Effects of Ectophytic Bacteria in Phytoremediation

Abstract

Treating wastewater has become one of the challenges faced by people living in an urban area. Due to anthropogenic activities, the water quality has been decreasing drastically, and we felt the need to address the issue at the earliest. Therefore, this study was conducted to analyze the effectiveness of symbiotic bacteria in phytoremediation using two aquatic plants, Echinodorus cordifolius (L.) Griseb. and Lepironia articulata (Retz.) Domin. Aquatic plants were treated with sodium hypochlorite to sterilize plant roots, and cultured in domestic wastewater for five days. The water samples were analyzed for the levels of phosphate (PO43), ammonium (NH4), nitrate (NO3) and nitrite (NO2). In addition, roots were collected for 16S rRNA gene-based metagenomics analysis of bacterial composition. The results showed that the removal percentage of PO43, NH4+, NO3, and NO2 of unsterilized plants were higher than sterilized plants. Moreover, the 16S rRNA gene-based metagenomics analysis revealed that the dominant bacterium in control E. cordifolius was Calothrix sp. The level of Calothrix was lower in sterilized E. cordifolius (38.88%) when compared with control (46.19%) and unsterilized E. cordifolius (49.69%). In control of L. articulata, Clostridium was a dominant bacterium. The proportion of Clostridium was lower in sterilized L. articulata (1.31%) when compared with control (13.72%) and unsterilized (49.02%) L. articulata. In conclusion, the results suggested that selected aquatic plants were effective in the removal of phosphate and nitrogen. Also, bacterial compositions presented in these plants were changed after sodium hypochlorite treatment. This study suggested that symbiotic bacteria might affect the removal of phosphorus and nitrogen from domestic wastewater.