Synthetic Periphyton Freshwater Biofilm

Sphingomonas elodea was used to condition the colonization surface with an EPS-rich attachment layer before phototroph assembly. The source attributes a sticky attachment function to that layer. PARTIAL: the reviewed main text does not isolate its effect size in an EPS-free comparison or establish persistence of the conditioning bacterium. Sphingomonas is not an added canonical member of this record's aggregate phototroph taxonomy.

Biological Processes:

• biofilm formation (GO:0042710 · PathwayMech)

Evidence

• PMID:35869094 - SUPPORT (IN_VITRO)
  "Groups were added sequentially onto growth chambers covered with the EPS-producing bacteria Sphingomonas elodea "
• PMID:35869094 - PARTIAL (IN_VITRO)
  "This bacterium provided a solid and sticky attachment layer for the subsequently introduced phototrophic species "

The two group-A diatoms showed predominantly surface-attached growth at the selected early time point, covering only part of the conditioned surface. This is a diatom-subset attachment outcome; leaving unoccupied area is not evidence that these diatoms facilitated later phototrophs. The canonical diatom descriptor represents this selected subset.

Participating Taxa: diatoms

Biological Processes:

• biofilm formation (GO:0042710 · PathwayMech)

Evidence

• PMID:35869094 - SUPPORT (IN_VITRO)
  "the large majority of cells (approximately 6 to 7 times more cells than in the supernatant) were attached to the substrate surface"

After group B joined group A, the combined diatom biofilm showed predominantly attached cells, greater surface coverage and a more heterogeneous architecture at the selected AB observation point. Later incubation increased detached cells and reduced PSII yield. These are combined-group time-course observations, not an isolated demonstration of facilitation by one diatom group or niche partitioning.

Participating Taxa: diatoms

Biological Processes:

• biofilm formation (GO:0042710 · PathwayMech)

Evidence

• PMID:35869094 - SUPPORT (IN_VITRO)
  "14 days after group B was added to group A, most of the cells were attached"
• PMID:35869094 - SUPPORT (IN_VITRO)
  "Longer incubation, on the other hand, led to an increase of detached cells"

The mature ABC periphyton showed broad surface attachment, high density and relatively high PSII yield at the measured endpoint. Although 26 phototrophic species were introduced, the mature community contained at least 22 detected species and three introduced species were no longer detected. This is a community establishment outcome, not proof that all input members persisted or that assembly order caused ecological facilitation.

Biological Processes:

• biofilm formation (GO:0042710 · PathwayMech)
• photosynthesis, light reaction (GO:0019684 · PathwayMech)

Evidence

• PMID:35869094 - SUPPORT (IN_VITRO)
  "we obtained a stable benthic community after a total colonization duration of 30 days "
• PMID:35869094 - SUPPORT (IN_VITRO)
  "a diverse and complex mature periphyton composed of at least 22 different phototrophic species"
• PMID:35869094 - SUPPORT (IN_VITRO)
  "three species were no longer detected in the mature periphyton"

Independent assemblies reproduced community composition and physical structure. Warming and terbuthylazine altered taxon abundances and reduced biofilm structure and biomass in the reported comparisons. PSII quantum yield was generally similar across treatments, with the reported highest-herbicide exception at the AB stage. Preserved PSII is consistent with, but does not demonstrate, functional redundancy. Neither reproducibility nor these stress phenotypes establishes NICHE_PARTITIONING.

Biological Processes:

• biofilm formation (GO:0042710 · PathwayMech)
• photosynthesis, light reaction (GO:0019684 · PathwayMech)

Evidence

• PMID:35869094 - SUPPORT (IN_VITRO)
  "we were able to obtain a reproducible and diverse synthetic community "
• PMID:35869094 - SUPPORT (IN_VITRO)
  "increased temperature and exposure to the herbicide terbuthylazine affected negatively the 3D-structure and biomass but not the PSII quantum yield "
• PMID:35869094 - SUPPORT (IN_VITRO)
  "except for periphyton exposed to 100 nM terbuthylazine at 18 days"
• PMID:35869094 - PARTIAL (IN_VITRO)
  "further specifically designed studies are needed to clearly demonstrate functional redundancy"