Microcoleus-Massilia Cyanosphere Urea Mutualism

Community ID CommunityMech:000157

Ecological State ENGINEERED

Environment soil biocrust
ENVO:01000910

A defined biological soil crust cyanosphere coculture pairing the pioneer cyanobacterium Microcoleus vaginatus PCC 9802 with the heterotrophic cyanosphere isolate Massilia sp. METH4. Across repeated studies of the same exact strain pair, M. vaginatus provides photosynthetically fixed organic carbon while the diazotrophic Massilia partner supports nitrogen acquisition through a specific carbon-for-nitrogen mutualism, including urea-mediated nitrogen transfer and GABA/glutamate signaling that organizes close spatial association.

Taxonomy

Taxon	Ontology ID	Functional Roles	Abundance
Microcoleus vaginatus PCC 9802	NCBITaxon:119532	PRIMARY_PRODUCER CROSS_FEEDER	DOMINANT
doi:10.1093/ismejo/wrad029 - SUPPORT (IN_VITRO) "Microcoleus vaginatus (PCC 9802), an axenic cyanobacterial strain isolated from biocrusts in the US southwest" doi:10.1093/ismejo/wrae246 - SUPPORT (IN_VITRO) "representative mutualist M. vaginatus PCC 9802 possesses genes for urea uptake"
Massilia sp. METH4	NCBITaxon:149698	SYNTROPHIC_PARTNER CROSS_FEEDER	COMMON
PMID:32968213 - SUPPORT (IN_VITRO) "Massilia sp. METH4" doi:10.1093/ismejo/wrae246 - SUPPORT (IN_VITRO) "mutualist Massilia sp. METH4"

Ecological Interactions

Taxon

Cross-feeding

Mutualism

Syntrophy

Competition

Commensalism

Niche partitioning

Colonization facilitation

Strain competition

Predation

Carbon-for-Nitrogen Resource Trading

MUTUALISM

Source Taxon: Microcoleus vaginatus PCC 9802

Target Taxon: Massilia sp. METH4

Metabolites: carbon dioxide (CHEBI:16526)

Biological Processes:

photosynthesis (GO:0015979)
biological process involved in interspecies interaction between organisms (GO:0044419)

Evidence

PMID:32968213 - SUPPORT (IN_VITRO)

"allowing for copious growth of both partners under nitrogen-free, organic C-free conditions"
PMID:32968213 - SUPPORT (IN_VITRO)

"indicating that M. vaginatus was the source of organic carbon needed to complete the C for N mutualism"

Urea-Mediated Nitrogen Transfer

CROSS_FEEDING

Source Taxon: Massilia sp. METH4

Target Taxon: Microcoleus vaginatus PCC 9802

Metabolites: urea (CHEBI:16199)

Biological Processes:

nitrogen fixation (GO:0009399)
biological process involved in interspecies interaction between organisms (GO:0044419)

Evidence

doi:10.1093/ismejo/wrae246 - SUPPORT (IN_VITRO)

"M. vaginatus and Massilia sp. METH4 in co-culture on N and C free media"
doi:10.1093/ismejo/wrae246 - SUPPORT (IN_VITRO)

"these results are consistent with the notion that urea is likely the vehicle for interspecies N transfer"

GABA and Glutamate Spatial Signaling

COLONIZATION_FACILITATION

Source Taxon: Massilia sp. METH4

Target Taxon: Microcoleus vaginatus PCC 9802

Metabolites: gamma-aminobutyric acid (CHEBI:16865), L-glutamic acid (CHEBI:16015)

Biological Processes:

chemotaxis (GO:0006935)
biological process involved in interspecies interaction between organisms (GO:0044419)

Evidence

doi:10.1093/ismejo/wrad029 - SUPPORT (IN_VITRO)

"the proximity of mutualistic diazotroph populations results in M. vaginatus bundle formation orchestrated through chemophobic and chemokinetic responses to gamma-aminobutyric acid (GABA) /glutamate (Glu) signals"
doi:10.1093/ismejo/wrad029 - SUPPORT (IN_VITRO)

"Glutamate, by contrast, was only produced in measurable quantities by M. vaginatus PCC 9802 and Massilia sp. METH4"

Associated Datasets

Dataset	Type	Repository	Accession
Exact-composition publication - Microcoleus vaginatus PCC 9802 and Massilia sp. METH4 nutrient exchange Primary publication establishing selective in vitro carbon-for-nitrogen exchange between M. vaginatus PCC 9802 and cyanosphere isolates including the exact M. vaginatus PCC 9802-Massilia sp. METH4 pair.	PHENOTYPE	OTHER	PMID:32968213
Exact-composition publication - Microcoleus vaginatus PCC 9802 and Massilia sp. METH4 GABA/Glu signaling Follow-up publication using the same exact pair while testing GABA/glutamate signaling and spatial organization of the cyanosphere mutualism.	PHENOTYPE	OTHER	doi:10.1093/ismejo/wrad029
Exact-composition publication - Microcoleus vaginatus PCC 9802 and Massilia sp. METH4 urea transfer Follow-up publication using the same exact pair for urea-related genome, expression, physiology, and nitrogen-transfer assays.	PHENOTYPE	OTHER	doi:10.1093/ismejo/wrae246
Biological soil crust cyanosphere context publication Contextual publication describing the natural M. vaginatus cyanosphere and nitrogen-fixing enrichment around M. vaginatus bundles; not treated as an exact-composition coculture publication.	AMPLICON_16S	OTHER	doi:10.1186/s40168-019-0661-2

Environmental Factors

Factor	Value	Unit
carbon and nitrogen limitation	carbon-free and nitrogen-free BG11-based coculture condition	N/A
PMID:32968213 - SUPPORT (IN_VITRO) "nitrogen-deplete (N−), carbon-free medium solid plates"
urea availability	low micromolar urea range tested as nitrogen source and transfer vehicle	N/A
doi:10.1093/ismejo/wrae246 - SUPPORT (IN_VITRO) "M. vaginatus PCC 9802 grows on urea down to the low micromolar range"
phototrophic incubation	23 C with white light and 14 h light/10 h dark cycle	N/A
doi:10.1093/ismejo/wrad029 - SUPPORT (IN_VITRO) "23°C, 18–20 μE m−2 s−1 of white light illumination and 14 h light/10 dark cycle"

Growth Media

BG11-based carbon- and nitrogen-limited coculture medium

Temperature 23 C

Atmosphere AEROBIC

Preparation notes: M. vaginatus PCC 9802 was maintained in 50% BG11 and shifted into nitrogen-limited BG11-based media; Massilia sp. METH4 was maintained on N-free Burks medium and paired with M. vaginatus under carbon- and nitrogen-free coculture conditions.

Evidence

doi:10.1093/ismejo/wrae246

"Axenic cyanobacterial cultures of M. vaginatus PCC 9802 and Synechocystis sp. PCC 6803 were maintained in 50% BG11 medium"

doi:10.1093/ismejo/wrae246

"The heterotrophic mutualists Arthrobacter sp. O80, Bacillus sp. O64, and Massilia sp. METH4, originally isolated from the cyanosphere of M. vaginatus"