Isolation of halo-tolerant bacteria with plant growth-promoting traits

Over the last decades, world agriculture has suffered from soil salinity problems such as nutrient deficiency and salt toxicity. The use of plant growth-promoting bacteria (PGPR) has been widely reported to alleviate salt stress and promote plant growth via various mechanisms including the decrease in ethylene levels and the increase of bioavailability of nutrients. We have tested 39 bacteria stains for their plant growth-promoting traits such as 1-aminocylopropane-1-carboxylate (ACC) deaminase, indole acetic acid (IAA) production as well as phosphate solubilization. The results showed that 33 isolates produced ACC deaminase, ranging from 0.3 to 35.0 µmol -KA/mg/h and 27 isolates produced IAA from 1.4-59.9 µg/mL. Sixteen isolates showed the ability to solubilize bio-unavailable phosphate, resulting in halo-zones in the size of 1.5 to 13.3 mm, with 7 isolates of phosphate solubilization index above 2.0. To conclude, isolates with great potential for plant growth promotion have been isolated. The application of these isolates can be an option to replace chemicals used in current agriculture practices and help the development of sustainable agriculture.