Effect of copper-resistant<i>Stenotrophomonas maltophilia</i>on maize (<i>Zea mays</i>) growth, physiological properties, and copper accumulation: potential for phytoremediation into biofortification

Abstract

In this study, Cu-tolerant PGP bacteria were isolated from the contaminated soils of Tapi (Surat, Gujarat, India). From a set of 118 bacteria isolated from the contaminated soil, the isolate RBTS7 was found to be efficient in tolerating 0.3 g (w/v) Cu. The isolate was identified as <i>Stenotrophomonas maltophilia</i>, based on biochemical and 16S rRNA gene sequencing. Further, the isolate was also found to produce indole acetic acid (140 µg/ml) and siderophore, and solubilize potassium. Inoculation study was carried out in the presence and absence of Cu in the greenhouse. The results revealed that <i>S. maltophilia</i> enhanced plant growth and biomasses compared to control. In addition to plant growth attributes, the isolate also enhanced chlorophyll <i>a</i> and <i>b</i> (434.1 and 496.7%) contents and antioxidant properties such as proline (168.2%), total phenolic compounds (33.5%), and ascorbic acid oxidase (62.3%) compared to control with Cu and without Cu. Inoculation of <i>S. maltophilia</i> + Cu enhanced the uptake of Cu in maize root (77.4%) and stem (112.0%) compared to Cu-stressed control. The results clearly indicated the inoculation of <i>S. maltophilia</i> reduced the toxicity of Cu and in turn enhanced the plant growth and mobilization of Cu to the plant parts.