Isolation, bioprospecting and diversity of salt-tolerant bacteria associated with sugarcane in soils of Pernambuco, Brazil

Maria C B S Leite,Fernando J Freire,Fernando D Andreote,Júlia Kuklinsky-Sobral,Maria B G S Freire,Andreza R B De Farias

doi:10.1590/1807-1929/agriambi.v18nsupps73-s79

Maria C B S Leite, Fernando J Freire + Show 4 more

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https://doi.org/10.1590/1807-1929/agriambi.v18nsupps73-s79

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Abstract

ABSTRACT The selection of salinity tolerant bacteria may provide greater promotion of plant growth in soils with salt stress. This study aimed to isolate and select bacterial isolates of sugarcane, tolerant to salinity and plant growth promoters, and assess genetic diversity. To do so, endophytic root and rhizosphere of sugarcane, were isolated in culture medium with and without NaCl. The bacterial population density, the potential for biological nitrogen fixation (BNF), production of indole acetic acid (IAA), inorganic phosphate solubilization and quorum sensing molecule production were evaluated. Furthermore, the genetic diversity was assessed by Denaturing Gradient Gel Electrophoresis (DGGE) of nifH. Salinity tolerance tests were also conducted. There was no statistical difference in population density. As for the potential for BNF, IAA production, phosphate solubilization and quorum sensing molecule production, there was a high percentage of positive isolates. In the technique of DGGE nifH, the dendrogram showed high genetic variability. So there was the selection of bacteria that can contribute to the better development of sugarcane in saline soils.

Highlights

The sugarcane (Saccharum spp.) is an important crop in Brazil and besides the corn in the United States, is responsible for most of the ethanol produced in the world (Waclawovsky et al, 2010)
Soil samples were analysed for chemical characterization, soil pH and electrical conductivity of the saturation extract (EC), levels of available P, K+, Na+, Ca2+, Mg2+, Al3+, H+Al, the sum of bases (SB), the cation exchange capacity (CEC) and base saturation (V) were determined by the methods described in EMBRAPA (1997) (Table 1)
As the bacterial population density, it was observed that there was no statistical difference between the niches, rhizosphere and root endophytic; between treatments with and without application of vinasse, and with the presence or absence of salt

Summary

Introduction

The sugarcane (Saccharum spp.) is an important crop in Brazil and besides the corn in the United States, is responsible for most of the ethanol produced in the world (Waclawovsky et al, 2010). When applied to the soil, vinasse causes a series of changes in its chemical and physical characteristics, especially in pH, cation exchange capacity (CEC), organic carbon, water retention, electrical conductivity, porosity, and affecting population and. Bacteria that are in association with sugarcane, exhibit variation in salinity tolerance and its characteristics which promote plant growth, such as nitrogen fixation, production of phytohormones, solubilization inorganic phosphate, among others (Nobrega et al, 2004) may be affected. This situation can be mitigated by using bacterial strains tolerant to salt stress. These bacteria are known as halotolerant, not require salt for metabolism but tolerate salts at different concentrations (Mishra et al, 2011)

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