Cultivation-dependent transcriptomic reprogramming and insecticidal performance of Beauveria bassiana A1 from solid-state and submerged cultures

Background Beauveria bassiana is an important entomopathogenic fungus widely used in microbial pest management. Solid-state fermentation (SSF) is the predominant production method, whereas submerged liquid fermentation (SLF) offers potential advantages in process control and scalability. However, how cultivation conditions affect fungal transcriptional programs and the insecticidal performance of the resulting spores remains insufficiently understood. This study compared the transcriptomic profiles and insecticidal efficacy of B. bassiana A1 produced by SSF and SLF against the diamondback moth, Plutella xylostella . Results Transcriptomic analysis with a false discovery rate (FDR) < 0.05 revealed pronounced transcriptional divergence between solid-state (A1-S) and submerged (A1-L) cultures. A1-S showed higher expression of genes associated with secondary metabolism and extracellular degradation, including all differentially expressed PKSs (4/4), most NRPSs (6/8), hydrolases (112/168), proteases (52/89), and chitinases (5/7). The cuticle-degrading subtilisin-like protease bassiasin I (BBA_00443) was 32.4-fold higher in A1-S (FDR = 2.10×10⁻¹⁶). In contrast, A1-L preferentially expressed iron-acquisition and selected host-interaction-associated genes. Bioassays demonstrated concentration-dependent mortality for both spore types. At 10⁷ spores/mL, A1-S showed a tendency toward faster early mortality, but the difference from A1-L was not statistically significant after Benjamini–Hochberg adjustment (P = 0.08814). At 10⁸ spores/mL, both spore types achieved 100% mortality by day 3, with no significant difference between them (P = 0.83504). Conclusion Cultivation conditions induced substantial transcriptomic reprogramming in B. bassiana A1, particularly in extracellular degradation and secondary metabolism. These differences were associated with differences in the timing of host mortality rather than ultimate insecticidal efficacy. The ability of submerged conidia to achieve comparable mortality at high propagule density supports further evaluation of SLF as an alternative production platform for B. bassiana biopesticides, particularly when formulation and application strategies are optimized to compensate for differences in early infection dynamics.