scholarly journals Description of Microbial Communities of Phosphate Mine Wastes in Morocco, a Semi-Arid Climate, Using High-Throughput Sequencing and Functional Prediction

2021 ◽  
Vol 12 ◽  
Author(s):  
Najoua Mghazli ◽  
Laila Sbabou ◽  
Rachid Hakkou ◽  
Ahmed Ouhammou ◽  
Mariam El Adnani ◽  
...  

Soil microbiota are vital for successful revegetation, as they play a critical role in nutrient cycles, soil functions, and plant growth and health. A rehabilitation scenario of the abandoned Kettara mine (Morocco) includes covering acidic tailings with alkaline phosphate mine wastes to limit water infiltration and hence acid mine drainage. Revegetation of phosphate wastes is the final step to this rehabilitation plan. However, revegetation is hard on this type of waste in semi-arid areas and only a few plants managed to grow naturally after 5 years on the store-and-release cover. As we know that belowground biodiversity is a key component for aboveground functioning, we sought to know if any structural problem in phosphate waste communities could explain the almost absence of plants. To test this hypothesis, bacterial and archaeal communities present in these wastes were assessed by 16S rRNA metabarcoding. Exploration of taxonomic composition revealed a quite diversified community assigned to 19 Bacterial and two Archaeal phyla, similar to other studies, that do not appear to raise any particular issues of structural problems. The dominant sequences belonged to Proteobacteria, Bacteroidetes, Actinobacteria, and Gemmatimonadetes and to the genera Massilia, Sphingomonas, and Adhaeribacter. LEfSe analysis identified 19 key genera, and metagenomic functional prediction revealed a broader phylogenetic range of taxa than expected, with all identified genera possessing at least one plant growth-promoting trait. Around 47% of the sequences were also related to genera possessing strains that facilitate plant development under biotic and environmental stress conditions, such as drought and heat.

2017 ◽  
Vol 54 (1) ◽  
pp. 102-116 ◽  
Author(s):  
Jihane Knidiri ◽  
Bruno Bussière ◽  
Rachid Hakkou ◽  
Bruno Bossé ◽  
Abdelkabir Maqsoud ◽  
...  

A field study was conducted at the Kettara mine site located in arid climatic conditions in Morocco. The goal was to assess the performance of an inclined store-and-release (SR) cover made with phosphate mine wastes to reduce water infiltration and control acid mine drainage (AMD). The SR cover was constructed using phosphate mine wastes (0.8 m) placed over a capillary break layer (CBL) made of coarse-grained materials. The SR cover had a slope inclination of 14.5°. The cover performance was monitored for a period of 1 year under natural and artificial conditions representing important rainfall events for the climatic conditions at the Kettara mine site. Performance was monitored using volumetric lysimeters, suction sensors, and volumetric water content sensors installed at four stations and at different depths. Under natural climatic conditions, the inclined SR cover limited water percolation by diverting and releasing water to the atmosphere through evaporation. However, the cover was unable to store and divert all the water at a precipitation rate >100 mm in 48 h, and percolation was observed in the lysimeters. Nevertheless, the results confirmed the suitability of phosphate mine wastes as cover material for a 31.5 m inclined (≈ 14.5°) SR cover placed over the Kettara mine wastes in natural climatic conditions and for precipitation events <100 mm in 48 h.


2015 ◽  
Vol 52 (9) ◽  
pp. 1255-1269 ◽  
Author(s):  
Bruno Bossé ◽  
Bruno Bussière ◽  
Rachid Hakkou ◽  
Abdelkabir Maqsoud ◽  
Mostafa Benzaazoua

