RESUMO
AIMS: The current study was aimed to evaluate the beneficial effects and bioremediation potential of a Cd-tolerant bacterial strain, Serratia sp. CP-13, on the physiological and biochemical functions of Linum usitatissimum L., under Cd stress. METHODS AND RESULTS: The bacterial strain was isolated from the wastewater collection point of Chakera, Faisalabad, Pakistan, as this place contains industrial wastewater of the Faisalabad region. The Serratia sp. CP-13, identified through 16S rRNA gene sequence analysis, exhibited a significant phyto-beneficial potential in terms of in vitro inorganic phosphate solubilization, indole-3-acetic acid production and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Effects of Serratia sp. CP-13 inoculation on L. usitatissimum were evaluated by growing the plants in CdCl2 (0, 5 or 10 mg kg-1 dry soil)-spiked soil. Without inoculation of Serratia sp. CP-13, Cd stress significantly reduced the plant biomass as well as the quantity of proteins and photosynthetic pigments due to enhanced H2 O2 , malondialdehyde (MDA) contents and impaired nutrient homeostasis. Subsequently, Serratia sp. CP-13 increased the plant fresh and dry biomass, plant antioxidation capacity, whereas it decreased the lipid peroxidation under Cd stress. In parallel, Serratia sp. inoculation assisted the Cd-stressed plants to maintain an optimum level of nutrients (K, Ca, P, Mg, Fe and Mn). CONCLUSIONS: The isolated bacterial strain (Serratia sp. CP-13) when applied to Cd-stressed L. usitatissimum inhibited the Cd uptake, reduced Cd-induced lipid peroxidation, maintained the optimum level of nutrients and thereby, enhanced L. usitatissimum growth. The analysis of bio-concentration and translocation factor revealed that L. usitatissimum with Serratia sp. CP-13 inoculation sequestered Cd in plant rhizospheric zone. SIGNIFICANCE AND IMPACT OF THE STUDY: Serratia sp. CP-13 inoculation is a potential candidate for the development of low Cd-accumulating linseed and could be used for phytostabilization of Cd-contaminated rhizosphere/soil colloids.