Production of mycelial pellets by alkane-grown Beauveria bassiana display oxidative stress and cell surface alterations

C. HUARTE-BONNET; F.R.S. DA PAIXAO; N. PEDRINI

Simposio; International symposium of fungal stress 2017; 2017

B. bassiana is able to grow on insect-like hydrocarbons improving its virulence. In this study we described the physiological and molecular processes involved in fungal growth, nutritional stress response and cell surface alterations found in alkane-grown conidia. Fungi were observed by optical microscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM), and their hydrophobicity was measured on the cell surface. Additionally, the expression pattern of several genes associated with oxidative stress, hydrophobicity and peroxisomal biogenesis was analyzed by qPCR.We found a novel type of growth in alkane-cultured B. bassiana, similar to mycelial pellets described in other alkane-free fungi, which were able to germinate in media without a carbon source. Optical microscopy and TEM showed that pellets were formed by hyphae cumulates with an apparent surface thickening. Cell surface appeared to be more hydrophobic and exhibited different surface topographies as was observed by AFM. We also found a significant induction in several genes encoding for catalases, superoxide dismutases, hydrophobins and peroxins.Additional studies are being conducted to better understand the relationship between alkane growth adaptation and fungal cell changes, in order to improve the efficacy of fungal penetration through the cuticle and thus enhance virulence against insect pests.