The medium mixture of M79:LB at a proportion of 8:2 was the most CYT387 suitable for culturing both bacteria and it was designated as MLB medium. Another requisite for the conjugation procedure is to select vectors that contain proper selection markers that are mobilizable and able to replicate inside the receptor cell [19, 20]. Therefore, the pHRGFPGUS (pBBR1 replication Saracatinib origin) and the pPZPLACEYFP (pVS1 replication origin) plasmids were tested by tri-parental conjugation. These plasmids are mobilizable broad-host vectors harboring kanamycin resistance markers and fluorescent protein
coding genes, which could promptly report achievement of the DNA transfer. The transconjugants exhibited kanamycin resistance and fluorescence. The conjugation frequencies were 3.8 × 10-8 per recipient cell for the pHRGFPGUS vector
and 3.8 × 10-7 for the pPZPLACEYFP vector. Different ratios of recipient to donor and helper strains (1:1:1, 5:1:1, 10:1:1 and 20:1:1) were also tested. The best efficiencies were obtained with the ratios 10:1:1 and 5:1:1; however, no obvious differences between these latter ratios were observed (data not shown). In conclusion, conjugation is an appropriate method for DNA transfer to A. amazonense. Although only tri-parental mating was tested in this work, it is important to mention that bi-parental conjugation could be an alternative test, due to the possibility of increasing the conjugation efficiencies. Electrotransformation PRN1371 Since suitable vectors for A. amazonense were defined and since conjugation is a time-consuming procedure, the transformation of A. amazonense via electroporation was tested. The eletrocompetence of the cells is greatly influenced by the growth phase .
Therefore, A. amazonense cells were harvested at different growth phases to evaluate their effect on electroporation efficiency. Cells from the late-log phase (OD600 1) and the stationary phase (OD600 2) were not electrocompetent. Electroporation utilizing cells from the early-log growth phase (OD600 0.12) generated a significant number of transformants. Therefore, all subsequent tests were performed utilizing cells cultivated at this growth phase. In the electrocompetent Etofibrate cell preparation, the cells were harvested and washed continuously until the solution had a low-ionic strength. The MgCl2 HEPES-sucrose buffer was found to be the most suitable solution for the preparation of A. amazonense electrocompetent cells. Although 10% glycerol solution is commonly used for electrocompetent cell preparation in a diverse number of species (including A. brasilense), it was not appropriate for A. amazonense, as no transformants were obtained when this solution was used. Different electroporation parameters were tested. The increase in electrical field strength had a positive effect on electroporation efficiency (Figure 2A). The highest electrical field strength tested was 12.