Maize SC2 Root-Rot Biocontrol SynCom

The three-member SC2 inhibited Pythium torulosum radial growth on PDA after seven days, comparably to C7. In a separate growth-chamber experiment, SC2-treated B73 seedlings challenged with Pythium had improved height and fresh root biomass at 14 days. These positive antagonist and protection phenotypes do not isolate nutrient competition, secreted antimicrobials or host immune activation. The three canonical bacterial terms identify the curated SC2 roster; Pythium is an external challenge organism, not an inoculum member. Exact strain-number and ZK-alias mapping is preserved, not independently recertified.

Participating Taxa: Enterobacter cloacae S4, Stenotrophomonas maltophilia S1, Chryseobacterium indologenes S5, Pythium torulosum

Evidence

• PMID:42039819 - SUPPORT (IN_VITRO)
  "All sub-communities displayed inhibition comparable to that of the established biocontrol community C7"
• PMID:42039819 - SUPPORT (IN_VIVO)
  "Among the sub-communities tested, SC1 (comprising strains S4, S6, and S7) and SC2 (comprising strains S4, S1, and S5) consistently showed enhanced protection from the pathogen and promoted plant growth traits significantly more than both the non-inoculated control and the C7 community."

SC2 seed treatment improved B73 maize height and fresh root biomass after 14 days in Pythium-infested potting mix relative to the challenged comparison treatments, with SC1 and SC2 outperforming C7 in the reported experiment. These are treatment-level plant benefits, not reciprocal bacterial benefit, field yield or proof of IAA-mediated protection. Zea mays is an external host, not a fourth bacterial inoculum member. The candidate IAA mechanism derives from a separate culture assay, not a measured plant hormone pool or traced bacterial-to-host delivery.

Participating Taxa: Enterobacter cloacae S4, Stenotrophomonas maltophilia S1, Chryseobacterium indologenes S5, Zea mays

Metabolites: indole-3-acetic acid (CHEBI:16411 · MediaIngredientMech · CMMMech)

Biological Processes:

• plant growth (GO:0040007 · PathwayMech)

Evidence

• PMID:42039819 - SUPPORT (IN_VIVO)
  "Among the sub-communities tested, SC1 (comprising strains S4, S6, and S7) and SC2 (comprising strains S4, S1, and S5) consistently showed enhanced protection from the pathogen and promoted plant growth traits significantly more than both the non-inoculated control and the C7 community."

SC2 culture supernatants gave Salkowski estimates of approximately 45 ug/mL at day 2 and 65 ug/mL at day 7 against a pure-IAA calibration, highest among the tested C7-derived communities. CAS agar activity was reported as a 0.50 cm halo at day 7 (p=0.015 versus control). Retain the authors auxin and siderophore interpretation at assay scope: these colorimetric and halo measurements do not resolve molecular identities, biosynthetic pathways, member-specific contributions, plant delivery or reciprocal mutualism. They were not selective mediator perturbations of the plant or pathogen assays.

Participating Taxa: Enterobacter cloacae S4, Stenotrophomonas maltophilia S1, Chryseobacterium indologenes S5

Metabolites: indole-3-acetic acid (CHEBI:16411 · MediaIngredientMech · CMMMech), siderophore (CHEBI:26672 · MediaIngredientMech · CMMMech)

Evidence

• PMID:42039819 - SUPPORT (IN_VITRO)
  "SC2 exhibited the highest IAA levels, reaching ∼45 μg/mL by day 2 and ∼65 μg/mL by day 7, indicating strong and sustained auxin synthesis."
• PMID:42039819 - SUPPORT (IN_VITRO)
  "siderophore activity ( Figure 7B ) was most pronounced in SC1 (0.55 cm, p = 0.01) and SC2 (0.50 cm, p = 0.015), followed by C7 (0.45 cm, p = 0.02)."