Construction of mutant gene exoz involved in the synthesis of repeating subunits of EPS and the genes phbA, phbB and phbC responsible for the synthesis of PHB in Rhizobium tropici SEMIA 4080

Abstract

Previous work (Proc. FAPESP 01/05720-4 and 05/53170-4) allowed to verify differences in the compositions of exopolysaccharides (EPS) produced by 26 strains of rhizobia patterns, and analyze polysaccharides required for nodulation of beans. The species of nitrogen fixing bacteria belonging to the families Rhizobiaceae and Phyllobacteriaceae synthesize large amounts of EPS. As the production of EPS is inversely proportional to the synthesis of polyhydroxybutyrate (PHB), research related to the production of PHB in different strains of rhizobia are underway in our laboratory, since this is a non-pathogenic bacteria, and was able to accumulate high concentrations of PHB when its cultivation was optimized (Proc. FAPESP 04/03344-3). Studies cited in the literature showed that with the advent of molecular biology techniques, and advances in genome sequencing have allowed a new approach for elucidating gene functions, by evaluating the phenotypes of mutations by obtaining from a specific gene. In this project we intend to build exoZ mutant gene involved in the synthesis of the repeating subunits of EPS and the genes phbA, phbB and phbC responsible for the synthesis of PHB in Rhizobium tropici SEMIA 4080. Thus, research related to genetic modification of this bacterium, both for understanding the biological role of these polymers, such as to analyze production and physicochemical characterizations are the initial steps for the biotechnological use of these biopolymers economically viable, since new techniques of gene manipulation tools are potentially useful in the production of EPS modified and adaptable to specific industrial uses. (AU)