Endophytic microbiota of floating aquatic plants: recent developments and environmental prospects

Plant-associated microorganisms play a critical role in plant survival and functional attributes. There are many studies on the taxonomical and functional aspects of microorganisms associated with terrestrial plants. However, the microbiome of aquatic plants is not much explored. This work details the studies on microbiomes and diversity in microbial communities inhabiting the three common free-floating aquatic plants of tropical regions viz. duckweed, water hyacinth and water lettuce, widely implicated for their bioremediation potential. Studies conducted till date reveal the prevalence and dominance of different Bacillus sp. Other genera, including Rhodanobacter, Pseudomonas, Rhizobium, Achromobacter, Serratia, Actinobacteria, Proteobacter, Klebsiella and Acidobacteria, have also been prominently reported. This lesser explored niche offers great bioprospecting opportunities to obtain taxonomically diverse and functionally distinct microorganisms. Bacterial endophytes from these aquatic plants have been primarily studied for their ability to produce indole acetic acid and degrade phenol. Limited studies reveal some fungal endophytes to have promising herbicidal effect. Not much is known on other functional attributes and hence microbial studies on these plants holds much promise for obtaining novel isolates or isolates with novel functions that would impact both aquatic and terrestrial ecosystems. This study proposes the need for exploring the role of endophytes as biocontrol agents and their potential to provide a pragmatic and robust solution to the aquatic weed menace in freshwater bodies. Bioprospecting of this lesser studied ecological niche hence is a promising field of research that has both environmental and economic potential.