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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 © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

Lipases secreted by Metarhizium anisopliae, an important biological control agent, could potentially be involved in the host infection process. Here, we present the activity profile during the host infection process and the effect of lipase activity inhibitor ebelactone B on infection. The previous treatment of spores with lipase activity inhibitor, ebelactone B, completely inhibited lipolytic activity and prevented the infection of the Rhipicephalus (Boophilus) microplus host. The results herein presented prove, for the first time, the importance of lipase activity in M. anisopliae host infection process. The filamentous fungus Metarhizium anisopliae is one of the most important and studied biological agents for the control of several arthropod pests, including the cattle tick Rhipicephalus (Boophilus) microplus. Lipases secreted by M. anisopliae could potentially be involved in the host infection process. This work presents the activity profile during the host infection process and the effect of lipase activity inhibitor ebelactone B on infection. During the course of tick exposure to spores (6-120 h) lipase activity increased from 0.03 ± 0.00 U to 0.312 ± 0.068 U using rho NP palmitate as substrate. In zymograms, bands of lipase activity were detected in ticks treated with spores without inhibitor. The previous treatment of spores with lipase activity inhibitor, ebelactone B, completely inhibited lipolytic activity, at all times specified, and prevented the infection of the R. microplus host. Spores treated with the inhibitor did not germinate on the tick, although this effect was not observed in the culture medium. The results herein presented prove, for the first time, the importance of lipase activity in M. anisopliae host infection process., (Copyright © 2009 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

Beauveria bassianas.l. is a cosmopolitan fungus used in the control of different species of arthropods. The current study explored the virulence for ticks, proteolytic and lipolytic activities of 10 BrazilianB. bassianas.l. isolates. For this purpose,Rhipicephalus microplusbiological parameters was evaluated after immersion of the engorged females in fungal suspension (108conidia mL−1) and the enzymatic activities were performed posteriorly the fungal growth in minimal medium. After the biological assays, five isolates changed all parameters analysed with highest efficacy of approximately 61% (CG 206) and 66% (CG 481). However, we observed that the most virulent isolates did not show the highest enzymatic activities. Interestingly, CG 500, considered an isolate of intermediate efficacy, demonstrated higher enzymatic activities than the other isolates in four of five analyses (total protease, Pr1, Pr2 and lipase;p < .05). Based on these data, it seems reasonable to suggest that these enzymatic activities should not be used as markers of virulence for these fungal isolates. It is noteworthy that complementary studies regarding chitinase analyses, gene expression, production of toxins and hydrophobicity of conidia can be used in the selection of pathogenic isolates. [ABSTRACT FROM PUBLISHER]

Abstract: Conidial contact with an arthropod surface is the first step of the fungal penetration and infection process. However, conidia of Metarhizium anisopliae have associated components, like enzymes that could be involved in triggering the penetration process and toxic effects that have not yet been well characterized. Fungi produce many enzymes that also are toxic components found in bacteria and animal venoms and thus may be considered as potential virulence factors. In this work, we report several enzymatic activities from spore surface protein extracts. The major proteolytic activities observed in spore surface proteins (SSP) were Pr1 and Pr2 activities, in that order. According to the zymograms obtained, SSP contain different proteases. SSP contain trehalase, exo- and endo-chitinase activities, and seven different chitinase bands which have been observed in zymograms. Activities involved in protection against reactive oxygen species (ROS) were also detected. Two lipolytic enzymes were also detected in lipase zymograms. Phospholipase C activity, closely related to microbial pathogenesis, was detected for the first time in M. anisopliae conidia. These activities described could be an initial step towards understanding the mechanisms involved in the first stage of M. anisopliae infection process and its toxic effects against arthropod hosts. [Copyright &y& Elsevier]