The Role of Plant-Associated Bacteria in Phytoremediation of Trace Metals in Contaminated Soils
01 Jan 2019-pp 69-76
TL;DR: In this article, the authors highlighted the potential of plant growth-promoting rhizobacteria (PGPR) in enhanced phytoremediation of trace metals in contaminated soils and also enlightens the modes of plant-microbe interactions.
Abstract: The ever-increasing development, industrialization, and anthropogenic activities are an indiscriminate source of heavy metal pollution in the environment These metals have negative impacts on humans, animals, and plants, thus their remediation is crucial The remediation of heavy metals from the contaminated sites using conventional methods is costly and environmentally deteriorating Phytoremediation is an eco-friendly, cost effective, and promising technique that employs various hyperaccumulator plants to remediate contaminants from the environment (soil, surface, and groundwater) However, under high metal stress conditions phytoremediation efficiency of plants is greatly hindered Plant growth-promoting rhizobacteria can enhance the efficiency of the phytoremediation process under stress conditions These bacteria efficiently convert the toxic metals into nontoxic and bioavailable forms Moreover, the plant growth-promoting rhizobacteria (PGPR) inhabit traits such as nitrogen fixation, iron sequestration, phosphate solubilization, hydrogen cyanide production, antibiotic synthesis, and 1-aminocyclopropane-1-carboxylic acid, which may enhance the plant biomass and improve plant growth, thereby assisting phytoremediation This chapter highlights the potential of PGPR in enhanced phytoremediation of trace metals in contaminated soils and also enlightens the modes of plant-microbe interactions
Citations
More filters
TL;DR: It is evidenced that A. filiculoides possess a microbiome whose representatives belong to metal-resistant species which makes the fern the source of biotechnologically useful microorganisms for remediation processes.
Abstract: The metal hyperaccumulator Azolla filiculoides is accompanied by a microbiome potentially supporting plant during exposition to heavy metals. We hypothesized that the microbiome exposition to selected heavy metals will reveal metal tolerant strains. We used Next Generation Sequencing technique to identify possible metal tolerant strains isolated from the metal-treated plant (Pb, Cd, Cr(VI), Ni, Au, Ag). The main dominants were Cyanobacteria and Proteobacteria constituting together more than 97% of all reads. Metal treatment led to changes in the composition of the microbiome and showed significantly higher richness in the Pb-, Cd- and Cr-treated plant in comparison with other (95-105 versus 36-44). In these treatments the share of subdominant Actinobacteria (0.4-0.8%), Firmicutes (0.5-0.9%) and Bacteroidetes (0.2-0.9%) were higher than in non-treated plant (respectively: 0.02, 0.2 and 0.001%) and Ni-, Au- and Ag-treatments (respectively: <0.4%, <0.2% and up to 0.2%). The exception was Au-treatment displaying the abundance 1.86% of Bacteroidetes. In addition, possible metal tolerant genera, namely: Acinetobacter, Asticcacaulis, Anabaena, Bacillus, Brevundimonas, Burkholderia, Dyella, Methyloversatilis, Rhizobium and Staphylococcus, which form the core microbiome, were recognized by combining their abundance in all samples with literature data. Additionally, the presence of known metal tolerant genera was confirmed: Mucilaginibacter, Pseudomonas, Mycobacterium, Corynebacterium, Stenotrophomonas, Clostridium, Micrococcus, Achromobacter, Geobacter, Flavobacterium, Arthrobacter and Delftia. We have evidenced that A. filiculoides possess a microbiome whose representatives belong to metal-resistant species which makes the fern the source of biotechnologically useful microorganisms for remediation processes.
22 citations
01 Jan 2021
TL;DR: In this article, the authors focused on plant-microbes interactions during phytoremediation and how such beneficial interactions lead to improved plant growth and contamination free environment, and emphasized on plant and microbes interactions.
