The quantitation of Bradyrhizobium japonicum communities and the isolation of bacteriocin-producing Bradyrhizobium strains from Manitoban soil
Loading...
Date
2016
Authors
Yudistira, Harry
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Bradyrhizobium japonicum is a Gram negative α-proteobacteria capable of reducing atmospheric nitrogen to ammonia while in a symbiotic relationship with soybean. This symbiosis manifests itself as nodules formed on the roots of soybean plants. A well-nodulated plant can derive all the nitrogen necessary for growth from this association. One problem that is often encountered is not having sufficient numbers of the correct strains of rhizobia present as the seed is germinating which prevent effective nodules to develop in a timely manner. Currently, the quantification of Bradyrhizobium in soil relies heavily on culture-based assays which are time-consuming, labour-intensive, and lacks the ability to differentiate between strains of B. japonicum. In this study, we developed a rapid and sensitive real-time qPCR based assay for the quantification of B. japonicum. This assay is able to differentiate between strains of B. japonicum. Using this assay, we showed the differences in the composition of B. japonicum community in fields utilizing narrow (15 inches) and wide (30 inches) row spacing. We showed that the composition of B. japonicum community in soil is affected by the population density of host plants. We also isolated B. japonicum strain FN1 in Manitoba. FN1 produces substances with bacteriocin-like characteristics that inhibit the growth of multiple other strains of Bradyrhizobium. In this study, we were able to identify a gene that is responsible for the production of the bacteriocin-like substance that inhibits the growth of the strain SR-16. Furthermore, we showed that the ability of FN1 to produce bacteriocin-like substance provide a competitive advantage for nodule occupancy over SR-16. This is the first study in B. japonicum that shows that the ability to produce bacteriocin-like substance is related to the competitiveness for nodule occupancy.
Description
Keywords
Bradyrhizobium japonicum, Soybean, Bradyrhizobium, Quantitative real-time PCR, Bacteriocin, Nodule occupancy