Microbes-assisted phytoremediation of lead and petroleum hydrocarbons contaminated water by water hyacinth.

An experiment was carried out to explore the impact of petroleum hydrocarbons (PHs)-degrading microbial consortium (MC) on phytoremediation ability and growth of water hyacinth (WH) plants in water contaminated with lead (Pb) and PHs. Buckets (12-L capacity) were filled with water and WH plants, PHs (2,400 mg L-1) and Pb (10 mg L-1) in respective buckets. Plants were harvested after 30 days of transplanting and results showed that PHs and Pb substantially reduced the agronomic (up to 62%) and physiological (up to 49%) attributes of WH plants. However, the application of MC resulted in a substantial increase in growth (38%) and physiology (22%) of WH plants over uninoculated contaminated control. The WH + MC were able to accumulate 93% Pb and degrade/accumulate 72% of PHs as compared to initial concentration. Furthermore, combined use of WH plants and MC in co-contamination of PHs and Pb, reduced Pb and PHs contents in water by 74% and 68%, respectively, than that of initially applied concentration. Our findings suggest that the WH in combination with PHs-degrading MC could be a suitable nature-based water remediation technology for organic and inorganic contaminants and in future it can be used for decontamination of mix pollutants from water bodies.

Phytoremediation by aquatic macrophytes is a promising technique for the cleanup of environmental toxins from wastewater. To our knowledge, this is the first study reporting the integrated use of water hyacinth (WH) plants and a newly developed multi-trait microbial consortium for the simultaneous remediation of organic (i.e., petroleum hydrocarbons) and inorganic (i.e., lead) pollutants from the contaminated water. Findings of this study provide the basic but important information on the combined use of WH and microbes for remediation of mix pollution from water bodies.

Combined application of Bacillus sp. MN-54 and phosphorus improved growth and reduced lead uptake by maize in the lead-contaminated soil.

Lead (Pb) is considered an important environmental contaminant due to its considerable toxicity to living organisms. It can enter and accumulate in plant tissues and become part of the food chain. In the present study, individual and combined effects of Bacillus sp. MN-54 and phosphorus (P) on maize growth and physiology were evaluated in Pb-contaminated soil. A pristine soil was artificially contaminated with two levels of Pb (i.e., 250 and 500 mg kg-1 dry soil) and was transferred to plastic pots. Bacillus sp. MN-54 treated and untreated maize (DK-6714) seeds were planted in pots. Recommended doses of nutrients (N and K) were applied in each pot while P was applied in selective pots. Results showed that Pb stress hampered the maize growth and physiological attributes in a concentration-dependent manner, and significant reductions in seedling emergence, shoot and root lengths, fresh and dry biomasses, leaf area, chlorophyll content, rate of photosynthesis, and stomatal conductance were recorded compared with control. Application of Bacillus sp. MN-54 or P particularly in combination significantly reduced the toxic effects of Pb on maize. At higher Pb level (500 mg kg-1), the combined application effectively reduced Pb uptake up to 42.4% and 50% by shoots, 30.8% and 33.9% by roots, and 18.4% and 26.2% in available Pb content in soil after 45 days and 90 days, respectively compared with that of control. Moreover, the use of Bacillus sp. MN-54 significantly improved the P uptake by maize plants by 44.4% as compared with that of control. Our findings suggest that the combined use of Bacillus sp. MN-54 and P could be effective and helpful in improving plant growth and Pb immobilization in Pb-contaminated soil.