Cocultivation and pH shape the metabolite profile of Chaetomium globosum SCF-24: insights from gas chromatography-mass spectrometry analysis.

This study investigated the effects of cocultivation and pH on the metabolite profile of Chaetomium globosum SCF-24. Axenic and coculture fermentation systems were established at pH 5-8, and resulting extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). A hierarchical clustered heatmap was used to compare metabolite profiles based on presence-absence data. GC-MS detected 51 putatively identified primary and secondary metabolites, some of which were detected across all treatments, whereas others were condition-specific. Metabolite profiles also differed between axenic cultures and cocultures, even at identical pH, with numerous metabolites detected exclusively in cocultures, demonstrating that microbial interactions influenced metabolite profiles beyond the effects of pH. Antibacterial assays showed that only extracts from axenic cultures and cocultures at pH 6 inhibited both Gram-positive and Gram-negative test bacteria. Notably, treatments with similar metabolite profiles did not exhibit comparable antibacterial activity, and the treatment with the highest number of detected metabolites was not the most bioactive, suggesting that bioactivity depends more on metabolite composition than on the number of detected metabolites. Overall, these findings demonstrate the combined influence of biotic and abiotic cultivation factors on metabolite composition and associated antibacterial activity.