Acidithiobacillus ferrooxidans oxidizes ferrous iron (Fe²⁺) to ferric iron (Fe³⁺), generating the primary oxidant for chemical attack of cobalt-bearing sulfide minerals. The enzymatic reaction (4Fe²⁺ + O₂ + 4H⁺ → 4Fe³⁺ + 2H₂O) couples oxygen reduction to iron oxidation, yielding energy for bacterial growth and CO₂ fixation. Ferric iron acts as a powerful oxidant that attacks framboidal pyrite surfaces where cobalt is concentrated, solubilizing both iron sulfides and associated cobalt minerals. The continuous regeneration of ferric iron by At. ferrooxidans maintains high oxidation potential in the bioleaching system, driving efficient cobalt and copper mobilization even from low-grade tailings (0.02% Co). This iron-cycling process represents the dominant energy-generating pathway for the consortium and is rate-limiting for overall metal recovery. -
+In the Rammelsberg laboratory enrichment, falling iron(II), increasing redox potential and dissolved iron support microbial iron(II)-to-iron(III) conversion that promotes metal-sulfide dissolution. The primary paper contrasts these dynamics with an inhibited abiotic control; it does not establish a rate-limiting step or reciprocal fitness between the two dominant taxa. The listed Acidithiobacillus taxa are dominant recorded members, not an exhaustive community or a demonstrated pairwise benefit.
-Source Taxon: Acidithiobacillus ferrooxidans
+Participating Taxa: + + Acidithiobacillus ferrooxidans, + + Acidithiobacillus thiooxidans + +
@@ -625,17 +624,6 @@Biological Processes:
-Ferric iron oxidizes sulfide minerals releasing cobalt and copper
+Microbial conversion of iron(II) to iron(III) supplies the chemical oxidant that promotes sulfide dissolution and associated metal release, as interpreted from the Rammelsberg reactor chemistry and abiotic comparison.
Ferric iron generated by At. ferrooxidans chemically oxidizes cobalt-bearing framboidal pyrite and copper sulfides (chalcopyrite, covellite) in the Rammelsberg tailings. The reaction attacks pyrite surfaces where cobalt is concentrated, releasing Co²⁺, Cu²⁺, Fe²⁺, and sulfate into solution. Mineralogical analysis confirmed that cobalt occurs on the surface of framboidal pyrite and is mainly leached by microbial attack. The consortium achieved 91% cobalt recovery and 57% copper recovery from bulk tailings (Co 0.02%, Cu 0.12%) after 13 days at 10% pulp density in stirred tank reactors. From flotation concentrate (Co 0.06%, Cu 0.57%), recovery was 66% cobalt and 33% copper. The ferric-mediated oxidation represents the dominant metal solubilization mechanism (indirect bioleaching), with ferrous iron released during mineral oxidation being recycled back to At. ferrooxidans for re-oxidation, creating a closed iron redox cycle. -
+The Rammelsberg enrichment achieved 91% cobalt and 57% copper extraction from bulk tailings after 13 days in laboratory stirred-tank reactors; flotation concentrate yielded 66% cobalt and 33% copper. Mineral analysis associates cobalt with framboidal pyrite, and the authors interpret greater cobalt dissolution than in the abiotic control as microbial/ferric-iron attack. These are community and mineral outcomes, not demonstrated mutualism or a closed partner-specific iron cycle. The listed Acidithiobacillus taxa are dominant recorded members, not an exhaustive community or a demonstrated pairwise benefit.
