Vermiculite bio-barriers for Cu and Zn remediation: an eco-friendly approach for freshwater and sediments protection

The increase in heavy metal contamination in freshwater systems causes serious environmental problems in most industrialized countries, and the effort to find ecofriendly techniques for reducing water and sediment contamination is fundamental for environmental protection. Permeable barriers made of natural clays can be used as low-cost and eco-friendly materials for adsorbing heavy metals from water solution and thus reducing the sediment contamination. This study discusses the application of permeable barriers made of vermiculite clay for heavy metals remediation at the interface between water and sediments and investigates the possibility to increase their efficiency by loading the vermiculite surface with a microbial biofilm of Pseudomonas putida, which is well known to be a heavy metal accumulator. Some batch assays were performed to verify the uptake capacity of two systems and their adsorption kinetics, and the results indicated that the vermiculite bio-barrier system had a higher removal capacity than the vermiculite barrier (?34.4 and 22.8 % for Cu and Zn, respectively). Moreover, the presence of P. putida biofilm strongly contributed to fasten the kinetics of metals adsorption onto vermiculite sheets. In open-system conditions, the presence of a vermiculite barrier at the interface between water and sediment could reduce the sediment contamination up to 20 and 23 % for Cu and Zn, respectively, highlighting the efficiency of these eco-friendly materials for environmental applications. Nevertheless, the contribution of microbial biofilm in open-system setup should be optimized, and some important considerations about biofilm attachment in a continuous-flow system have been discussed.This work has been produced thanks to the collaboration of Dip.SA (University of Bologna) and IBB (University of Minho). A particular acknowledgment is due to Dr. E. Rosales. The work was partially financed by the FCT Strategic Project Pest-OE/EQB/LA0023 and the Project ‘‘BioEnv—Biotechnology and Bioengineering for a sustainable world,’’ co-funded by the Programa Operacional Regional do Norte (ON.2–O Novo Norte), QREN, FEDER

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Not AvailableTo elucidate the bio-diversity of plant growth promoting wheat associated acidotolerant bacteria from Southern hills zone of India. In this study, the diversity and phylogenetic relationships among plant growth-promoting (PGP) bacteria isolated from the wheat phyllosphere, rhizosphere and endophytic growing in acidic soils of Tamilnadu (pH 3.8-6.8) were investigated. Bacterial diversity was analysed through amplified ribosomal DNA restriction analysis (ARDRA) using three restriction enzymes Alu I, Hae III and Msp I which led to the grouping of 135 isolates into 33 clusters at >75% similarity index. 16S rRNA gene based phylogenetic analysis, revealed that isolates belonged to 4 phyla namely actinobacteria (4%), bacteroidetes (4%), firmicutes (52%) and proteobacteria (40%) with 33 distinct species of 13 genera. In vitro for plant growth promotion (PGP) traits were done at different pH which included solubilization of phosphorus, potassium and zinc, production of ammonia, hydrogen cyanide, indole-3-acetic acid and siderophore, nitrogen fixation, 1-aminocyclopropane-1-carboxylate deaminase activity and bio-control against Fusarium graminerum, Rhizoctonia solani and Macrophomina phaseoli. Acidotolerant isolates may have application as inoculants plant growth promoting and bio-control agents in crops growing under acidic condition.Not Availabl

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Not AvailableThe diversity of plant growth promoting bacteria was investigated from wheat growing in different sites in central zone of India. Epiphytic, endophytic and rhizospheric bacteria were isolated using different growth medium. Bacterial diversity was analysed through amplified ribosomal DNA restriction analysis (ARDRA) using three restriction enzymes Alu I, Hae III, and Msp I which led to the grouping of 348 isolates into 24-29 clusters at >75% similarity index. 16S rRNA gene based phylogenetic analysis, revealed that 134 strains belonged to three phyla namely actinobacteria, firmicutes and proteobacteria with 38 distinct species of 17 genera. Bacillus and Pseudomonas were dominant in rhizosphere while Methylobacterium were in phyllosphere. Endophytic niche specific bacteria were identified as Delftia and Micrococcus. Sampling of different sites showed variation in diversity indices. In vitro plant growth promoting activities of bacteria exposed more than three beneficial traits which may act independently or concurrently. Phosphate solubilization and siderophores production are the predominant traits exhibited by these microbes. The many species of genera Bacillus, Exiguobacterium, Micrococcus, Pseudomonas and Psychrobacter showed antagonistic properties against fungal pathogens Fusarium graminerum, Rhizoctonia solani and Macrophomina phaseoli. These promising isolates showing a range of useful plant growth promoting attributes insist to be explored for agricultural applications.Not Availabl