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

Abstract

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.

Cultural techniques capture diverse phosphate-solubilizing bacteria in rock phosphate-enriched habitats

“…Future investigations should incorporate diverse cultivation media and techniques to reduce potential biases and capture bacterial diversity closer to that observed in natural habitats (Chen and Liu, 2019). Additionally, investigations 10.3389/fmicb.2024.1280848 Frontiers in Microbiology 14 frontiersin.org on bacterial taxonomic diversity, community structure, and functions in the mining area [using sequencing and phylogenetic analysis of the 16S rRNA gene combined with OMICS technologies (Mghazli et al, 2021)] would be relevant for identifying taxa and functions involved in P cycling in native P mining environments. Also, further greenhouse and field studies will be essential in the future to test the dual use of mineral nutrient and microbial resources (individually or in polymicrobial formulations, multi-species, and pluri-functional) for agronomic purposes.…”

Potentialities of Medicinal Indigenous taxa for accumulation of macro- and micro elements increasing nearby Abu-Tartur phosphate mining ore, Egypt

“…In general, the soils near mining sites, where wild plants thrive, are low in macro-nutrient levels, except for phosphorus, which worked in conjunction with calcium (Penn & Camberato 2019), Sulphur, potassium, and other micro-elements as indicated in the current data. Most of the other phosphate mining in other nations differs in terms of the abiotic conditions and the vegetation it uses (Xiao et al, 2008;Kratz et al, 2016;Mghazli et al, 2021). Numerous mining nations, including South Africa, Spain, Morocco, Mexico, and Ghana, are seeing a decline in soil quality because of trace metal poisoning from mine tailing dumps that have not been remedied (Lu et al, 2019;Cao et al, 2022;Tibane & Mamba, 2022).…”

Characterization of plant growth promoting activities of indigenous bacteria of phosphate mine wastes, a first step toward revegetation

“…Five subsamples were collected from different random locations, then were processed in the laboratory within a week of sampling. The physicochemical properties of these phosphate tailings were identified and are detailed in Mghazli et al (2021) and Supplementary Table 1 .…”

“…In a previous study ( Mghazli et al, 2021 ), the bacterial diversity of phosphate wastes was characterized using Illumina MiSeq sequencing. The V4 region of the 16S rRNA gene sequences was targeted and revealed a huge number of sequences, totaling 8 million raw reads.…”