Screening of Brazilian cacti rhizobacteria for plant growth promotion under drought

Abstract

Drought is one of the major problems worldwide. The search for new and efficient microorganisms, from unexplored environments, to be used in association with plants to alleviate the negative effects imposed by water stress, is an interesting alternative. Thus, cacti-associated bacteria from the Brazilian semi-arid region were isolated based on their ability to grow in medium with reduced water availability. Strains were tested for the production of exopolysaccharides (EPS), as well as in vitro plant growth promotion traits. A great proportion of the isolates belong to the genus Bacillus. From a total of forty-eight bacteria, 65% were able to grow in medium with reduced water availability (0.919Aw), exopolysaccharide production was observed for 65% of the strains. The production of indole acetic acid (IAA) exceeding 51μgmL(-1) was observed for 4% and the high solubilization of Ca-P was verified for 6% of the isolates. No strain was able to produce hydrogen cyanide (HCN), 71% produced ammonia and 79% showed a halo of carboxymethyl cellulose (CMC) degradation. Zea mays L. growth promotion under water stress (30% of field capacity) was achieved by two strains of Bacillus spp. This is the first report to describe cacti-associated bacteria from Brazilian semi-arid with plant growth-promoting abilities.

Isolation and selection of plant growth-promoting bacteria associated with sugarcane

“…Babalola & Odhiambo (2008) also found that this genus promoted growth in maize. Enterobacter and Pantoea have also been described as promoting growth in this crop (Morales-García et al 2011, Kavamura et al 2013 Photo: Ariana Alves Rodrigues…”

“…Seeds from a landrace variety (purple maize or Palha Roxa, in Portuguese) of Zea mays L. not treated with fungicide or insecticide were initially sterilized (Kavamura et al 2013). The seven previously selected microorganisms were cultured in 10 % TSB for 24 h and their concentration was adjusted in a spectrophotometer for 10 8 cells mL -1 (OD550nm = 0.1).…”

The Resurrection Plant Tripogon Spicatus (Poaceae) Harbors a Diversity of Plant Growth Promoting Bacteria in Northeastern Brazilian Caatinga

“…Other species native to the Caatinga, for example cactus species, also harbor plant growth promoting bacteria related to those taxa, belonging to the Pantoea and bacillus genera (Kavamura et al, 2013). Furthermore, related bacteria were also isolated from Cactaceae and Poaceae at different sites around the world, including dry land environments (Peng et al, 2009;Puente et al, 2009;Lopez et al, 2011).…”

“…In Brazil, few plant groups have been studied only in the last few years (Costa and Melo, 2012;Fernandes Júnior et al, 2013;Kavamura et al, 2013). Recently, bacteria from native cactus species growing in the Caatinga were isolated, and evaluation of their physiological features and ability to promote plant growth indicated the presence of bacteria with biotechnological applications that promote the growth of cowpea (Costa and Melo, 2012) and maize (Kavamura et al, 2013). In spite of those physiologically peculiar characteristics, the resurrection plants inhabiting the Caatinga biome have not yet been evaluated in regard to the presence of PGPB.…”

Rizobactérias nativas da Caatinga com potencial para redução dos efeitos da seca em soja (<i>Glycine max </i>L.)

“…entre os isolados, moderada, alta e elevada produção desta auxina. De acordo com a concentração de AIA detectada, temos: < 1ug.mL -1 (baixa produção); 1-10 µg.mL -1 (média produção); 11-50 µg.mL -1 (alta produção) e > 51 µg.mL -1 (elevada produção) (KAVAMURA et al, 2013 Tabela 6 -Caracterização dos isolados como: positivo ou negativo para a produção de EPS de acordo com o tamanho do halo com aspecto mucoide, sendo + (pouca produção -halo de EPS ≤ 10 mmØ), ++ (média produção -halo de EPS de 10-14 mmØ) e +++ (ótima produção -halo de EPS ≥ 14 mm) (CHOWDHURY et al, 2011;KUMAR et al, 2004;ZHAO;WU, 2010). Paenibacillus jamilae também é uma espécie conhecida por produzir EPS (AGUILERA et al, 2001).…”