition, L. lactis expressing Aap with different numbers of B repeats revealed a positive correlation between the number of B repeats and adhesion to corneocytes, suggesting an additional function for the B region in enhancing A-domain-dependent attachment to skin. Therefore, in addition to its established role in biofilm formation, Aap can also promote adhesion to corneocytes and is likely to be an important adhesin in S. epidermidis skin colonization.

scholarly journals Comparative Analysis of Attachment to Chalcopyrite of Three Mesophilic Iron and/or Sulfur-Oxidizing Acidophiles

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 406 ◽  
Author(s):  
Qian Li ◽  
Baojun Yang ◽  
Jianyu Zhu ◽  
Hao Jiang ◽  
Jiaokun Li ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Bacterial Attachment ◽  
Copper Recovery ◽  
Metal Sulfides ◽  
Acidithiobacillus Thiooxidans ◽  
Adhesion Forces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Initial Adhesion ◽  
Sulfur Oxidizing

Adhesion plays an important role in bacterial dissolution of metal sulfides, since the attached cells initiate the dissolution. In addition, biofilms, forming after bacterial attachment, enhance the dissolution. In this study, interactions between initial adhesion force, attachment behavior and copper recovery were comparatively analyzed for Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferrooxidans during bioleaching of chalcopyrite. The adhesion forces between bacteria and minerals were measured by atomic force microscopy (AFM). L. ferrooxidans had the largest adhesion force and attached best to chalcopyrite, while A. ferrooxidans exhibited the highest bioleaching of chalcopyrite. The results suggest that the biofilm formation, rather than the initial adhesion, is positively correlated with bioleaching efficiency.

Growth of Acidithiobacillus thiooxidans Biofilm on Glass, Concrete and Stoneware

2015 ◽  
Vol 227 ◽  
pp. 286-289 ◽  
Author(s):  
Weronika Dec ◽  
Beata Cwalina ◽  
Joanna Michalska ◽  
Daria Merkuda
Keyword(s):  
Incubation Time ◽  
Biofilm Formation ◽  
Essential Role ◽  
Acidithiobacillus Thiooxidans ◽  
Sulfur Oxidizing ◽  
Microbiologically Induced Corrosion ◽  
Comparable Intensity ◽  
Sulfur Oxidizing Bacteria

Biofilms formed by various microorganisms are often responsible for microbiologically induced corrosion of materials exposed to moisture. Many bacteria strains may form biofilms on different mineral materials including concrete and stoneware. Among them, the sulfur-oxidizing bacteria of Acidithiobacillus genus, especially of A. thiooxidans species play an essential role in these materials' destruction. In the present study we observed comparable intensity of A. thiooxidans growth on concrete and glass, and slower biofilm formation on stoneware. Prolongation of incubation time caused an increase in biomass of A. thiooxidans biofilm formed on glass and stoneware. Amongst the investigated mineral materials, the concrete proved to be the most susceptible to deterioration by A. thiooxidans bacteria.

Mineralogical Dynamics of Primary Copper Sulfides Mediated by Acidophilic Biofilm Formation

2017 ◽  
Vol 262 ◽  
pp. 325-329 ◽  
Author(s):  
Roberto A. Bobadilla-Fazzini
Keyword(s):  
Biofilm Formation ◽  
Copper Recovery ◽  
Process Conditions ◽  
Mineral Surface ◽  
Flow Conditions ◽  
Mineralogical Analysis ◽  
Acidophilic Microorganisms ◽  
Copper Sulfides ◽  
New Process ◽  
Sulfur Oxidizing

Bioleaching of copper sulfides is catalyzed by iron-and sulfur-oxidizing acidophilic microorganisms attached to the mineral surface forming a biofilm. However, the link between copper sulfides bioleaching and biofilm formation is not yet fully understood. Understanding the factors that are limiting the bioleaching kinetics for different copper sulfide minerals through exhaustive mineralogical analysis of the mineral surface with concomitant biofilm formation during the leaching process will deliver new process conditions with enhanced kinetics and higher copper recovery. In this work we have developed and standardized a reproducible flow cell method able to mimic heap/dump bioleaching laminar flow conditions to study the mineralogical dynamics by advanced mineralogical analysis including QEMSCAN and SEM-EDS coupled to biofilm formation analysis. Based on this method, the bioleaching mineralogical dynamics of primary copper sulfides (enargite (Cu3AsS4), chalcopyrite (CuFeS2) and bornite (Cu5FeS4)) have been determined in the presence of biofilm formation. Supported by the observed mineralogical dynamics, different mechanisms of dissolution for bioleaching were observed as well as selective biofilm formation over the mineral surface, showing enhanced conditions for copper recovery.

