Characterization of plant growth-promoting diazotrops from salt-affected areas in the Philippines
2018
Ong, J.D.P. | Lantican, N.B. | Cruz, W.T. | Diaz, Ma.G.Q. | Paterno, E.S.
Soil salinity is an important factor limiting plant productivity worldwide. Studies have shown that plant growth-promoting bacteria can help plants tolerate salt stress. This study focused on the isolation and characterization of diazotrophs present in saline soils. Diazotrophs were isolated from the soil, plant rhizosphere and plant root samples obtained from Pampanga, Batangas, Iloilo, and Palawan in the Philippines. The 147 isolates were screened for 1-aminocyclopropane-1 carboxylic acid (ACC) deaminase activity, indole acetic acid (IAA) and siderophore production, and for phosphate solubilization. Ten isolates which tested positive for all of most of the plant growth-promoting traits were selected for further studies. BLAST analysis of the 16S rDNA showed that the microbial isolates were highly similar to members of Enterobacter sp., Serratia sp., Pseudomonas sp., Haererehalobacter sp., Salinicola sp., and Mangroveibacter sp. The nifH gene was detected in eight out of the 10 isolates. Under gnotobiotic condition, rhizosphere isolates AS10.2GPR and BPRP18.1 significantly increased the shoot dry weight of corn, cv IPB var 11 Magenta jars supplied with nutrient solution amended with 150 mM NaCl (15 dS/m), by 71.78% and 69.59%, respectively, relative to the uninoculated, nitrogen-free control. AS10.2GPR and BPRP 18.1 were highly similar to Serratia sp. NH10 (100%) and Enterobacter sacchari strain HX148S (99%), respectively.
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