Isolation, Characterization, and Investigation on Potential Multi-trait Plant Growth Promoting Rhizobacteria from Wild Banana (Musa itinerans) Rhizospheric Soil

Abstract

The undertaken study was conducted to isolate and characterize the plant growth promoting rhizobacteria from the rhizospheric soil of Musa itinerans collected from Zaphumi village, Nagaland, Northeast India. The purified bacterial isolates were screened for plant growth-promoting traits namely phosphate solubilization, IAA production, siderophore production, and ammonia production. Out of the 25 isolates, the three best isolates with maximum growth promoting traits were selected and considered for further study for heavy metal and salinity tolerance. All three isolates were able to produce siderophore, whereas, only isolate EZ30 was able to produce IAA. Phosphate solubilization ability was the highest in EZ27 (272.89±2.46), followed by EZ30 (109.70±5.47) and EZ11(89.12±1.87). The isolates also exhibited variable levels of cadmium (30- 280µg/ml) and salinity resistance (2-14%). Based on 16S-rRNA gene sequence analysis, these bacterial isolates were identified as Kosakonia arachidis, Pseudomonas putida and Pseudomonas monteilii. The highest salinity tolerance was shown by P. putida (14%), whereas K. arachidis (4%) and P. monteilii (4%) exhibited similar level of tolerance. The cadmium tolerance was the highest for P. monteilii (280 µg/ml), followed by K. arachidis (80 µg/ml) and P. putida (30 µg/ml). Inoculation of Cicer arietinum L. with these three isolates significantly enhanced the growth parameter such as shoot and root length (p≤ 0.05), root and shoot fresh weight and dry weight (p≤ 0.05), except for EZ27 and EZ11 where there was no significant difference in shoot dry weight (p≥ 0.05). Overall, the three selected PGPR strains showed potential biofertilizer traits (phosphate solubilizing, IAA producing, siderophore production, salinity, and cadmium tolerant) to be used in the agricultural fields promoting sustainable practices.