Transcriptomic profiling of Beauveria bassiana SAN01, an endophytic fungal entomopathogen, for the production of lignocellulosic enzymes

Beauveria bassiana, widely known for its ecological roles as an entomopathogen and as an endophyte, has recently been observed with a remarkable ability to utilize lignocellulosic biomass with the help of its active glycosyl hydrolases and other accessory enzymes. Hence, the capability of the fungus to produce different lignocellulosic biomass degrading enzymes was demonstrated quantitatively in this study. Furthermore, the transcriptional responses of B. bassiana during lignocellulose degradation in comparison with its well-studied endophytic condition were elucidated by comparative genome-wide transcriptomics using the NextSeq 550 system. The B. bassiana strain was recorded to produce enzymes including amylases, cellulases, glucanases, pectinases as well as various lignin and xylan degrading enzymes at significant levels ranging from 126.12 +/- 7.71 U/L (laccase) to 295.42 +/- 12.65 U/mL (xylanase). Subsequently, a clear molecular distinction was shown under the different tropic states as 458, 521 and 497 genes were found to be differently expressed in the fungus between the fermentation vs endophytic, fermentation vs control and endophytic vs control groups, respectively. The Carbohydrate Active Enzyme (CAZy) annotation of the transcriptome under fermentation conditions also showed the upregulation of many carbohydrases that were determined quantitatively earlier in the study. This study thus highlights the adaptive plasticity of B. bassiana for the deconstruction of plant biomass with the aim of enhancing its alternative industrial applications, especially in the production of biomass-degrading enzymes for biofuel production.