Isolation of the PCB-degrading bacteriaMesorhizobiumsp. ZY1 and its combined remediation withAstragalus sinicusL. for contaminated soil

Abstract

A bacterial strain ZY1 capable of utilizing PCBs as its carbon source was isolated from the root nodules of Chinese milk vetch (Astragalus sinicus L.). The strain was identified as Mesorhizobium sp. according to its physiological-biochemical properties and the analysis of its 16S rRNA gene sequence. When the initial OD600 was 0.15, 62.7% of 15 mg L(-1) 3,3',4,4'-TCB in a liquid culture was degraded by Mesorhizobium sp. ZY1 within 10 days. Mesorhizobium sp. ZY1 also greatly increased the biotransformation of soil PCBs. Pot experiments indicated that the soil PCB concentrations of a single incubation of strain ZY1 (R) and a single planting of A. sinicus (P) decreased by 20.5% and 23.0%, respectively, and the concentration of PCBs in soil treated with A. sinicus and strain ZY1 decreased by 53.1%. We also observed that A. sinicus-Mesorhizobium sp. ZY1 treatment (PR) improved plant biomass and the concentration of PCBs in plants compared with a single A. sinicus planting treatment (P). The results suggest that the synergistic association between A. sinicus and PCBs-degrading Mesorhizobium sp. ZY1 can stimulate the phytoextraction of PCBs and the rhizosphere microflora to degrade PCBs, and might be a promising bioremediation strategy for PCB-contaminated soil.

Assessing the Spatial Distribution of Soil PAHs and their Relationship with Anthropogenic Activities at a National Scale

“…Soil is an important indicator of environmental pollution in PAHs, which can be a long-term reservoir of organic compounds [31][32][33]. The state of soil PAH pollution has received increasingly more attention in recent years [34][35][36].…”

Characterization of the belowground microbial community in a poplar-assisted bioremediation strategy for restoring a multi-contaminated soil

“…xenobiotic degradation ( Figure 3C), in the Rhizosphere and Bulk Soil than in the Control [29,30,31,32,33]. On the other hand, the Control microbial community was quite different from that of the planted plots and some genera such as Nitrososphaera (Archaea), Nocardioides (Actinobacteria) and Stereoidobacter (Gammaproteobacteria) were signi cantly more abundant than in the other condtions.…”

Rhizobia and their Bio-Partners as Novel Drivers for Functional Remediation in Contaminated Soils

“…Inoculation with active ZY1 significantly degraded PCBs compared with control (P < 0.05). A remarkable enhancement in the total PCB degradation was also observed (57.6%) in the active inoculants treatment (Teng et al, 2016). Teng et al, (2016), reported that the bacterial inoculation significantly enhanced the numbers of bacteria able to use PCBs as the sole carbon source in the soil compared with control ( Fig.…”

“…With the degradation of tetra-CB, the proportion of tri-CB increased. The percentage of di-CB increased to 36.7% in the first 7 days and then decreased to 14.7 % at the 28th day (Teng et al, 2016). Teng et al, (2016), reported that the combined remediation effects of planting A. sinicus inoculated with Mesorhizobium sp.…”

“…The exact mechanisms involved in this process are not revealed and further work is required to further elucidate the processes involved . Teng et al, (2016), reported that the biodegradation of 3,3,4,4-TCB (PCB77) by strain ZY1 in a liquid culture is presented in Figure 8. After 10 days of incubation, the concentration of PCB77 decreased in both treatments.…”