Effect of Galactose on EPS Production and Attachment of Acidithiobacillus thiooxidans to Mineral Surfaces

2017 ◽  
Vol 262 ◽  
pp. 476-481
Author(s):  
Paulina Aguirre ◽  
Aminael Sánchez Rodríguez ◽  
Juan Carlos Gentina ◽  
Axel Schippers
Keyword(s):  
Biofilm Formation ◽  
Microbial Growth ◽  
Extracellular Polymeric Substances ◽  
Elemental Sulfur ◽  
Culture Media ◽  
Acidithiobacillus Thiooxidans ◽  
Mineral Surfaces ◽  
Planktonic Cells ◽  
Cell Adherence ◽  
A Cell

The presence of extracellular polymeric substances (EPS) and their relevance for biofilm formation on the mineral surface for a variety of microbial species play a fundamental role in the degradation of sulfide ores. EPS production is associated with induction or auto induction mechanisms as a response of bacteria to environmental conditions. In this study, we tested galactose as an inducer of EPS production in planktonic cells of Acidithiobacillus thiooxidans DSM 14887T and their adherence to polymetallic mineral surfaces. Cells of At. thiooxidans were first adapted to grow at different concentrations of galactose (0.15, 0.25, 0.35%) using a modified 9K liquid medium and elemental sulfur as the energy source. In order to determine EPS production, the microorganisms were grown for 24 hours at different concentrations of galactose. Our results showed a cell adherence of 84% cells within 4 hours in presence of 0.15% galactose compared to 70% without galactose. The optimal concentration of galactose for maximal EPS production was 0.25% and for the attachment of cells it was 0.15%. Higher galactose concentrations inhibited microbial growth and decreased the number of cells attached to the mineral. While with a small amount of galactose in the culture media can shift the balance between sessile cells and planktonic cells, generating an increase in adhesion and therefore a possible increase of the bioleaching rate.

The sulfane sulfur of persulfides is the actual substrate of the sulfur-oxidizing enzymes from Acidithiobacillus and Acidiphilium spp.

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1699-1710 ◽  
Author(s):  
Thore Rohwerder ◽  
Wolfgang Sand
Keyword(s):  
Elemental Sulfur ◽  
Sulfide Oxidation ◽  
Sulfur Oxidation ◽  
Acidithiobacillus Thiooxidans ◽  
Sulfane Sulfur ◽  
Catalytic Role ◽  
Sulfur Oxidizing ◽  
Sulfur Containing ◽  
Actual Substrate ◽  
Sulfur Donor

To identify the actual substrate of the glutathione-dependent sulfur dioxygenase (EC 1.13.11.18) elemental sulfur oxidation of the meso-acidophilic Acidithiobacillus thiooxidans strains DSM 504 and K6, Acidithiobacillus ferrooxidans strain R1 and Acidiphilium acidophilum DSM 700 was analysed. Extraordinarily high specific sulfur dioxygenase activities up to 460 nmol min−1 (mg protein)−1 were found in crude extracts. All cell-free systems oxidized elemental sulfur only via glutathione persulfide (GSSH), a non-enzymic reaction product from glutathione (GSH) and elemental sulfur. Thus, GSH plays a catalytic role in elemental sulfur activation, but is not consumed during enzymic sulfane sulfur oxidation. Sulfite is the first product of sulfur dioxygenase activity; it further reacted non-enzymically to sulfate, thiosulfate or glutathione S-sulfonate (). Free sulfide was not oxidized by the sulfur dioxygenase. Persulfide as sulfur donor could not be replaced by other sulfane-sulfur-containing compounds (thiosulfate, polythionates, bisorganyl-polysulfanes or monoarylthiosulfonates). The oxidation of H2S by the dioxygenase required GSSG, i.e. the disulfide of GSH, which reacted non-enzymically with sulfide to give GSSH prior to enzymic oxidation. On the basis of these results and previous findings a biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp. is proposed.

scholarly journals Sequence analysis and confirmation of type IV pili-associated proteins PilY1, PilW and PilV in Acidithiobacillus thiooxidans

2018 ◽  
Author(s):  
Elvia Alfaro-Saldaña ◽  
O. Araceli Hernández-Sánchez ◽  
Araceli Soberano-Patrón ◽  
Marizel Astello-García ◽  
J. Alfredo Méndez-Cabañas ◽  
...  
Keyword(s):  
Mine Drainage ◽  
Protein Structures ◽  
Mining Industry ◽  
Type Iv Pili ◽  
Acidithiobacillus Thiooxidans ◽  
Type Iv ◽  
Cohesive Group ◽  
Associated Proteins ◽  
Sulfur Oxidizing ◽  
First Time

