TASNIMUL BASHARAT, FERDAUSI ALI , TUHIN DAS, TAKIA BINTE BAKAR , NOWSHIN TARANNUM MISHI, JANNATUL FERDOUSE, MOHAMMAD SERAJ UDDIN AND TANIM JABID HOSSAIN*
Department of Biochemistry and Molecular Biology, University of Chittagong, Chattogram 4331, Bangladesh
*(e-email: tanim.bmb@gmail.com; Phone : 880 18120 92020 and seema@cu.ac.bd; Phone : 880 18120 92020)
(Received: November 8, 2022; Accepted: December 27, 2022)
ABSTRACT
Since phosphorus remains mostly in an un-utilizable form in soil, the phosphate solubilizing bacteria (PSB) can be employed to increase availability of soluble usable phosphorus in the rhizosphere. Three highly efficient phosphate solubilizing strains were screened out from the rhizospheric soil of BRRI-28 rice variety and characterized for plant growth promoting and abiotic stress tolerance properties. 16S rRNA gene sequence analysis identified the three isolates as Enterobacter and Klebsiella strains. They exhibited multiple plant growth promoting traits including auxin secretion, zinc solubilization, or ammonia production. The phosphate solubilizing and zinc solubilizing indices of the isolates were determined. Lipolytic activity was found to be the most common hydrolytic activity detected in all of the isolates. The PSB were further evaluated for their tolerance to different degrees of salinity (3 to 11% NaCl), drought (10 to 50% PEG-6000) and temperatures (20, 30 and 37°C). The isolates tolerated salinity stress up to 7% NaCl, drought stress up to 30% PEG-6000, and grew at all the tested temperatures with maximum growth detected at 30 or 37°C. Therefore, the phosphate solubilizing isolates can be considered candidates as microbial inoculants for plant growth enhancement and agricultural productivity under stress conditions.
Key words : Phosphate solubilizing bacteria, rice PGPR, abiotic stress tolerance, zinc solubilizing bacteria, auxin production, nitrogen-fixing bacteria