Metal Resistant Enterobacter cloacae ZA14 Enhanced Seedling Vigor and Metal Tolerance through Improved Growth, Physiology and Antioxidants in Tomato (Solanum lycopersicum) Irrigated with Textile Effluents

Abstract

The presence of toxic heavy metals and dyes in textile wastewater is a serious problem contaminating vegetables by irrigation. This contaminated food upon consumption undermines human health and is lethal for human life. The endophytic bacteria have the ability to degrade textile dyes and remediate heavy metals. The purpose of the present investigation was to evaluate useful concentration levels of textile wastewater (TWW) for irrigation in combination with the endophytic bacterium Enterobacter cloacae ZA14 to remediate heavy metals for improving growth of the tomato (Solanum lycopersicum) plant. The tomato seedlings showed inhibited germination (52%); suppressed root length (55%) and shoot length (53%); declined RWC (47%); lowest CSI (34%); reduced MSI (32%); increased accumulation of heavy metals Cr, Pb, and Cd in roots and shoots; with decreased metal tolerance index; and rise in production of total thiols (57%) at use of 100% TWW without bacterial application. On the contrary, the supplementation of endophytic bacterium ZA14 showed improved germination (100%), a decline of 3 and 5% in root and shoot length respectively, increased CSI (13%), decrease in MSI (6%), reduced bioaccumulation of Cr (root 30 and shoot 56%), Pb (root 58 and shoot 65%), and Cd (root 21 and shoot 58%), total thiols (76%), when irrigated with 25% TWW. Hence, it is concluded that the irrigation with 25% TWW, along with the application of Enterobacter cloacae ZA14, may improve the growth of tomato by mitigating the phytotoxicity of dyes and heavy metals from textile wastewater.