Preliminary Screening for ACC-deaminase Production by Plant Growth Promoting Rhizobacteria

Ethylene is well thought-out stress hormone because its synthesis is induced by a variety of stresses. Nodulation and subsequent nitrogen fixation by lentil plants are inhibited by accelerated ethylene concentration in the root zone. Some plant-growth-promoting rhizobacteria (PGPR) promote plant growth by lowering the endogenous ethylene synthesis in the roots through their 1-aminocylopropane-1-carboxylate (ACC)-deaminase activity. A total of 9 rhizobacterial isolates obtained from lentil rhizospheric soils were characterized and found belonging to genera Bacillus (6), Pseudomonas (3), which were able to utilize ACC as the sole N-source, their ACC-metabolizing rate measured as optical density (OD496) and (OD600) ranged from 0.54-1.39 and 0.165-1.120 respectively. The isolates also showed compatibility with Rhizobium leguminosarum under axenic conditions and also promoted root/shoot growth in lentil seedlings. Our results reveal that inoculation with PGPR containing ACC-deaminase and Rhizobium could be utilized as expeditious biofertilizers to increase the growth as well as nodulation in legume plants.