ISSN: 2471-9315
Nguyen Thanh Trung, Ho Viet Hieu and Nguyen Huy Thuan
Aim: To isolate rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase and evaluate the ability of selected bacteria for improving the growth of cowpea seedlings under salt stress conditions.
Methods: This study isolates salt-tolerant rhizobacteria which have strong ability to produce ACC deaminase and the phytohormone indol-3-acetic acid (IAA). Inoculation experiments with selected bacteria strains were used to verify the plant growth promoting activity of bacteria under salt stress conditions.
Result: Two isolates belong to Enterobacter cloacae and one isolate belongs to Pseudomonas sp. have been identified. Those rhizobacteria were found to be highly salt-tolerant at salinity level up to 10% NaCl. The selected bacterial strains were also capable to produce and secrete large amounts of ACC deaminase and the phytohormone IAA into the growth medium. Cowpea plants inoculated with ST3 strain revealed a significant increase in shoot length and shoot fresh weight over uninoculated control at the salinity level of 1.5% NaCl.
Conclusion: Three rhizobacterial strains belonging to the genera Enterobacter and Pseudomonas have been isolated. All three bacterial strains were identified as moderate halophiles and they can produce high levels of ACC deaminase and IAA. The strain Pseudomonas sp. ST3 showed the possible ability to promote the growth of cowpea under salt stress conditions.