Detection and Enumeration of Bradyrhizobia Cells by Real-Time PCR Quantification
Karla Cristina Stropa Goulart, Eliana Gertrudes de Macedo Lemos, Jackson Antônio Marcondes de Souza

Bradyrhizobiumelkanii and Bradyrhizobiumjaponicum are nitrogen-fixing bacteria that establish symbiosis with soybean plants. The optimization of this symbiosis and the success of biological nitrogen fixation are reached by inoculating the seeds with strains of bradyrhizobia. The aim of this work consisted in the enumeration of bacterial cells of inoculants from different ages by real-time PCR quantification (qPCR) based on 16S rDNA and the evaluation of surviving cells rates under desiccation experiments. The results of counting by colony forming units (CFU) were correlated with those obtained by qPCR. All qPCR values were higher than those for CFU values in cell enumeration for all samples and conditions observed. Cell resistance to desiccation was shown until 24 hours onto soybean seeds, with considerable fall in all the inoculants after 48 hours under desiccation. This was probably due to biochemical and physiological changes in its metabolism, making use of defensive mechanism to the adverse conditions for its survival.

Full Text: PDF     DOI: 10.15640/jaes.v4n1a19