Isolation and characterization of endophytic bacteria from rice (Oryza sativa L.)

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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was carried out to exploit diverse endophytic bacteria from 19 recommended rice and basmati rice varieties. Total 43 endophytic bacteria were isolated from root and leaf tissues of rice. On the basis of morphological and biochemical tests 81.5%, 81.4%, 67.5%, 16.3% and 7% isolates were positive for oxidase, nitrate reduction, methyl red, citrate utilization and Voges Proskauer’s, respectively. All endophytic bacterial isolates were positive for catalase test. Of 43 isolates 60.5%, 23.3% and 16.3% were tentatively assigned as Bacillus sp, Pseudomonas sp and Klebsiella sp, respectively. Further, all isolates were screened for multiple Plant Growth Promoting (PGP) traits viz. phosphate (P) and zinc (Zn) solubilization, production of indole acetic acid (IAA), 1-Aminocyclopropane-1-carboxylate (ACC) deaminase, siderophore, cell wall degrading enzymes, HCN, fluorescent pigment, urease and denitrification activity. Out of 43 endophytic bacterial isolates, 65.1%, 30.2%, 25.6% 18.6%, 18.6%, 16.3% and 4.6% produced fluorescent pigment, protease, denitrification, urease, siderophore, cellulase and zinc solubilization, respectively. Significantly high amount of IAA production was recorded with LRBLE1 (19.6 µgml-1) isolated from basmati rice variety Pusa 1592 followed by LRBLE4 (18.8 µgml-1) isolated from basmati rice variety PB 2. Significantly high P solubilization was observed in LRBLE1 (16.4 mg100ml-1) followed by LRBLE 4 (8.3 mg100ml-1). Highest ACC deaminase production was recorded with LRBLE1 (OD 0.555nm) followed by LRBLE 4 (OD 0.496nm). On the basis of above PGP traits 9 isolates (LRRE1, LRRE13, LRRE18, LRLE6, LRBRE4, LRBRE6, LRBLE1, LRBLE4 and LRBLE7) were subjected for colonization study using ampicillin (1 μgml-1) an antibiotic marker. Isolate LRRE1 (3.43) showed maximum log CFU/g root fresh weight. Further, on the basis of molecular characterization 3 endophytic bacterial isolates (LRBLE1, LRBLE4 and LRBLE7) were identified as diazotrophs due to presence of nifH gene. Six isolates (LRBLE4, LRBRE6, LRLE6, LRBRE4, LRBLE7 and LRRRE13) were detected as Pseudomonas sp with genus specific primer. On the basis of PGP traits and molecular characterization LRBLE1 and LRBLE4 were found promising diazotroph endophytic bacteria in rice.
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