Mixed Gallium LED Recovery Consortium

Community ID CommunityMech:000045

Ecological State ENGINEERED

Environment contaminated soil
ENVO:00002116

An engineered acidophilic microbial consortium specifically designed for recovering gallium from waste light-emitting diodes (LEDs) through non-contact bioleaching. This mixed community consists of three iron- and sulfur-oxidizing bacteria in equal proportions (1:1:1 ratio): Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans, and Leptospirillum ferrooxidans. The consortium produces biogenic lixiviants - primarily sulfuric acid (H₂SO₄) from sulfur oxidation and ferric iron (Fe³⁺) from iron oxidation - that solubilize gallium from GaN-based LED materials without direct contact between microbes and solid waste. Operating at pH 1.0-1.5 and 15 g/L pulp density, the system achieves exceptional 99.5% gallium leaching efficiency within just 3 days. The non-contact bioleaching approach separates the bioreactor (where microbes generate lixiviants) from the leaching reactor (where acids attack LED waste), preventing microbial inhibition by toxic LED components while enabling gallium recovery. In addition to gallium, the process recovers copper and nickel from LED substrates and interconnects. This biotechnological platform offers a sustainable alternative to harsh chemical leaching methods, utilizing microbial metabolism to extract critical materials from electronic waste while avoiding toxic emissions and reducing environmental impact.

Taxonomy

Taxon	Ontology ID	Functional Roles	Abundance
Acidithiobacillus thiooxidans	NCBITaxon:930	PRIMARY_DEGRADER PRIMARY_PRODUCER	ABUNDANT
PMID:31203122 - PARTIAL (IN_VITRO) "A novel step-wise indirect bioleaching process has been developed in this study for recycling valuable metals from WLEDs using adapted Acidithiobacillus ferrooxidans" doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO) "A. thiooxidans in the mixed bacterial community oxidizes the elemental sulfur to generate sulfuric acid, thereby decreasing the pH to 1.53."
Acidithiobacillus ferrooxidans	NCBITaxon:920	PRIMARY_PRODUCER PRIMARY_DEGRADER	ABUNDANT
PMID:30343816 - SUPPORT (IN_VITRO) "The adaptation of Acidithiobacillus ferrooxidans to LED powder was done through a serial acclimatisation procedure" doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO) "Non-contact bioleaching, utilizing cell-free biogenic lixiviant, attained 99.5 % Ga, 99.66 % Ni, and 71.2 % Cu recovery within 3 days."
Leptospirillum ferrooxidans	NCBITaxon:180	PRIMARY_PRODUCER PRIMARY_DEGRADER	ABUNDANT
PMID:31203122 - PARTIAL (IN_VITRO) "A novel step-wise indirect bioleaching process has been developed in this study for recycling valuable metals from WLEDs"

Ecological Interactions

Taxon

Cross-feeding

Mutualism

Syntrophy

Competition

Commensalism

Niche partitioning

Colonization facilitation

Strain competition

Predation

Biogenic Sulfuric Acid Production for Gallium Leaching

MUTUALISM

Source Taxon: Acidithiobacillus thiooxidans

Metabolites: sulfur (CHEBI:26833), sulfuric acid (CHEBI:26836), gallium(3+) (CHEBI:49631)

Biological Processes:

sulfur compound metabolic process (GO:0006790)

Evidence

PMID:31203122 - SUPPORT (IN_VITRO)

"At a pulp density of 20 g/L, the copper, nickel, and gallium recovery efficiency was 83%, 97%, 84%, respectively"
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO)

"Biological sulfuric acid can effectively dissolve the metallic gallium in WLEDs"

Ferric Iron Generation for Multi-Metal Recovery

CROSS_FEEDING

Source Taxon: Acidithiobacillus ferrooxidans

Target Taxon: Leptospirillum ferrooxidans

Metabolites: Fe(II) (CHEBI:29033), Fe(III) (CHEBI:29034), copper(2+) (CHEBI:29036), nickel(2+) (CHEBI:49786)

Biological Processes:

iron ion transport (GO:0006826)
carbon fixation (GO:0015977)

Evidence

PMID:31203122 - SUPPORT (IN_VITRO)

"The ferric ion concentration was controlled at 4-5 g/L with step-wise addition of biogenic ferric for faster bioleaching rate"

Synergistic Lixiviant Production in Mixed Consortium

MUTUALISM

Source Taxon: Acidithiobacillus thiooxidans

Target Taxon: Leptospirillum ferrooxidans

Metabolites: sulfuric acid (CHEBI:26836), Fe(III) (CHEBI:29034), gallium(3+) (CHEBI:49631)

Biological Processes:

sulfur compound metabolic process (GO:0006790)

Evidence

PMID:31203122 - PARTIAL (IN_VITRO)

"all metals' recovery improved with step-wise indirect bioleaching"
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO)

"Both sulfuric acid and ferric ions in the bioleaching agent contribute to gallium extraction from WLEDs"

Non-Contact Bioleaching System Design

COMMENSALISM

Source Taxon: Acidithiobacillus ferrooxidans

Metabolites: sulfuric acid (CHEBI:26836), Fe(III) (CHEBI:29034)

Evidence

PMID:31203122 - SUPPORT (IN_VITRO)

"A novel step-wise indirect bioleaching process has been developed in this study for recycling valuable metals from WLEDs using adapted Acidithiobacillus ferrooxidans"
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO)

"non-contact bioleaching could avoid the adverse effects of high concentration metal toxicity on microorganisms and completely recovered the Ga from WLEDs under the unfavorable condition of high iron concentration"

Environmental Factors

Factor	Value	Unit
Extreme Acidity for Gallium Dissolution	1.0-1.5	pH
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO) "A. thiooxidans in the mixed bacterial community oxidizes the elemental sulfur to generate sulfuric acid, thereby decreasing the pH to 1.53."
LED Waste Pulp Density	15	g/L
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO) "The biogenic lixiviants achieved a Ga leaching efficiency of 99.5 % in 15 g/L pulp density during 3 days of non-contact bioleaching."
Rapid Leaching Duration	3	days
doi:10.1016/j.jece.2025.120403 - SUPPORT (IN_VITRO) "In addition, the biogenic lixiviants prevented microbial toxicity caused by high pulp density and shortened the leaching time from 10 to 30 days to 3 days."
Mesophilic Temperature	~30	°C
doi:10.1016/j.jece.2025.120403 - WRONG_STATEMENT (IN_VITRO) "Results showed the significant promotion by bioelectricity on ammonium and total nitrogen by 7.80-8.14 %"
Publication Recency	2025	year
doi:10.1016/j.jece.2025.120403 - WRONG_STATEMENT (IN_VITRO) "Results showed the significant promotion by bioelectricity on ammonium and total nitrogen by 7.80-8.14 %"

Growth Media

biogenic lixiviant (A. thiooxidans/A. ferrooxidans/L. ferrooxidans 1:1:1 mixed culture)

pH 1.53

Preparation notes: Cell-free biogenic lixiviant generated by the mixed community and used for non-contact bioleaching of waste LEDs at 15 g/L pulp density; A. thiooxidans oxidizes elemental sulfur to sulfuric acid, lowering the pH to 1.53.

Evidence

doi:10.1016/j.jece.2025.120403

"A. thiooxidans in the mixed bacterial community oxidizes the elemental sulfur to generate sulfuric acid, thereby decreasing the pH to 1.53."

doi:10.1016/j.jece.2025.120403

"The biogenic lixiviants achieved a Ga leaching efficiency of 99.5 % in 15 g/L pulp density during 3 days of non-contact bioleaching."