Plant cell-wall degrading hydrolytic enzymes of Gluconacetobacter diazotrophicus

The strains PA15 and UAP5541 of Gluconacetobacter diazotrophicus were able to produce endoglucanase (EG), endopolymethylgalacturonase (EPMG) and endoxyloglucanase (EXG) enzymes using sucrose or the corresponding substrate as the sole source of carbon. The results indicate that the hydrolytic activity of the PA15 strain was inducible, whereas that of the UAP5541 strain seems to be constitutive (regardless of the concentration of sucrose used). When the concentration of the enzymatic substrates was increased in the culture medium, the production of hydrolytic enzymes decreased. The different behaviour of the strains PA15 and UAP5541 grown in the culture medium with different concentrations of sucrose and the enzymatic substrates demonstrates, that the microbial response and the control of the enzymatic expression of G. diazotrophicus strains were different and complex and may be important in their capacity to penetrate plant root as well as in their competitive capacity against other microorganisms.