Abstract: Environmental pollution with obnoxious contaminants is detrimental to plant growth and poses health hazards to humans and other life forms. Thus, remediation of such antagonistic environment has become a key issue for environmentalists all around the world. Phytoremediation, a cooperative association between plants and microbes, is an emerging in situ cost-effective technology and provides a viable option in the treatment of such contaminated environments. Present chapter emphasizes on plant–microbes interactions during phytoremediation and how such beneficial interactions lead to improved plant growth and contamination free environment.
10 citations
TL;DR: In this article, the authors present issues related to the possibility of using toxicological tests as a tool to monitor the progress of soil treatment contaminated with petroleum substances (TPH, PAH, Zn, Pb, Cd and Cd) in bio-phytoremediation processes.
Abstract: The article presents issues related to the possibility of using toxicological tests as a tool to monitor the progress of soil treatment contaminated with petroleum substances (TPH, PAH), Zn, Pb and Cd in bio-phytoremediation processes. In order to reduce the high content of petroleum pollutants (TPH = 56,371 mg kg−1 dry mass, PAH = 139.3 mg kg−1 dry mass), the technology of stepwise soil treatment was applied, including basic bioremediation and inoculation with biopreparations based of indigenous non-pathogenic species of bacteria, fungi and yeasts. As a result of basic bioremediation in laboratory conditions (ex-situ method), the reduction of petroleum pollutants TPH by 33.9% and PAH by 9.5% was achieved. The introduction of inoculation with biopraparation-1 prepared on the basis of non-pathogenic species of indigenous bacteria made it possible to reduce the TPH content by 86.3%, PAH by 40.3%. The use of a biopreparation-1 enriched with indigenous non-pathogenic species of fungi and yeasts in the third series of inoculation increased to an increase in the degree of biodegradation of aliphatic hydrocarbons with long carbon chains and PAH by a further 28.9%. In the next stage of soil treatment after biodegradation processes, which was characterized by an increased content of heavy metals (Zn, Pb, Cd) and naphthalene, chrysene, benzo(a)anthracene and benzo(ghi)perylene belonging to polycyclic aromatic hydrocarbons, phytoremediation with the use of Melilotus officinalis was applied. After the six-month phytoremediation process, the following was achieved: Zn content by 25.1%, Pb by 27.9%, Cd by 23.2% and TPH by 42.2% and PAH by 49.9%. The rate of removal of individual groups of hydrocarbons was in the decreasing order: C12–C18 > C6–C12 > C18–C25 > C25–C36. PAHs tended to be removed in the following order: chrysene > naphthalene > benzo(a)anthracene > benzo(ghi)perylene. The TF and BCF coefficients were calculated to assess the capacity of M. officinalis to accumulate metal in tissues, uptake from soil and transfer from roots to shoots. The values of TF translocation coefficients were, respectively, for Zn (0.44), Pb (0.12), Cd (0.40). The calculated BCF concentration factors (BCFroots > BCFshoots) show that heavy metals taken up by M. officinalis are mainly accumulated in the root tissues in the following order Zn > Pb > Cd, revealing a poor metal translocation from the root to the shoots. This process was carried out in laboratory conditions for a period of 6 months. The process of phytoremediation of contaminated soil using M. officinalis assisted with fertilization was monitored by means of toxicological tests: Microtox, Ostracodtoxkit FTM, MARA and PhytotoxkitTM. The performed phytotoxicity tests have indicated variable sensitivity of the tested plants on contaminants occurring in the studied soils, following the sequence: Lepidium sativum < Sorghum saccharatum < Sinapis alba. The sensitivity of toxicological tests was comparable and increased in the order: MARA < Ostracodtoxkit FTM < Microtox. The results of the toxicological monitoring as a function of the time of soil treatment, together with chemical analyses determining the content of toxicants in soil and biomass M. officinalis, clearly confirmed the effectiveness of the applied concept of bioremediation of soils contaminated with zinc, lead and cadmium in the presence of petroleum hydrocarbons.
10 citations