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Optimal conditions for the microbial production of destruxins by Beauveria felina

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Author(s):
Raquel Peres de Morais Urano
Total Authors: 1
Document type: Doctoral Thesis
Press: São Carlos.
Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
Defense date:
Examining board members:
Roberto Gomes de Souza Berlinck; Emanuel Carrilho
Advisor: Roberto Gomes de Souza Berlinck
Abstract

The entomopathogenic fungus Beauveria felina produces destruxins, cyclic hexadepsipeptides which have several biological activities, such as insecticidal, phytotoxic, cytotoxic against tumor cells, antiviral activity against hepatitis B virus, among others. Because of the insecticidal activity of destruxins, fungi that produce them have a considerable economic importance. Therefore the aim of this study was to optimize the conditions for the growth of Beauveria felina and its production of destruxins by using different culture media, in order to isolate larger quantities for the evaluation of their toxic potential. Experimental design and multivariate analysis were used for the optimization of growth conditions, resulting in three conditions for optimum growth for each of the culture media MF, PDB and SBD. Both known and unknown destruxins were observed in each of the optimal conditions, along with destruxins that were not previously isolated from Beauveria felina. The cultivation of Beauveria felina in PDB was the one that showed the largest amount of unknown destruxins (5). We then carried out an optimization of the chromatographic analysis of destruxins by HPLC-PDA-ELSD-MS and the validation of this method. One of the fractions obtained from the culture medium of Beauveria felina showed anthelmintic activity against Haemonchus contortus, while two of its purified fractions, P1 (destruxin Ed1 - m/z 625 and pseudodestruxin B or pseudodestruxin C - isobaric m/z 669) and P7 (destruxin D or hydroxyhomodestruxin B or roseotoxin C - isobaric m/z 623), were active against the cattle tick Rhipicephalus microplus. (AU)