Bradyrhizobium
Like other rhizobia, many members of this genus have the ability to fix atmospheric nitrogen into forms readily available for other organisms to use.In a liquid medium, Bradyrhizobium species take 3–5 days to create a moderate turbidity and 6–8 hours to double in population size.The expression of these genes results in the production of enzymes called Nod factors that initiate root hair curling.Ribosomal RNA is highly conserved in this group of microbes, making Bradyrhizobium extremely difficult to use as an indicator of species diversity.Some strains are photosynthetic, these Bradyrhizobium often form nodules in the stems of semi-aquatic Aeschynomene legumes, and have also been found in the nodal roots of African wild rice Oryza breviligulata.Bradyrhizobium has also been identified as a contaminant of DNA extraction kit reagents and ultrapure water systems, which may lead to its erroneous appearance in microbiota or metagenomic datasets.[17] The presence of nitrogen-fixing bacteria as contaminants may be due to the use of nitrogen gas in ultrapure water production to inhibit microbial growth in storage tanks.