Fungi have long been recognized as prolific producers of diverse secondary metabolites, many of which serve as important leads for pharmaceutical and agricultural applications. However, genomic analyses have revealed that numerous biosynthetic gene clusters remain transcriptionally silent, or “dormant,” under standard laboratory conditions. Activation of these dormant genes has therefore become a key strategy for the discovery of novel metabolites with unique chemical and biological properties.  Co-cultivation has emerged as an effective approach to awaken silent biosynthetic pathways. Previous studies have shown that Tsukamurella pulmonis, a mycolic acid–containing bacterium, can activate dormant genes in actinomycetes. In this study, we focused on Mycobacterium smegmatis, another mycolic acid–containing bacterium, as a potential microbial activator of fungal secondary metabolism. Co-cultivation experiments with marine-derived fungi maintained in our laboratory revealed that Aspergillus niger selectively produced the cyclic peptide Malformin C and the γ-pyrone derivative Desmethylkotanin under co-culture conditions. Furthermore, Paecilomyces formosus, a fungus with limited prior reports of secondary metabolites, produced phenylpropanoid and coumarin derivatives specifically during co-cultivation. These compounds were not detected when M. smegmatis cells were heat-killed by autoclaving, suggesting that a direct interaction mediated by viable bacterial cells is essential for the induction.  This presentation will highlight these findings and demonstrate the potential of Mycobacterium smegmatis as an effective microbial partner for activating dormant fungal biosynthetic genes and enhancing secondary metabolite diversity.