Titulo en ingles: Analysis of polyhydroxyalkanoate synthases ( PhaC1 and PhaC2 ) in a strain of Pseudomonas fluorescens IBUN S1602 isolated from Colombian soil. Resumen La cepa Pseudomonas fluorescens IBUN S1602 conforma el grupo de aislamientos provenientes de suelos colombianos de cana de azucar, que acumula polihidrioxialcanoato (PHA), fue seleccionada como promisoria para escalamiento comercial por tener afinidad por sustratos alternativos y economicos como el glicerol, aceites usados, suero de leche, entre otros. Dada la importancia de la enzima sintasa en la sintesis de los PHAs, en el presente trabajo se realizo el analisis molecular de los genes phaC1 y phaC2 que codifican las enzimas sintasas tipo II (PhaC1 y PhaC2) . Para la obtencion de los amplimeros requeridos en la secuenciacion, se utilizo la tecnica de PCR bajo condiciones estandarizadas para iniciadores disenados reportados en las bases de datos. Se identificaron dos fragmentos de 1680 pb y 1683 pb correspondientes a phaC1 y phaC2. El analisis comparativo de las secuencias proteicas resultantes de estos genes demuestra que la sintasa IBUN S1602 contiene la region α/β hidrolasa y 8 residuos de aminoacidos conservados, que son caracteristicas de las sintasas examinadas a nivel mundial. Se analizo la estructura enzimatica a nivel primario y se predijo la secundaria. Se concluyo que las sintasas de la cepa Pseudomonas fluorescens IBUN S1602 presentan alta homologia con las sintasas tipo II que se reportan para Pseudomonas . Los resultados obtenidos contribuyen al entendimiento basico de la biosintesis de PHA, la cual permitira, en un futuro, el aumento de la calidad de PHA debida a la modulacion del nivel de sintasa que se exprese en un organismo recombinante, con el fin de variar el peso molecular del biopolimero, propiedad esencial en el estudio de aplicaciones industriales. Palabras clave: polihidroxialcanoatos, PHA sintasa, bioinformatica, biopolimero, PhaC1, PhaC2. Abstract The strain Pseudomonas fluorescens IBUN S1602 forms the group of isolates from colombian sugarcane soil´s , which accumulates polyhydroxyalkanoate biopolymer (PHA) and was selected as promising for commercial scale by having affinity for economic and alternative substrates such as glycerol, oils, whey, among others. Given the importance of the synthase enzyme in the synthesis of PHAs, was realized the molecular analysis of genes phaC1 and phaC2 which encode type II synthases (PhaC1 y PhaC2). To obtain the amplimers required in the sequencing, was used the PCR technique under standardized conditions for primers designed based on the updated review in databases. Were identified two fragments of 1680 bp and 1683 bp for phaC1 and phaC2. Comparative analysis of the resulting protein sequences of these genes show s that the IBUN S1602 synthases containing the region α / β hydrolase and 8 conserved amino acid residues that are characteristic of synthases examined worldwide. Enzyme structure was analyzed at the primary level and was predicted the secondary. It is concluded that synthase strain Pseudomonas fluorescens IBUN S1602 has high homology with type II synthases that are reported for Pseudomonas . The results contribute to basic understanding of the biosynthesis of PHA, and will allow in the future, increasing the quality of PHA due to modulation of the level of synthase is expressed in a recombinant organism, in order to vary the weight molecular biopolymer, an essential property in the study of industrial applications. Keywords: polyhydroxyalkanaotes, PHA synthase, bioinformatics, biopolymer, PhaC1, PhaC2.