Identification of lead-resistant rhizobacteria of Carthamus tinctorius and their effects on lead absorption of Sunflower

Abstract

Aims: Using rhizobacteria as plant growth-promoting agents for improving heavymetal phytoremediation processes in contaminated soil has attracted a lot of attention mainly because of their eco-friendliness. The aim of this study was the evaluation of lead phytoremediation by Carthamus tinctorius improved with the isolated and molecularly identified lead-resistant rhizobacteria. Methods and Results: Rhizobacteria were isolated from C. tinctorius root and was identified using macroscopic and microscopic characteristics, biochemical testing and PCR. Then, the indole acetic acid production and phosphate-solubilizing activity were determined. Finally, the amount of lead in the plant was measured by atomic absorption method. Five strains of Bacillus cereus, Bacillus muralis, Bacillus sp., Pseudomonas fluorescens and Brevibacterium frigoritolerans with the ability of mineral phosphate solubilizing, high levels of indole acetic acid production and resistance to lead were isolated from the rhizosphere of C. tinctorius. The amount of produced indole acetic acid and the level of phosphate solubilizing by the isolates were 7.1-69.54 µg ml −1 and 91-147.3 µg ml −1 respectively. Lead assimilation in aerial part of safflower ranged from 925 to 2175 ppm. P. fluorescens and B. cereus strains had the highest effect on Lead assimilation with 2175 and 1862 ppm respectively. Conclusions: The results showed that different bacterial treatments influenced the rate of lead absorption by C. tinctorius exposed to lead stress. Significance and Impact of the Study: Use of rhizosphere isolates of C. tinctorius can improve phytoremediation capability and lead absorption in leadcontaminated soil.

Assessment of rhizosphere bacterial diversity and composition in a metal hyperaccumulator (Boehmeria nivea) and a nonaccumulator (Artemisia annua) in an antimony mine

“…These bacteria with higher abundance (such as Acidobacteria and Bacteroidetes ) can improve the enrichment ability and growth ability of hyperaccumulators in a heavy metal environment. In addition, the bioavailability of metal elements in rhizosphere soil is significantly correlated to the relative abundance of the plant bacterial community (Hou et al, 2017; Shahraki et al, 2021).…”

Inoculation of heavy metal resistant bacteria alleviated heavy metal-induced oxidative stress biomarkers in spinach (Spinacia oleracea L.)

“…Ramaiah and Vardanyan [ 37 ], in their study to evaluate the detoxification potential of cadmium and lead, investigated the bacteria, Alcaligenes faecalis , Bacillus pumilus , Pseudomonas aeruginosa , and Brevibacterium iodinium , which are highly resistant to mercury and can grow at 25 ppm or higher mercury concentrations, in a growth medium of 100 ppm and 72 ppm, respectively. They wereobserved to remove more than 70% of Cd and 98% of Pb within 96 h. Shahraki et al [ 38 ] found that Pseudomonas fluorescens and B. cereus strains had the greatest effect on lead assimilation at 2175 and 1862 ppm, respectively. Bilal et al [ 39 ] found that co- refinement of LHL10 and LHL06 promoted plant growth characteristics and photosynthetic activity, glutathione, catalase and superoxide dismutase activities, and decreased lipid peroxidation by increasing macronutrient uptake under high temperature and drought stress.…”