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Selection of Metarhizium anisopliae for extracellular enzyme production and virulence toward Triatoma infestans

José Carlos da Silva^I; José Pinto de Siqueira Júnior^I; Carlos Brisola Marcondes^II

Departamento de Biologia Molecular/CCEN and ²Núcleo de Medicina Tropical/CCS, Universidade Federal da Paraiba, 58.059 Jo^go Pessoa, PB, Brasil. Send correspondence to J.C.S.

ABSTRACT

Recurrent mutation and selection have been used to increase the production of the extracellular enzymes amylase, lipase and protease by the entomopathogenic fungus Metarhizium anisopliae. A selection program was initiated from strain E₉ and continued through two cycles of mutation and selection. 8-Methoxypsoralen plus near ultraviolet light were used as mutagen and enzyme production was estimated semiquantitatively by the enzymatic index. Isolates with high enzymatic indices were tested for virulence toward 3rd-instar nymphs of Triatoma infestans. Isolates selected for amylase and lipase showed greater virulence than the original strain, while the virulence of isolates selected for protease was equal to, or lower than that of the original strain.

Keywords: selection; Metarhizium anisopliae; virulence; Triatoma infestans.

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