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Indole‐3‐acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in P antoea dispersa strain GPK
Author(s) -
Kulkarni G.B.,
Nayak A.S.,
Sajjan S.S.,
Oblesha A.,
Karegoudar T.B.
Publication year - 2013
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12053
Subject(s) - tryptophan , pantoea , indole 3 acetic acid , amino acid , bacteria , biochemistry , rhizosphere , shoot , biology , aromatic amino acids , strain (injury) , phenylalanine , biosynthesis , methionine , dioxygenase , food science , pseudomonas , enzyme , auxin , botany , gene , genetics , anatomy
This investigation deals with the production of IAA by a bacterial isolate P antoea dispersa strain GPK ( PDG ) identified by 16 S rRNA gene sequence analysis. HPLC and M ass spectral analysis of metabolites from bacterial spent medium revealed that, IAA production by PDG is T rp‐dependent and follows indole‐3‐pyruvic acid ( IP y A ) pathway. Substrate specificity study of aromatic amino acid aminotransferase ( AAT ) showed high activities, only when tryptophan ( T rp) and α‐ketoglutarate (α‐kg) were used as substrates. AAT is highly specific for T rp and α‐kg as amino group donor and acceptor, respectively. The effect of exogenous IAA on bacterial growth was established. Low concentration of exogenous IAA induced the growth, whereas high concentration decreased the growth of bacterium. PDG treatment significantly increased the root length, shoot length and dry mass of the chickpea and pigeon pea plants. Significance and Impact of the Study This study demonstrates the Indole‐3‐acetic acid ( IAA ) producing and plant growth‐promoting abilities of P antoea dispersa . This study confirms the IAA biosynthetic pathway used by this bacterium. The work also signifies the role of exogenous IAA on bacterial growth, which may act as signalling molecule in rhizosphere.