Isolation, screening and identification of Cu, Zn and Pb resistant plant growth-promoting bacteria from Le’an River-Poyang Lake Wetland

Abstract:

[Background] Plant growth-promoting bacteria (PGPB) have good potential in assisting phytoremediation of heavy metal pollution due to their advantages in promoting the growth and heavy metal-resistance of plants. In heavy metal-contaminated soils, indigenous PGPB can better colonize and exert their plant growth-promoting abilities. [Objective] Our aim is to isolate the indigenous heavy mental-resistant PGPB from the Le’an River-Poyang Lake Wetland, which has been polluted by acid mine drainage for many years, thus to provide superior microbial resources for bacterial assisted phytoremediation of heavy metal polluted wetland soil. [Methods] Cu, Zn and Pb-resistant strains were isolated from heavy metal polluted wetland soils and water in Dai cun, which is located in Le’an River. The plant growth-promoting characteristics (IAA (Indole acetic acid), phosphate solubilization, siderophore and ACC (1-aminocyclopropane-1-carboxylic acid) deaminase activity) of the studied isolates were measured, and the isolates with good growth-promoting characteristics were selected and identified using 16S rRNA gene sequencing. The resistant characteristics (heavy metal, antibiotics, acid and alkali, salt) of the selected strains were also determined. [Results] A total of 22 isolates were able to grow in the presence of Cu 50 mg/L, Zn 400?mg/L and Pb 800 mg/L. Among them, 10 strains showed good plant growth-promoting characteristics. According to 16S rRNA gene sequencing, 4 strains belonged to the genus Ralstonia, 3 strains belonging to the genus Burkholderia and the other 3 strains belonged to the genera Cupriavidus, Stenotrophomonas and Novosphingobium, repectively. The numerical classification based on bacterial resistant characteristics was mostly consistent with their phylogenetic position. [Conclusion] The isolation and identification of multiple heavy mental-resistant PGPB could provide good microbial resources for in situ remediation of heavy metal contaminated soils.

Key words:Heavy metal pollution, Phyto-microbial remediation, PGPB, Resistant strain