Biochemical characterization of a trypanosomatid isolated from the plant Amaranthus retroflexus

A protozoan flagelate has recently been isolated from Amaranthus retroflexu s. This plant grows near economically important crops in southeastern Spain , which are known to be parasitized by Phytomonas spp. The present study fo cuses on the characterization of the energy metabolism of this new isolate. These flagellates utilize glucose efficiently, as their primary energy sou rce, although they are unable to completely degrade it. They excrete ethano l, acetate, glycine, and succinate in lower amount, as well as ammonium. Th e presence of glycosomes was indicated by the early enzymes of the glycolyt ic pathway, one enzyme of the glycerol pathway (glycerol kinase), and malat e dehydrogenase. No evidence of a fully functional citric-acid cycle was fo und. III the absence of catalase activity, these flagellates showed signifi cant superoxide dismutase activity located in the glycosomal and cytosolic fractions. These trypanosomes, despite being morphologically and metabolica lly similar to other Phytomonas isolated from the same area, showed signifi cant differences, suggesting that they are phylogenetically different speci es.