Occurrence, Characteristics, and Genetic Diversity of Azotobacter chroococcum in Various Soils of Southern Poland

The presence of Azotobacter sp. in soils has beneficial effects on plants, but the abundance of these bacteria is related to many factors, especially soil pH and fertility. The presented study evaluated the abundance of Azotobacter sp. in various soils of southern Poland and confirmed the relationship between soil properties and the presence of these bacteria. Diagnostic tests indicate that all isolates belonged to A. chroococcum species. The studied bacteria were present in 43% of soil samples. Restriction analysis of the bacterial Internal Transcribed Spacer region indicate that the selected isolates were identical. Two fingerprinting methods, PCR Melting Profile and Random Analysis of Polymorphic DNA, revealed high population diversity. Four (PCR MP) and five (RAPD) congruent clusters were defined. No correlation was found between the sources of strain isolation and their positions in clusters. PCR MP and RAPD techniques appeared to be useful in intraspecies differentiation of A. chroococcum.