Plant Growth-Promoting Halobacteria and Their Ability to Protect Crops from Abiotic Stress: An Eco-Friendly Alternative for Saline Soils

Abstract

Arid and semi-arid soils display low productivity due to abiotic stress associated with drought and salinity. Halobacteria can increase the yield of crops grown under these types of stress. These bacteria thrive across a wide salinity range (1–25% NaCl) and also in the absence of NaCl and have direct and indirect mechanisms that promote plant growth. This review summarizes studies conducted over the past five years that have assessed the effect of halobacteria on plants and soil fertility. The criteria used in the selection of halobacteria were also reviewed. Few studies have assessed the impact of halobacteria on soil fertility. The selection of halobacteria has been based on a qualitative criterion considering the morphology of colonies grown in media enriched with salts, mainly Na+. Not all bacteria growing in salt-enriched media are capable of capturing Na+ ions. Therefore, a quantitative criterion should be applied for the selection of halobacteria, which could be their ability to capture Na+ ions in vitro. This, together with the assessment of the effect of halobacteria on soil fertility, may largely contribute to the recovery of saline soils.