The silver lining of antibiotic resistance: Bacterial-mediated reduction of tetracycline plant stress via antibiotrophy

Abstract

The reuse of water using effluents containing antibiotics from anthropogenic activities has been mainly linked to the development of antibiotic resistance. However, we report that the development of bacterial tolerance promotes plant growth. In the present study, we aimed to evaluate the efficiency of inoculation of a new antibiotic-degrading bacterium, Erwinia strain S9, in augmenting the tolerance of pea (Pisum sativum L.) plants to tetracycline (TET) (10 and 20 mg/L). Physiological parameters such as tissue elongation and biomass, as well as relative water content, were remarkably lower in plants exposed to TET than in the control. The inhibitory effects of TET were associated with reduced CO2 assimilation, stomatal conductance, transpiration, dark respiration, and light saturation point (LSP). High concentrations of TET-induced oxidative stress are attested by the overproduction of superoxide radicals (O2•−), hydrogen peroxide (H2O2), and hydroxyl radicals (HO•), resulting in increased malondialdehyde content and cell death. The high activity of antioxidant enzymes such as catalase, ascorbate peroxidase, and guaiacol peroxidase validated the proposed mechanism. Under TET stress conditions, supplementation with Erwinia strain S9 was beneficial to pea plants through osmotic adjustment, increased nutrient uptake, gas exchange optimization, and increased antioxidant activities. Its presence not only ensures plant survival and growth during antibiotic stress but also degrades TET via significant antibiotrophy. This strategy is a cost-effective environmental chemical engineering tool that can be used to depollute wastewater or to improve crop resistance in rhizofiltration treatment when treated wastewater is reused for irrigation.