AbstractAcidithiobacillus thiooxidans is an acidophilic chemolithoautotrophic bacterium widely used in the mining industry due to its metabolic sulfur-oxidizing capability. The biooxidation of sulfide minerals is enhanced through the attachment of A. thiooxidans cells to the mineral surface. The Type IV pili (TfP) of At. thiooxidans may play an important role in the bacteria attachment, since among other functions, TfP play a key adhesive role in the attachment to and colonization of different surfaces. In this work, we reported for the first time the confirmed mRNA sequences of three TfP proteins from At. thiooxidans, the protein PilY1 and the TfP pilins PilW and PilV. The nucleotide sequences of these TfP proteins show changes of some nucleotide positions with respect to the corresponding annotated sequences. The bioinformatic analyses and 3D-modeling of protein structures sustain their classification as TfP proteins, as structural homologs of the corresponding proteins of P. aeruginosa, results that sustain the role of PilY1, PilW and PilV in pili assembly. Also, that PilY1 comprises the conserved Neisseria-PilC (superfamily) domain of the tip-associated adhesin, while PilW of the superfamily of putative TfP assembly proteins and PilV belongs to the superfamily of TfP assembly protein. Also, the analyses suggested the presence of specific functional domains involved in adhesion, energy transduction and signaling functions. The phylogenetic analysis indicated that the PilY1 of Acidithiobacillus genus forms a cohesive group linked with iron- and/or sulfur-oxidizing microorganisms from acid mine drainage or mine tailings. This work enriches knowledge regarding colonization, adhesion and biooxidation of inorganic sulfurs by A. thiooxidans.

scholarly journals LuxS Mediates Iron-Dependent Biofilm Formation, Competence, and Fratricide in Streptococcus pneumoniae

2011 ◽  
Vol 79 (11) ◽  
pp. 4550-4558 ◽  
Author(s):  
Claudia Trappetti ◽  
Adam J. Potter ◽  
Adrienne W. Paton ◽  
Marco R. Oggioni ◽  
James C. Paton
Keyword(s):  
Streptococcus Pneumoniae ◽  
Biofilm Formation ◽  
Extracellular Dna ◽  
Wild Type ◽  
Nasopharyngeal Colonization ◽  
Content Type ◽  
Planktonic Form ◽  
Dna Release ◽  
Amplification Loop

ABSTRACTDuring infection,Streptococcus pneumoniaeexists mainly in sessile biofilms rather than in planktonic form, except during sepsis. The capacity to form biofilms is believed to be important for nasopharyngeal colonization as well as disease pathogenesis, but relatively little is known about the regulation of this process. Here, we investigated the effect of exogenous iron [Fe(III)] as well as the role ofluxS(encoding S-ribosylhomocysteine lyase) on biofilm formation byS. pneumoniaeD39. Fe(III) strongly enhanced biofilm formation at concentrations of ≥50 μM, while Fe(III) chelation with deferoxamine was inhibitory. Importantly, Fe(III) also upregulated the expression ofluxSin wild-type D39. AluxS-deficient mutant (D39luxS) failed to form a biofilm, even with Fe(III) supplementation, whereas a derivative overexpressingluxS(D39luxS+) exhibited enhanced biofilm formation capacity and could form a biofilm without added Fe(III). D39luxSexhibited reduced expression of the major Fe(III) transporter PiuA, and the cellular [Fe(III)] was significantly lower than that in D39; in contrast, D39luxS+ had a significantly higher cellular [Fe(III)] than the wild type. The release of extracellular DNA, which is an important component of the biofilm matrix, also was directly related toluxSexpression. Similarly, genetic competence, as measured by transformation frequency as well as the expression of competence genescomD,comX,comW,cglA, anddltAand the murein hydrolasecbpD, which is associated with fratricide-dependent DNA release, all were directly related toluxSexpression levels and were further upregulated by Fe(III). Moreover, mutagenesis ofcbpDblocked biofilm formation. We propose that competence, fratricide, and biofilm formation are closely linked in pneumococci, and thatluxSis a central regulator of these processes. We also propose that the stimulatory effects of Fe(III) on all of these parameters are due to the upregulation ofluxSexpression, and that LuxS provides for a positive Fe(III)-dependent amplification loop by increasing iron uptake.

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