The endophytic bacteria found inside the stems would be better protected against the antimicrobial effect of the essential oil. To support this argument, the susceptibility of the bacterial isolates to the essential oil obtained from L. sidoides genotypes LSID006 and LSID104 was determined. The essential oil from the genotype LSID006 was chosen to represent the ones from LSID003 and LSID105 which are Bromosporine datasheet Similar in their
thymol and carvacrol contents. MIC determination showed that 85.7% and 74.6% of the strains tested presented a MIC ≥ 0.25 mg ml-1 of essential oil from genotypes LSID006 and LSID104, respectively, CB-839 manufacturer suggesting an intermediate sensitivity of the isolates to the presence of both essential oils. However, no difference in the susceptibility range could be observed between the stem-derived and leaf-derived strains. It is important to state that the number of leaf-derived strains tested was much lower than the number of stem-derived strains, thus compromising the interpretation of the results obtained. In total,
145 endophytic Metabolism inhibitor bacterial isolates were obtained mostly from the stems. Our results suggest that the most dominant group associated with the L. sidoides genotypes was the Gammaproteobacteria, which is consistent with other studies [33, 37, 38]. Isolates from the genera Bacillus and Paenibacillus (belonging to the Firmicutes) were mainly obtained from LSID105 leaves (Figure 4). Because
members of these genera are spore formers, they may have resisted exposure to the essential oil after maceration of the leaves. Although we do not know whether Selleck Ibrutinib the isolated strains have any plant growth promoting potential, other studies have already demonstrated the importance of the different genera found here as nitrogen fixers, phosphate solubilizers and/or auxin producers in other plants [39, 40]. As the cultivation-dependent methodology used was affected by cell death in the leaves, the PCR-DGGE approach chosen to determine the structure of the microbial communities found in the leaves and stems of L. sidoides became crucial to this study. Moreover, it allowed access to the communities (such as the Alphaproteobacteria, Betaproteobacteria and Actinobacteria) possibly present in lower numbers or that failed to grow under the conditions used for isolation. Similar results were obtained when the total bacteria (accessed by two different sets of primers for PCR amplification), Alphaproteobacteria and Betaproteobacteria communities were considered. Slight differences in DGGE profiles were observed among the genotypes; nevertheless, these differences did not contribute to the grouping of the different communities as much as the location in the plant (stem or leaf) where these communities were found.