Alkane-grown Beauveria bassiana: Mycelial pellets formation, oxidative stress induction and cell surface alterations

EDUARDO D. PRIETO; FLAVIA PAIXÃO; MARIANELA SANTANA; NICOLAS PEDRINI; CARLA HUARTE BONNET; JUAN PONCE

Congreso; 50th Annual Meeting and Golden Jubilee Celebration of the Society for Invertebrate Pathology; 2017

Entomopathogenic fungi attack insect hosts via attachment to the epicuticle,usually composed by aliphatic hydrocarbons. B. bassiana is able to grow oninsect-like alkanes improving its virulence. In this study we described somephysiological and molecular processes involved in fungal growth, nutritionalstress response and cell surface alterations found in alkane-grown conidia.Fungi were observed by transmission electron microscopy (TEM) and atomicforce microscopy (AFM), and their hydrophobicity was measured on the cellsurface. Additionally, the expression pattern of several genes associated withoxidative stress, hydrophobicity and peroxisomal biogenesis was analyzed byqPCR. We found a novel type of growth in alkane-cultured B. bassiana,similar to mycelial pellets described in other filamentous fungi grown inalkane-free media. Pellets were able to germinate in media without a carbonsource and produce viable conidia. TEM showed that pellets were formed byhyphae cumulates with an apparent surface thickening. Cell surfaceappeared to be more hydrophobic and exhibited different surfacetopographies as was observed by AFM. We also found a significant inductionin several genes encoding for catalases, superoxide dismutases,hydrophobins and peroxins. Additional studies are being conducted to betterunderstand the relationship between alkane growth adaptation and fungalcell changes, in order to improve the efficacy of fungal penetration throughthe cuticle and thus enhance virulence against insect pests.