title: Screening and Evaluation of the Bioremediation Potential of Cu/Zn-Resistant, AutochthonousAcinetobactersp. FQ-44 fromSonchus oleraceusL.
abstract: The quest for new, promising and indigenous plant growth-promoting rhizobacteria and a deeper understanding of their relationship with plants are important considerations in the improvement of phytoremediation. This study focuses on the screening of plant beneficial Cu/Zn-resistant strains and assessment of their bioremediation potential (metal solubilization/tolerance/biosorption and effects on growth ofBrassica napusseedlings) to identify suitable rhizobacteria and examine their roles in microbes-assisted phytoremediation. Sixty Cu/Zn-resistant rhizobacteria were initially isolated fromSonchus oleraceusgrown at a multi-metal-polluted site in Shanghai, China. From these strains, 19 isolates that were all resistant to 300 mg⋅L-1Cu as well as 300 mg⋅L-1Zn, and could simultaneously grow on Dworkin-Foster salt minimal medium containing 1-aminocyclopropane-1-carboxylic acid were preliminarily selected. Of those 19 isolates, 10 isolates with superior plant growth-promoting properties (indole-3-acetic acid production, siderophore production, and insoluble phosphate solubilization) were secondly chosen and further evaluated to identify those with the highest bioremediation potential and capacity for bioaugmentation. Strain S44, identified asAcinetobactersp. FQ-44 based on 16S rDNA sequencing, was specifically chosen as the most favorable strain owing to its strong capabilities to (1) promote the growth of rape seedlings (significantly increased root length, shoot length, and fresh weight by 92.60%, 31.00%, and 41.96%, respectively) under gnotobiotic conditions; (2) tolerate up to 1000 mg⋅L-1Cu and 800 mg⋅L-1Zn; (3) mobilize the highest concentrations of water-soluble Cu, Zn, Pb, and Fe (16.99, 0.98, 0.08, and 3.03 mg⋅L-1, respectively); and (4) adsorb the greatest quantities of Cu and Zn (7.53 and 6.61 mg⋅g-1dry cell, respectively). Our findings suggest thatAcinetobactersp. FQ-44 could be exploited for bacteria-assisted phytoextraction. Moreover, the present study provides a comprehensive method for the screening of rhizobacteria for phytoremediation of multi-metal-polluted soils, especially those sewage sludge-amended soils contaminated with Cu/Zn.
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Zhengqiu
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Xiangrong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Environmental Science and Engineering, Fudan University Shanghai, China.
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Liu
keywords: Acinetobacter; Cu/Zn-resistant; Sonchus oleraceus; bioremediation; plant-growth-promoting rhizobacteria