Isolation of ACC-deaminase producing plant growth promoting rhizobacteria from Oryza sativa

The overwhelming challenges of climate change and increased population trigger the roar of food productivity. Untamed environmental stress conditions have become a harsh reality in the sustainable development of agriculture. This scenario has led to the regularization of fertilizers in agriculture, which has further raised concerns. Given this, the present study reports the isolation of ACC deaminase-producing rhizobacteria from the stress-prone crop Oryza sativa from Punjab, India, targeting a sustainable solution for agriculture. A total of 50 isolates were identified from 9 districts of Punjab by primary screening on ACC-supplemented DF media. Further, all the isolates were quantified for ACC deaminase production, and the highest production was observed for CJSKII3, i.e., 0.89±0.02 µM/mg protein/h, and the minimum production was noted for NGNI, i.e., 0.52±0.0 µM/mg protein/h. Out of 50 isolates, 6% of rhizobacteria were able to produce IAA, 74% for biofilm production, 38% for nitrogen fixation, 40% for siderophore production, 12% for HCN production, and 54% for phosphate solubilization. They were also identified for 16% protease production, 22% amylase production, and 52% rhizobacteria showed antifungal activity against the fungus Fusarium oxysporum. Three rhizobacteria, i.e., CJSKII3, NARI2, and NARI4, showed prominent results with maximum PGPR activities. All three were identified by 16S rRNA molecular sequencing as Bacillus tropicus, Alcaligenes aquatilis, and Alcaligenes faecalis. As a promising stress-diminishing trait, these ACC deaminase-producing PGPRs can further be assessed in agriculture as an effective biofertilizer.