Abstract
The family Acetobacteriaceae currently includes three known nitrogen-fixing species,
Gluconacetobacter diazotrophicus, G. johannae and G. azotocaptans. In the present study, nitrogen fixing
bacteria were isolated from sugarcane and rice roots cultivated in Aswan and Qalubia Governorates,
respectively. Seven isolates from sugarcane roots and three isolates from rice roots gave the basis phenotypic
characteristics of Gluconacetobacter sp. These isolates were examined for plant growth promotion activities
such as indole acetic acid (IAA) and gibberellins (GA3) production in addition to their putative endophytic
features such as cellulase and pectinase production. Rice seeds (Oryza officinalis) colonizing ability with the ten
Gluconacetobacter isolates in vitro was examined. The ten Gluconacetobacter isolates were examined for their
antagonistic activity against pathogenic fungi and bacteria in addition to their ability to produce hydrogen
cyanide (HCN) and siderophores.Sodium dodecyle sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is a
technique used for the characterization and analysis of proteins for identification of bacterial isolates and
yielding valuable information on the similarity and dissimilarity amongst bacterial cultures.