A rhizosphere isolate from Oryza sativa, Enterobacter cloacae VITTPN2, as a potential plant growth promoting rhizobacteria; an in vitro study

Abstract

The increasing need for Plant Growth Promoting Rhizobacteria (PGPR) for biofertilizer development is warranted owing to the environmental hazards caused by chemical fertilizers. Our investigation was to isolate, screen and characterize PGPR from rhizospheric soil with potential PGPR properties. Oryza sativa and Saccharum officinarum rhizosphere were collected from the agricultural research station, Virinjipuram, Vellore (12.9202N, 79.1333E), Tamil Nadu, India for PGPR isolation. Eleven distinct isolates of bacteria were grown on Jensen’s (seven) and Pikovskaya’s media (four). Among these, four isolates (TPN1 to TPN4) showed phosphate solubilisation activity. And one isolate TPN2 particularly showed both nitrogen fixation and phosphate solubilization with other PGPR properties. Furthermore, the isolate TPN2 demonstrated promising results in Indole 3-Acetic Acid production (99.29±0.945µg ml-1). Since the isolate TPN2 displayed all PGPR characteristics under study, it was selected for pot culture studies. The seeds treated with TPN2 revealed an increase of 63.6% in shoot length and 14.63% in root length of the okra plant. There was a 74.6% increase in shoot length and a 16% increase in the root length of the tomato plant. Additionally, there was extensive development of lateral roots in okra plant. Henceforth TPN2 was identified as Enterobacter cloacae VITTPN2 (ku951582). This report produced remarkable results which promise the bacterial strain Enterobacter cloacae strain VITTPN2 can be further studied as a prospective biofertilizer.