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Abstract: The filamentous fungus Metarhizium anisopliae is a well-characterized, arthropod pathogen used in the biological control of arthropod pests. Studies on the regulation of enzymes related to host infection such as proteases and chitinases have been reported but little is known about regulation of lipolytic enzymes in this fungus. Here we present the effects of different carbon sources such as components of the arthropod cuticle on the secretion of lipolytic enzymes by M. anisopliae. Differences in the induction of lipolytic activity were observed between the several carbon sources tested. Higher activities of lipase or lipase/esterase were found in culture media containing the arthropod integument components chitin and cholesteryl stearate. Several bands of lipolytic activity were also detected in zymograms, thus suggesting an important set of lipolytic enzymes secreted by the fungus. These results show that the fungus can modulate the secretion of lipolytic activity in response to host integument components, thus reinforcing the potential role of these enzymes during M. anisopliae infection. [Copyright &y& Elsevier]

Although Metarhizium anisopliae is one of the most studied fungal biocontrol agents, its infection mechanism is far from being completely understood. Using multidimensional protein identification technology (MudPIT), we evaluated the differential secretome of M. anisopliae E6 induced by the host Rhipicephalus microplus cuticle. The proteomic result showed changes in the expression of 194 proteins after exposure to host cuticle, such as proteins involved in adhesion, penetration, stress and fungal defense. Further, we performed a comparative genomic distribution of differentially expressed proteins of the M. anisopliae secretome against another arthropod pathogen, using the Beauveria bassiana ARSEF2860 protein repertory. Among 47 analyzed protein families, thirty were overexpressed in the M. anisopliae E6 predicted genome compared to B. bassiana. An in vivo toxicity assay using a Galleria mellonella model confirmed that the M. anisopliae E6 secretome was more toxic in cattle tick infections compared to other secretomes, including B. bassiana with cattle ticks and M. anisopliae E6 with the insect Dysdereus peruvianus , which our proteomic results had also suggested. These results help explain molecular aspects associated with host infection specificity due to genetic differences and gene expression control at the protein level in arthropod-pathogenic fungi. [ABSTRACT FROM AUTHOR]