en Other Other Original Article Original Article <div style="text-align: justify;">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 <a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjvkvbnmKrMAhXMiCwKHTzODOsQFggoMAE&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F4062289&usg=AFQjCNHibfKv3t6QsSmkc9wLwroPVOy8CQ&sig2=t4X7WIacKjM4GiMvjXO-cw">&alpha;-ketobutyrate</a>&nbsp; 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.</div> Stressed ethylene, salinity stress, ACC deaminase, haloalkalophilic bacteria 194 202 http://ibbj.org/browse.php?a_code=A-10-219-1&slc_lang=en&sid=1 Mehrnoush Eskandari Torbaghan mehrnoosh.eskandary@gmail.com 10031947532846002841 10031947532846002841 Yes Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Amir Lakziyan lakzian@ferdowsi.um.ac.ir 10031947532846002842 10031947532846002842 No Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Ali Reza Astaraei astaraei@.um.ac.ir 10031947532846002843 10031947532846002843 No Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Amir Fotovat afotovat@.um.ac.ir 10031947532846002844 10031947532846002844 No Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Hossein Besharati besharati1350@yahoo.com 10031947532846002845 10031947532846002845 No Soil and Water Institute, Agricultural Research, Education and Extension Organization, Karaj, Iran.