Caracterização molecular de xanthomonas campestris pv. Pruni pela técnica de RAPD e prognóstico da produção e qualidade da xantana

Abstract

Several Xanthomonas campestris strains are able to produce an extracellular biopolymer called xanthan gum, that has been used in a wide variety of foods. The xanthan used in Brazil is, in its totality, imported. However, the Brazilian microbiota is very rich, presenting good potential for the production of this polymer. The random amplified polymorphic DNA technique (RAPD) presents a series of practical advantages when compared with others DNA techniques. The objective of this work was to correlate the genetic profile produced by RAPD technique with host, yield, viscosity and chemical composition of the biopolymers synthesized by 20 strains of Xanthomonas campestris pv. pruni. For RAPD analyzis, two primers were utilized, resulting in polymorphic amplified fragments, allowin the strains to be differentiated. The fermentation was done in PMII, at 28oC and 200 rpm for 72 h and the viscosity of the aqueous solution at 3% was analyzed at 25oC in HAAKE RS150 rheometer. For analyzis of chemical composition the comparative thin layer chromatography was used. Xanthan yield in PMII medium were not uniform and varied according with the X. campestris pv. pruni strain. All the biopolymers showed pseudoplastic behavior and all the strains studied had mannose, glucose and glucuronic acid. The RAPD profile showed a large similarity among the strains. With the tested primers, it was not possible to correlate RAPD X yield X viscosity X chemical composition. It was observed difference between the genetic profile of a strain from almond tree and strains from plum and peach trees.