+ -Source Taxon: Acidithiobacillus ferrooxidans
+Participating Taxa: + Acidithiobacillus ferrooxidans, -
Target Taxon: Acidithiobacillus thiooxidans
+ Acidithiobacillus thiooxidans + + @@ -711,21 +701,6 @@Fe²⁺ released from mineral oxidation is recycled to At. ferrooxidans
-Elemental sulfur produced during mineral oxidation is substrate for At. thiooxidans
-Acidithiobacillus thiooxidans oxidizes elemental sulfur (S⁰) that accumulates as a passivation layer on sulfide mineral surfaces during ferric iron attack. The oxidation reaction (S²⁻ + 2H₂O + 2O₂ → SO₄²⁻ + 4H⁺) produces sulfuric acid, maintaining the low pH (pH 1.5-2.5) required for ferric iron solubility and optimal acidophilic bacterial activity. Removal of the elemental sulfur passivation layer is essential for sustained bioleaching kinetics, as sulfur accumulation would otherwise block access of ferric iron and bacteria to fresh mineral surfaces. At. thiooxidans employs the sox system (soxAX, soxB, soxCD, soxYZ), sulfide oxidoreductase (SQR), and sulfur dioxygenase (SDO) to catalyze sulfur oxidation. The sulfuric acid produced lowers pH, solubilizes additional metals through acid leaching, and creates the extreme acidic environment that excludes neutrophilic competitors, maintaining consortium dominance. This sulfur-oxidizing function is synergistic with At. ferrooxidans iron oxidation, as the two organisms together prevent both ferric hydroxide precipitation (through low pH) and sulfur passivation. -
+Rammelsberg shake-flask bioleaching decreased pH, whereas uninoculated inhibited controls increased in pH; the authors attribute the decrease to sulfuric-acid production by sulfide and sulfur biooxidation. This is a community acidification process. The source does not isolate an Acidithiobacillus thiooxidans-specific passivation-removal pathway, the named enzyme systems, or acidification-mediated benefit to Acidithiobacillus ferrooxidans. The listed Acidithiobacillus taxa are dominant recorded members, not an exhaustive community or a demonstrated pairwise benefit.
-Source Taxon: Acidithiobacillus thiooxidans
+Participating Taxa: + + Acidithiobacillus ferrooxidans, + + Acidithiobacillus thiooxidans + +
@@ -807,16 +786,6 @@Low pH maintained by sulfuric acid prevents ferric iron precipitation
-Both Acidithiobacillus ferrooxidans and At. thiooxidans are obligate chemolithoautotrophs that fix atmospheric CO₂ via the Calvin-Benson-Bassham cycle using energy derived from iron or sulfur oxidation. This autotrophic metabolism eliminates the need for organic carbon supplementation in the bioleaching system, reducing operational costs and enabling growth on the inorganic tailings substrate alone. Carbon fixation couples to the primary energy-generating reactions (iron and sulfur oxidation), with ATP and reducing equivalents (NADH) produced from chemolithotrophic electron transport chains driving CO₂ assimilation into biomass. The autotrophic growth strategy is well-adapted to the extreme oligotrophic conditions of acidic mine tailings where organic carbon is scarce, allowing the consortium to thrive and catalyze metal mobilization without external organic nutrients. -
- -Source Taxon: Acidithiobacillus ferrooxidans
- - - -Target Taxon: Acidithiobacillus thiooxidans
+ + +Metabolites: +
The correct primary study is doi:10.1016/j.hydromet.2020.105443;105484 concerns Finnish secondary ore, while PMID:39770610 is a general review. The inoculum contained four named strains and indigenous organisms were detected. Dominance by the two recorded Acidithiobacillus taxa does not establish a defined two-member community or reciprocal fitness. General iron/sulfur chemistry is not a demonstrated partner-specific recycling/passivation feedback, and intrinsic carbon fixation is not commensal exchange. Retain supported community processes and the iron-to-mineral-dissolution arrow without the other three feedback arrows or carbon-fixation interaction. Non-graph identity, industrial-scale and citation claims require separate curation under issue1753.
- carbon dioxide - (CHEBI:16526), +Attaches to: ecological_interactions#Iron Oxidation and Ferric Iron Generation, ecological_interactions#Cobalt and Copper Mobilization from Sulfide Minerals, ecological_interactions#Sulfur Oxidation and Acid Generation
Biological Processes:
-Some indigenous bacteria (~19%) were detected at the end of the leaching tests in STR
+The exact study explicitly reports additional community members.
+The mixed consortium containing mainly At. ferrooxidans and At. thiooxidans remained stable throughout the experiment.
+Supports these taxa as dominant, not exclusive or proven reciprocal beneficiaries.
+YL-JM2C-generated 2,4-dibromophenol is subsequently converted to 3,5-dibromocatechol by JMP134 TfdB.
Cupriavidus necator JMP134 hydroxylase TfdB converts the YL-JM2C dead-end 2,4-dibromophenol product to 3,5-dibromocatechol, linking YL-JM2C's initial BDE-47 attack to the downstream ortho-cleavage pathway shared by both strains.
+Cupriavidus necator JMP134 hydroxylase TfdB converts the YL-JM2C dead-end 2,4-dibromophenol product to 3,5-dibromocatechol, linking YL-JM2C's initial BDE-47 attack to the downstream ortho-cleavage pathway shared by both strains. This is the recipient conversion step in the diffusible cross-feeding relay, not evidence of a reverse metabolite transfer or improved YL-JM2C fitness. Both strains having a downstream pathway does not demonstrate exchange of 3,5-DBC back to YL-JM2C.
