Characterization and carbon metabolism in fungi pathogenic to Chagas disease vectors.

JUAREZ, M.P.; CRESPO, R.; CALDERÓN F, G; LECUONA, R.; CAFERATTA L.F.R.

Brasil

Congreso; XXI International Congreso of Entomology.; 2000

In this paper we report the pathogenicity of Beauveria bassiana isolates to Triatoma infestans, the vector of Chagas disease in Argentina. A 100% mortality was achieved with mean lethal times varying from 7.7 to 11.1 days. Degradation of their insect host epicuticular hydrocarbons was previously shown to be a major metabolic pathway for energy provision (Napolitano R. and M. P. Juárez. 1997. Arch. Biochem. Biophys. 344: 208-214). The unsaturated/saturated ratio for fungal fatty acids was markedly diminished for alkane-grown cells, in addition, the composition of the saturated fraction was modified showing large amounts of heptacosanoic and  eicosanoic acids, together with heptadecenoic acid in the unsaturated fraction. The hydrocarbon profile of B. bassiana showed a saturated chain length distribution, with a marked prevalence for straight chains, ranging from C18 to C37 in the carbon squeleton. Alkane-grown cells showed a homogenous distribution of their hydrocarbon fraction, with a similar ratio for odd/even chains. After 48 hr-incubation assays, carbon metabolism from [1-14C]acetate was largely diminished following a period of alkane-growth induction; glucose-grown cells readily incorporated 19% of the label into fungal lipids, incorporation was reduced to 5.3% for alkane-grown cells. These data provide evidence towards the potential of improving current biocontrol agents performance by modification of the supplemented carbon source.    Index terms: Beauveria bassiana, Triatoma infestans, hydrocarbon catabolism, fatty acids.