A defined algal-bacterial coculture in which Chlorella minutissima was grown with Escherichia coli in airlift reactors under mixotrophic glucose, glycerol, and acetate conditions. The coculture produced more algal biomass, consumed more carbon substrate, and increased lipid and starch productivity relative to axenic algal cultures. This system is relevant to DOE-aligned algal biofuel biotechnology because it tests whether bacterial contamination or partnership can improve production of algal biofuel precursors rather than suppressing algal biomass.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Chlorella minutissima — ontology label: Chlorella | NCBITaxon:3071 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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ABUNDANT |
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| Escherichia coli | NCBITaxon:562 · TaxonMech · TraitMech |
CROSS_FEEDER
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ABUNDANT |
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
Bacterial Enhancement of Algal Biomass
MUTUALISMPARTIAL - in five-day separate-substrate assays, the alga reported as C. minutissima UTEX 2341 had 200-587% greater qPCR-partitioned biomass productivity at 10 g/L substrate with E. coli ATCC 25922. Higher bacterial viable CFU at 96 hours supports a mutualism interpretation, not bacterial neutrality; bacterial total dry biomass was not uniformly enhanced. Benefits were concentration-dependent, and exact mediators were not isolated.
Source Taxon: Escherichia coli
Target Taxon: Chlorella minutissima
Metabolites: D-glucose (CHEBI:4167 · MediaIngredientMech · CMMMech), glycerol (CHEBI:17754 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
PARTIAL - greater algal biomass can increase volumetric lipid and starch yield. The bulk product assays include both partners, and kanamycin suppressed starch in axenic glucose controls; biomass enhancement does not establish that every product-content difference is bacteria-mediated.
Evidence
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PMID:24805253 - PARTIAL (IN_VITRO)"grew more rapidly and to higher densities in the presence of E. coli"
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PMID:24805253 - SUPPORT (IN_VITRO)"produced 200-587% more algal biomass than the axenic C. minutissima cultures"
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PMID:24805253 - PARTIAL (IN_VITRO)"viable cell counts at 96 hours at 10 g/L substrate were 51, 1600, and 6400 times higher in co-cultures"
Enhanced Mixotrophic Carbon Substrate Consumption
At 10 g/L initial glucose, glycerol or acetate, five-day cocultures consumed 23-737% more bulk substrate than the summed monocultures. Lower-dose depletion limits that comparison. This is community-level substrate disappearance, not measured algal-to-bacterial carbon transfer.
Participating Taxa: Chlorella minutissima, Escherichia coli
Metabolites: D-glucose (CHEBI:4167 · MediaIngredientMech · CMMMech), glycerol (CHEBI:17754 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
Biological Processes:
- carbohydrate metabolic process (GO:0005975 · PathwayMech)
HYPOTHESIZED - additional consumed substrate could supply carbon for increased lipid and starch production. Bulk uptake and product measurements do not trace carbon into either partner or separate this contribution from altered biomass and antibiotic-sensitive starch accumulation.
Evidence
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PMID:24805253 - SUPPORT (IN_VITRO)"consumed 23-737% more of the available carbon substrate"
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PMID:24805253 - SUPPORT (IN_VITRO)"than the sum of substrate consumed by E. coli and C. minutissima alone"
Increased Biofuel-Precursor Productivity
At 10 g/L substrate, bulk coculture lipid and starch productivities exceeded axenic algal controls. These are combined-biomass endpoints, not reciprocal fitness measurements. In separate glucose controls, kanamycin suppressed starch at 10 g/L; untreated axenic algae had starch content comparable to cocultures. The product-content difference is therefore not wholly attributable to E. coli, although biomass and lipid benefits remain supported.
Metabolites: lipid (CHEBI:18059 · MediaIngredientMech · CMMMech), starch (CHEBI:28017 · MediaIngredientMech · CMMMech)
Biological Processes:
- lipid metabolic process (GO:0006629 · PathwayMech)
- starch metabolic process (GO:0005982 · PathwayMech)
Evidence
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PMID:24805253 - SUPPORT (IN_VITRO)"total lipid and starch productivity were elevated in co-cultures compared to axenic cultures"
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PMID:24805253 - SUPPORT (IN_VITRO)"bacterial contamination was not detrimental to the production of biofuel precursors"
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PMID:24805253 - SUPPORT (IN_VITRO)"kanamycin appeared to significantly suppress starch levels"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
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Chlorella-Ecoli mixotrophic biofuel precursor publication
PubMed and PMC-indexed PLOS ONE study reporting algal biomass, substrate consumption, lipid, starch, biofouling, and acid-formation phenotypes for Chlorella minutissima and E. coli cocultures. |
PHENOTYPE | OTHER | PMID:24805253 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which partner-resolved transfers mediate growth, and how much product change persists with matched controls?
Gas, vitamin/hormone and organic-carbon exchange remain candidate mechanisms, not measured fluxes. Viable CFU and total bacterial biomass differ. Carbon tracing and matched antibiotic controls across substrates are needed to partition product effects. UTEX 2341 legacy identity is a separate grounding followup (#1300); the existing canonical taxon is not reverified here.
Attaches to: ecological_interactions#Bacterial Enhancement of Algal Biomass, ecological_interactions#Enhanced Mixotrophic Carbon Substrate Consumption, ecological_interactions#Increased Biofuel-Precursor Productivity
Environmental Factors
| Factor | Value | Unit |
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| Mixotrophic carbon substrates | glucose, glycerol, and acetate | N/A |
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| Initial substrate concentration | 1% | N/A |
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| Scale-up constraints | biofouling and acid formation | N/A |
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Growth Media
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