Measurement of ACC-Deaminase Production in Halophilic, Alkalophilic and Haloalkalophilic Bacterial Isolates in Soil

Strains with 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity can cause plant growth on stress condition. In the presence of bacteria with the ability of ACC deaminase production in the rhizosphere, it is possible to convert the ethylene precursor (ACC) to α-ketobutyrate  and ammonium, reducing the ethylene levels in host plants. In order to measure the power and level of ACC deaminase production in halophilic, alkalophilic and haloalkalophilic microbial isolates, soil samples were collected from six different areas of Khorasan Razavi Province and bacterial isolates were separated and purified. The haloalkalophiles isolates showed the maximum ACC deaminase production (0.4374 mM) among the three groups of isolates, followed by alkalophiles isolates (0.241 mM) and halophiles (0.0848 mM). Equations to predict the concentration of ACC deaminase production were only significant in the halophilic isolates (probability level= 1.0) under the effect of electrical conductivity and pH at 0.01 probability level. Also, the multiple regression analysis for predicting ACC deaminase production by isolates had significant performance in low concentrations, while at higher concentrations of the enzyme other factors were effective in ACC deaminase production. The higher ACC deaminase productivity power of haloalkalophilic isolates makes them interesting for basic biotechnology studies.