-Source Taxon: Cupriavidus necator JMP134
+Participating Taxa: + + Rhizorhabdus wittichii YL-JM2C, + + Cupriavidus necator JMP134 -
Target Taxon: Rhizorhabdus wittichii YL-JM2C
+ @@ -721,8 +724,8 @@Removal of the 2,4-DBP bottleneck connects the two isolate pathways and enables community-level BDE-47 degradation.
+ → Consortium BDE-47 removal without 2,4-DBP accumulation +JMP134 conversion of the YL-JM2C-derived 2,4-DBP prevents that intermediate from accumulating during consortium treatment. It is not required for disappearance of the parent BDE-47, which also occurred in the YL-JM2C monoculture.
The mixed YL-JM2C/JMP134 consortium removes BDE-47 from minimal salts medium, releases bromide during low-concentration BDE-47 degradation, and fully removes BDE-47 from several amended real-wastewater microcosms.
+The mixed YL-JM2C/JMP134 consortium removes BDE-47 from minimal salts medium, releases bromide during low-concentration BDE-47 degradation, and fully removes BDE-47 from several amended real-wastewater microcosms. In the direct comparison, both the mixed culture and YL-JM2C alone removed BDE-47 within 20 hours, but only the monoculture accumulated stoichiometric 2,4-DBP. The consortium therefore clears this intermediate as well as the parent. Pathway reconstruction and bromide release support catabolism, not an empirical closed carbon balance or demonstrated donor-feedback benefit.
@@ -889,7 +891,7 @@The main-text monoculture comparison and transwell experiment support diffusible intermediate cross-feeding. Parent disappearance occurs in YL-JM2C alone, while the partner prevents2,4-DBP accumulation. Current SYNTROPHY does not assert obligacy; the unresolved criterion is product-removal feedback making the donor metabolism more favourable. The demonstrated relay, functional enzymes, sequential growth and positive wastewater endpoints remain. They do not independently establish reciprocal fitness, return transfer of3,5-DBC or a closed carbon balance. Preserve the pre-existing image-panel curation task; this review did not inspect supplement pixels. Non-graph SYNTROPHIC_PARTNER roles remain for issue1753.
+ +Attaches to: ecological_interactions#YL-JM2C BDE-47 initiation, ecological_interactions#JMP134 2,4-dibromophenol conversion, ecological_interactions#Consortium BDE-47 removal without 2,4-DBP accumulation
when strain YL-JM2C was inoculated alone, BDE-47 disappeared within 20 h but accompanying by stoichiometric accumulation of 2,4-DBP.
+Main-text contrast distinguishes parent removal from clearance of the intermediate.
+this metabolic relay is mediated by cross-feeding of diffusible metabolites rather than direct physical contact.
+Transwell interpretation supports the positive cross-feeding relay, not reverse exchange or donor-feedback fitness.
+The PPOW SynCom was interpreted as a functionally complementary consortium in which R. opacus DSM 43250 drives long-chain C10-C28 alkane degradation while the two Pseudomonas members contribute aromatic catabolism and solvent-stress tolerance. The source leaves the exact mechanism unresolved, so this is modeled at community scope.
+HYPOTHESIZED: The PPOW SynCom was interpreted as a functionally complementary consortium in which R. opacus DSM 43250 drives long-chain C10-C28 alkane degradation while the two Pseudomonas members contribute aromatic catabolism and solvent-stress tolerance. The source leaves the exact mechanism unresolved, so this is modeled at community scope. Bulk removal and respiratory measurements are positive community observations, not direct member-resolved substrate allocation or metabolite exchange. The source also contradicts itself about abiotic and heat-killed controls, so the causal interpretation remains PARTIAL.
@@ -741,7 +741,7 @@Methods2.4 reports heat-killed controls and subtraction of abiotic removal, whereas the conclusion says these controls are lacking. Retain the reported positive bulk-removal result while flagging the unresolved source inconsistency; do not claim either adequately established control performance or complete control absence. The existing member-mechanism gap remains open, and inferred cross-feeding is not promoted to a directed edge. The abstract/main-text concentration-unit discrepancy is separately tracked under issue1753.
+ +Attaches to: ecological_interactions#PPOW aliphatic-aromatic division of labor
heat-killed controls were prepared by autoclaving the inoculum
+Methods2.4 says heat-killed controls were included; this conflicts with the conclusion.
+We acknowledge that this study lacks abiotic and heat-killed controls
+The conclusion contradicts Methods2.4; neither statement alone resolves actual control performance.
+