Endophytic bacteria isolated from ip mirim (Tecoma stans Bignoniaceae) and its application for plant growth promotion

Abstract

Endophytes are usually protected from soil environment competitiveness and stress. However, the presence of heavy metals can negatively affect the structure and diversity of endophyte communities. The aim of the present study was evaluate the diversity of endophytic bacteria from ipê mirim (Tecoma stans Bignoniaceae) grown in an area of Atlantic rainforest contaminated with metals and evaluate the ability of these bacteria to promote plant growth and seed germination. Results show that endophytic bacterial density in plants was stable among sites with different level of metals; however, bacterial richness was lower in plants from sites with low level of metals. At least 28 genera were isolated, where Methylobacterium (21.32%), Bacillus (19.12%), Pseudomonas (11.03%) and Curtobacterium (7.35%) the dominant groups. Isolates were selected from Rhizobiales order and the capability of this dominant group in plant growth promotion was evaluated. Results showed that Methylobacterium spp. and Rhizobium sp. increased germination and improved seedling growth of tomato Santa Cruz Kada Gigante. Therefore, results show that the endophyte cultivable community is not influenced by the presence of low metal concentration, and plant growth promoter bacteria that can be used on tomato seedlings production were successfully selected and on future phytoremediation studies.