Insights into the plant growth promotion properties of bacterial endophytes isolated from Alternanthera philoxeroides and Eichhornia crassipes from Bellandur lake, India

Abstract

The presence of macrophytes such as Alternanthera philoxeroides and Eichhornia crassipes in Bellandur Lake, India, has been observed despite the high pollution levels. Our research aims to explore the potential role of endophytes in promoting the growth of these macrophytes in such heavily contaminated environments. In current study, we isolated 20 endophytic bacteria from various parts of A. philoxeroides (12) and E. crassipes (8) plants, including shoots, roots, leaves, and flowers. We found that a significant proportion of endophytes from A. philoxeroides (42 %) and E. crassipes (25 %) produced more than 100 µg/mL of indole acetic acid (IAA). Similarly, the majority of the isolates possessed other plant growth promoting traits like ammonia production, nitrogen fixation, phosphate and potassium solubilization, siderophore production, and ACC deaminase production. Many of these isolates demonstrated extracellular enzyme production and halotolerance properties. We identified Acinetobacter soli ON529869 and Bacillus licheniformis ON506048 as the most effective plant growth promoters among the isolates, which also displayed antifungal properties against Fusarium solani and Cladosporium tenuissimum in vitro. Furthermore, greenhouse trials using these two endophytes revealed their significant plant growth promotion abilities in Amaranthus viridis. The pigment indices were evaluated using CI-710 Leaf Spectrometer. In conclusion, our findings provide compelling evidence for exploring the endophytic microbiomes of macrophytes in polluted areas for sustainable agriculture and bioprospecting of unique traits. This research could lead to the discovery of new and valuable resources for agricultural practices and other applications.