**5. Conclusions**

The results obtained here suggest that the three sweet potato genotypes studied showed a differentiated recruitment of members of the studied communities (phosphate mineralizers and nitrogen fixers). In addition, the IPB-137 genotype showed the highest number of copies of both genes studied with statistically significant differences compared to the other genotypes. Even though we know that the distribution of these communities may be directly related to the productivity of a given genotype, more studies are needed to trace this correlation in the field.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1424-2818/11/12/231/s1, Figure S1. DGGE fingerprints and UPGMA cluster analyses based on *alp* gene fragments (A) and *nifH* gene fragments (B) of phosphate mineralizing and nitrogen fixing bacterial communities, respectively, present in the rhizosphere of the tuberous roots (replicates 1–5 in parenthesis) from three different sweet potato genotypes (IPB-149, IPB-137 and IPB-052) sampled three (t1, \_3M - black squares) and six (t2, \_6M - grey squares) months after planting.

**Author Contributions:** Conceptualization, L.S. and J.M.M.; Data curation, A.F.B. and J.M.M.; Formal analysis, C.R.d.A.C., J.M.M., J.R.M., T.F.d.S. and L.S.; Funding acquisition, L.S.; Methodology, C.R.d.A.C., J.M.M., J.R.M. and T.F.d.S.; Project administration, L.S.; Resources, A.F.B.; Supervision, L.S.; Writing—original draft, J.M.M. and L.S.; Writing—review & editing, A.F.B., C.R.d.A.C., J.M.M., J.R.M., T.F.d.S. and L.S.

**Funding:** Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: 01; Conselho Nacional de Desenvolvimento Científico e Tecnológico; Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro.

**Acknowledgments:** The authors thank Simone Cotta for her help in qPCR experiments. This study was financially supported by the National Research Council of Brazil (CNPq), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

**Conflicts of Interest:** The authors declare that they have no conflict of interest.