A field investigation was conducted to evaluate the effectiveness of store-and-release (SR) covers made with different phosphate mine wastes in reducing water infiltration (system inclination and surface runoff were neglected) and controlling acid rock drainage (ARD) generation. Four instrumented experimental cells were constructed with different SR layer configurations (two thicknesses and three materials) placed over a capillary break layer. To assess the hydrogeological behaviour of these cover systems, volumetric water content, matric suction, and meteorological monitoring time trends were studied for a period of 1.5 years under actual and extreme conditions typical of an arid climate. Under natural climatic conditions, all net infiltration was released to the atmosphere by the physical process of evaporation (regardless of SR layer thickness and type). Although high surface matric suction (>3000 kPa) decreased the evaporation rate (or release capacity) during the drying period, field tests showed that the studied scenarios limited deep water infiltration even under extreme rainfall events. The release capacity of the SR layer was slightly lower for cover systems made with the finer-grained mine waste (phosphate limestone tailings). This study showed that, for a one-dimensional (1D) condition, the tested phosphate mine wastes have the appropriate hydrogeological properties to be used as components of SR covers under conditions at the Kettara mine site, located near Marrakech, Morocco.


2021 ◽  
Vol 79 (1) ◽  
Author(s):  
Chimdi M. Kalu ◽  
Henry J. O. Ogola ◽  
Ramganesh Selvarajan ◽  
Memory Tekere ◽  
Khayalethu Ntushelo

AbstractDespite root microecology playing critical role in plant growth and fidelity, relatively few studies have focused on the link between the microbial communities and root metabolome in the aquatic macrophytes under heavy metal (HM) pollution. Using high-throughput metagenomic sequencing, targeted metabolomics and community-level physiological profile analyses, we investigated the symbiotic associations between Phragmites australis with rhizospheric bacterial communities under differing acid mine drainage (AMD) pollution. Results indicated that AMD pollution and root localization significantly affected root metabolome profiles. Higher accumulation of adenosine monophosphate, inosine, methionine, carnitine and dimethylglycine were observed in the rhizosphere under AMD than non-AMD habitat. Overall, the bacterial diversity and richness, and functional (metabolic) diversity were lower under high-AMD pollution. While non-AMD site was enriched with members of phylum Firmicutes, Proteobacteria were the most abundant taxa in the rhizosphere and endosphere under AMD-polluted sites. Further, plant growth promoting rhizobacteria (Rhizobium, Delftia, Bradyrhizobium, and Mesorhizobium) and metal-tolerant bacteria (Bacillus, Arthrobacter, Massilia and Methylocystis) were most abundant in AMD-polluted than non-AMD habitat. Finally, pH, TDS (total dissolved solids), Cu, Cr, Fe, and Zn content were the key environmental factors that strongly contributed to the spatial perturbation of rhizospheric metabolites, proteobacterial and acidobacterial taxa. Overall, the study linked the differential endospheric and rhizospheric bacterial community and metabolite profiles in P. australis under AMD environment and provided insights into HM adaptability and phytoremediation potential.


2021 ◽  
Vol 13 (5) ◽  
pp. 2432
Author(s):  
Anna Makarova ◽  
Elena Nikulina ◽  
Tatiana Avdeenkova ◽  
Ksenia Pishaeva

Heavy metals are among the most widespread pollutants in soil. Phytoextraction technology is used to solve the problem of multi-metal-contaminated soil. The efficiency of this process can be increased by introducing various amendments. A soil amendment is any material added to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration, and structure. Some chemical amendments for enhanced phytoextraction, such as amino polycarboxylates chelators, can be hazardous to the environment and perform poorly at pH > 8. The effect of the potassium salt of hydroxyethylidene diphosphonic acid (K2HEDP), plant growth regulators (PGRs), and iron chelate alone and in combination on the phytoextraction by Trifolium repens L. seedlings of Cd, Ni, and Cu was studied in this work. K2HEDP works in a wider pH range. The results of this study confirmed that amino polycarboxylate chelators, with the sodium salt of ethylene diamine tetraacetic acid (Na2EDTA) as an example, have a pronounced negative effect on the growth and development (organ mass) of Trifolium repens L. seedlings. K2HEDP, proposed by the authors instead of Na2EDTA, produced a pronounced positive effect on plant growth and development, which was further enhanced by the use of PGRs and with iron chelates. However, it should be noted that K2HEDP showed significantly lower efficiency in trials on the Trifolium repens L. seedlings. The highest was the efficiency of K2HEDP with PGRs and iron chelates for the phytoextraction of Cd.


Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 713
Author(s):  
Muna Ali Abdalla ◽  
Fengjie Li ◽  
Arlette Wenzel-Storjohann ◽  
Saad Sulieman ◽  
Deniz Tasdemir ◽  
...  

The main objective of the present study was to assess the effects of sulfur (S) nutrition on plant growth, overall quality, secondary metabolites, and antibacterial and radical scavenging activities of hydroponically grown lettuce cultivars. Three lettuce cultivars, namely, Pazmanea RZ (green butterhead, V1), Hawking RZ (green multi-leaf lettuce, V2), and Barlach RZ (red multi-leaf, V3) were subjected to two S-treatments in the form of magnesium sulfate (+S) or magnesium chloride (−S). Significant differences were observed under −S treatments, especially among V1 and V2 lettuce cultivars. These responses were reflected in the yield, levels of macro- and micro-nutrients, water-soluble sugars, and free inorganic anions. In comparison with the green cultivars (V1 and V2), the red-V3 cultivar revealed a greater acclimation to S starvation, as evidenced by relative higher plant growth. In contrast, the green cultivars showed higher capabilities in production and superior quality attributes under +S condition. As for secondary metabolites, sixteen compounds (e.g., sesquiterpene lactones, caffeoyl derivatives, caffeic acid hexose, 5-caffeoylquinic acid (5-OCQA), quercetin and luteolin glucoside derivatives) were annotated in all three cultivars with the aid of HPLC-DAD-MS-based untargeted metabolomics. Sesquiterpene lactone lactucin and anthocyanin cyanidin 3-O-galactoside were only detected in V1 and V3 cultivars, respectively. Based on the analyses, the V3 cultivar was the most potent radical scavenger, while V1 and V2 cultivars exhibited antibacterial activity against Staphylococcus aureus in response to S provision. Our study emphasizes the critical role of S nutrition in plant growth, acclimation, and nutritional quality. The judicious-S application can be adopted as a promising antimicrobial prototype for medical applications.


2014 ◽  
Vol 45 (4) ◽  
pp. 176 ◽  
Author(s):  
Mario Pirastru ◽  
Marcello Niedda ◽  
Mirko Castellini

Many hillslopes covered with maquis in the semi-arid Mediterranean environment have been cleared in recent decades. There is little information on what effect this has on the hydrology of the soil. We compared the hydraulic properties of the soil and the subsurface hydrological dynamics on two adjacent sites on a hillslope. One site was covered with maquis, the other with grass. The grass started to grow some 10 years ago, after the maquis had been cleared and the soil had been ploughed. Our study found that the hydraulic properties and the hydrological dynamics of the maquis and the grassed soil differed greatly. The grassed soil had less organic matter and higher apparent density than did the soil covered in maquis. Moreover, the maquis soil retained more water than the grassed soil in the tension range from saturation to 50 cm of water. Infiltration tests performed in summer and in winter indicated that the field saturated hydraulic conductivity (K<sub>fs</sub>) of the maquis soil was higher than that of the grassy soil. However the data showed that the K<sub>fs</sub> of the two soils changed with the season. In the maquis soil the K<sub>fs</sub> increased from summer to winter. This was assumed to be due to water flowing more efficiently through wet soil. By contrast, in the grassy soil the K<sub>fs</sub> decreased from summer to winter. This was because the desiccation cracks closed in the wet soil. As result, the influence of the land use change was clear from the K<sub>fs</sub> measurements in winter, but less so from those in the summer. Changes in land use altered the dynamics of the infiltration, subsurface drainage and soil water storage of the soil. The maquis soil profile never saturated completely, and only short-lived, event based perched water tables were observed. By contrast, soil saturation and a shallow water table were observed in the grass covered site throughout the wet season. The differences were assumed to be due to the high canopy interception of the maquis cover, and to the macropores in the grassed soil being destroyed after the maquis had been cleared and the soil ploughed. The results of this work are helpful for predicting the changes in the hydraulic properties of the soil and in the near-surface hydrological processes in similar Mediterranean environments where the natural vegetation has been cleared. These changes must be taken into consideration when developing rainfall-runoff models for flood forecasting and water yield evaluation.


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