ABSTRACT
Recombinant DNA technologies enable the direct isolation and expression of novel genes from biotopes containing complex consortia of uncultured microorganisms. In this study, genomic libraries were constructed from microbial DNA isolated from insect intestinal tracts from the orders Isoptera (termites) and Lepidoptera (moths). Using a targeted functional assay, these environmental DNA libraries were screened for genes that encode proteins with xylanase activity. Several novel xylanase enzymes with unusual primary sequences and novel domains of unknown function were discovered. Phylogenetic analysis demonstrated remarkable distance between the sequences of these enzymes and other known xylanases. Biochemical analysis confirmed that these enzymes are true xylanases, which catalyze the hydrolysis of a variety of substituted beta-1,4-linked xylose oligomeric and polymeric substrates and produce unique hydrolysis products. From detailed polyacrylamide carbohydrate electrophoresis analysis of substrate cleavage patterns, the xylan polymer binding sites of these enzymes are proposed.
Subject(s)
Bacteria/enzymology , Digestive System/microbiology , Endo-1,4-beta Xylanases/genetics , Endo-1,4-beta Xylanases/metabolism , Fungi/enzymology , Isoptera/microbiology , Moths/microbiology , Amino Acid Sequence , Animals , Bacteria/genetics , DNA, Bacterial/analysis , DNA, Bacterial/isolation & purification , DNA, Fungal/analysis , DNA, Fungal/isolation & purification , Endo-1,4-beta Xylanases/chemistry , Endo-1,4-beta Xylanases/classification , Fungi/genetics , Gene Library , Molecular Sequence Data , Phylogeny , Sequence AlignmentABSTRACT
Presentamos una revisión literaria sucinta, histórica, científica y aplicada, de las soluciones empleadas en la Terapia de Rehidratación Oral (TRO) diseñada por la Organización Mundial de la Salud (OMS) para el manejo de las Enfermedades Diarreicas (ED) de la infancia
