In silico interactome analysis reveals distinct and complementary metabolic roles of bacteria in stingless bee larval food.

Background: Observational studies in vinegar fermentation suggested a temporal succession between Bacillus cereus and Acetilactobacillus jinshanensis. Here, we reinterpret this pattern in terms of facilitation and niche construction rather than classical competitive succession. We test this ecological model in a distinct biological context - stingless bee larval food - by combining organism-specific interactomes (GenPPI), hub topology (BriCe outliers), and genome-scale metabolic modeling. Results: The B. cereus interactome shows a diversified hub architecture enriched in environmental sensing, transport, stress response, and secreted effectors-consistent with a pioneer that probes and actively modifies a fresh niche. In contrast, the A. jinshanensis interactome is dominated by a cytoplasm-centric, translation-heavy super-hub-consistent with a fast-growth specialist optimized for efficient biomass production once resources are simplified and available. Flux analyses indicate capacities for xenobiotic processing and terpenoid precursor synthesis in both organisms, but the topological signatures and pathway enrichments align with complementary roles: niche construction and conditioning by B. cereus, followed by rapid exploitation by A. jinshanensis. conclusion: Our findings support a facilitation-based ecological mechanism: B. cereus functions as an early colonizer and niche engineer-sensing, detoxifying, and depolymerizing complex substrates via secreted enzymes-while A. jinshanensis is a fast-growth specialist whose dominance emerges in the conditioned niche. This reframing resolves the apparent contradiction between a "fast-growth" profile and late-stage dominance and provides mechanistic, systems-level support for complementary roles across distinct environments.