The ability of ACC deaminase production in isolated bacteria from drought, saline and saline-sodic soils and selection of the most efficient bacteria

Drought, salinity and salinity-sodicity conditions reduce plant growth, due to stress ethylene biosynthesis. Because of capability of some soil bacteria for stress alleviation, and ACC consumption, this investigation was carried out to select the best ACC deaminase producer bacteria in conditions of drought, salinity and salinity-sodicity affected soils.
In this investigation, 400 bacteria were isolated from soils with different levels of electrical conductivity (EC) and sodium adsorption ratio (SAR) and analyzed the variability of their ability in ACC consumption and α- ketobutyrate as indices of ACC deaminase production. Also, the effects of different drought and salinity stress on bacteria growth trend and ACC consumption ability were analyzed.
Data analysis indicated that, not only the ability of ACC production was different among isolates, but also amounts of ACC consumption were affected by drought and salinity tensions. In the most isolates, there was a significant decrease in trend of ACC deaminase production as affected by tensions. But, one of bacterial species as Bacillus simplex that was isolated from saline-sodic soils, in addition to ability of production of 901 nmole α- ketobutyrate per milligram protein per hours in normal conditions, has the highest production stability in drought and salinity tensions. Also, this bacterium was continued to ACC deaminase production up to EC of 40 dS.m-1 and OP (Osmosis pressure) of -25 bar.
Discussion and According to comparison among isolates, B. simplex has the highest efficiency of ACC deaminase production, in drought and salinity conditions, and was tolerant to these tensions. Therefore, B. simplex was proposed for field experiments in drought, salinity and salinity-sodicity affected soils.