Isolation and Identification of ACC Deaminase Producing Bacteria from Rhizosfer and Plant Roots of Maize, Cowpea, and Groundnut Growing under Saline Stress

Abstract

ACC deaminase producing bacteria reduces the excess ethylene produced by stressed plant because ACC deaminase catalyzes the cleavage of ACC into ammonium and α-ketobutyrate. ACC deaminase is produced by several rhizospheric and endophytic bacteria. This study was aimed to obtain ACC deaminase producing bacteria isolated from rhizosfer and plant roots of maize, cowpea, and groundnut growing under saline stress. Isolation was conducted by surface plating on NA medium. Qualitative selection was based on the growth of isolate on DF salts medium supplemented with AIB. Quantitative selection based on ACC deaminase activity assay. Identification of the isolates was carried out by morphologycally and sequencing of 16S rRNA gene. Isolation and selection resulted four bacterial isolates (AJG3, RJG6, ATL5, and RTN10). Those bacterial isolates have the ACC deaminase activity between 184.65 to 692.54 nmol α-ketobutyrate. mg−1. h−1. Isolate of AJG3, RJG6, and ATL5 were gram negative bacteria, only one isolate was gram positive bacteria (RTN10). Based on 16S rRNA gene sequence, AJG3, RJG6, ATL5, and RTN10 isolates have a high similarity with Klebsiella variicola, Rhizobium pusense, Agrobacterium tumefaciens, and Bacillus stratosphericus respectively.