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Composition of proliferated community. Top figure (a) depicts a PCoA ordination of community composition based on weighted UniFrac similarity metric. Blue dots are natural samples, and pink dots are post-mining samples. The ellipses represent 95 % confidence intervals, the bottom figure (b) depicts a bar plot of phyla relative abundance ( %) in natural and post-mining biocrusts.
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Biological soil crusts (biocrusts) are key contributors to desert ecosystem functions, therefore, biocrust restoration following mechanical disturbances is imperative. In the Negev Desert hyperarid regions, phosphate mining has been practiced for over 60 years, destroying soil habitats and fragmenting the landscape. In this study, we selected one m...
Citations
... In extractive processes such as open-cut and strip mining, it is common practice to remove topsoil that harbors seeds, nutrients, and microorganisms. Large-scale mining activities break and bury biocrust organisms, resulting in changed biocrust communities (Gabay et al., 2023) Additionally, these activities result in intense dust emissions that can lead to pathogen exposure, like Valley fever. Construction, mining, and agricultural occupations are at high risk of Valley fever exposure in endemic areas. ...
Biological soil crusts (or biocrust) are diminutive soil communities with ecological functions disproportionate to their size. These communities are composed of lichens, bryophytes, cyanobacteria, fungi, liverworts, and other microorganisms. Creating stabilizing matrices, these microorganisms interact with soil surface minerals thereby enhancing soil quality by redistributing nutrients and reducing erosion by containment of soil particles. Climatic stressors and anthropogenic disturbances reduce the cover, abundance, and functions of these communities leading to an increase of aeolian dust, invasive plant establishment, reduction of water retention in the environment, and overall poor soil condition. Drylands are the most degraded terrestrial ecosystems on the globe and support a disproportionately large human population. Restoration of biocrust communities in semi‐arid and arid ecosystems benefits ecosystem health while decreasing dust emissions. Dust abatement can improve human health directly but also indirectly by reducing pathogenic microbe load circulating in the ambient air. We hypothesize that biocrusts not only reduce pathogen load in the air column but also inhibit the proliferation of certain pathogenic microbes in the soil. We provide a review of mechanisms by which healthy biocrusts in dryland systems may reduce soil‐borne pathogens that impact human health. Ecologically sustainable mitigation strategies of biocrust restoration will not only improve soil conditions but could also reduce human exposure to soil‐borne pathogens.
... Mining waste, particularly heavy metals, can induce stress in bacteria, leading to hypermutation and increased antibiotic resistance. 10,11 In this study, the flat parts of the mine were used for livestock grazing. The presence of grazing animals also affects the soil physicochemical properties, microbial communities as well as the spread of antibiotic resistance genes. ...
Antibiotic resistant bacteria are present in various environments and are concerning for public health. Antibiotic resistance genes in soil may proliferate throughout different ecosystems and be acquired by pathogens that pose health risks to humans and animals. This study investigated the antibiotic resistance of cultivable bacteria isolated from livestock-exposed and unexposed areas in a former perlite mining area in the Fa-La-Mee Mountain range, Lopburi, Thailand. Soil samples were collected in five different locations. Soil bacteria were isolated and tested for susceptibility against seven antibiotics, followed by 16S rRNA gene-based identification. A total of 56 bacterial isolates were isolated from the perlite-rich soil samples, including 34 isolates from the livestock-exposed areas and 22 isolates from the unexposed areas. Most of the isolates were resistant to cefepime (26.5% in exposed areas and 22.7% in unexposed areas) and ampicillin (23.5% in exposed areas and 22.7% in unexposed areas). 16S rRNA gene sequences revealed that most of the resistant bacteria isolated from perlite-rich soil were Bacillus spp. A multidrug-resistant isolate of Bacillus cereus resistant to ampicillin, trimethoprim/ sulfamethoxazole, and cefepime was found in a livestock-unexposed area. The majority of the culturable antibiotic-resistant bacteria isolated from perlite-rich soil were cefepime-resistant Bacillus. Interestingly, the pattern of antibiotic resistance in exposed and unexposed areas was not different, which indicated that antibiotic resistance in perlite-rich soil is likely caused by other factors, such as physicochemical characteristics and/or the microbial population of the soil rather than by antibiotics used in livestock husbandry.
... CCA was performed using filtered datasets that only represented taxa occurring at least five times in 25% of the samples. This filtering step was included to focus the analysis of beta diversity on the most robust and abundant taxa, thereby reducing the introduction of noise and potential biases by rare or spurious ASVs (e.g., Gabay et al., 2023;Pombubpa et al., 2020). CCA was then conducted at the order level to identify key environmental variables that drive the community structure of bacteria and fungi biocrusts across serpentine (sites 1, 3, 5, 7, 9, 11, 13, and 15) and non-serpentine (sites 2, 4, 6, 8, 10, 12, 14, and 16) localities using CANOCO software for windows, v.4.5 (Ter Braak & Smilauer, 2002). ...
Serpentine soils are characterized by nutrient imbalances and high levels of potentially toxic metals (PTMs). These soils host depauperate plant communities of species with specialized adaptations. Initial studies showed that South African serpentine soils harbor distinct biocrust algal and cyanobacterial species compared to adjacent non-serpentine soils, with these communities further differing based on high and low precipitation levels. Here, we investigated the bacterial and fungal diversity of biological soil crusts from serpentine and non-serpentine soils at two precipitation levels. The bacterial and fungal communities were characterized using 16S rDNA and ITS metabarcoding, respectively. No significant differences could be found in bacterial richness and community structure. Nevertheless, bacterial taxa such as Archangium, Candidatus Solibacter, Chthoniobacter, and Microvirga were more abundant in serpentine biocrusts or biocrusts receiving lower precipitation. The fungal community structure was distinct between serpentine and non-serpentine soils (p = 0.027) and between high and low precipitation (p = 0.018). Furthermore, fungal diversity was lowest in the drier, serpentine biocrusts compared to non-serpentine (p = 0.001) and serpentine crusts receiving higher precipitation (p = 0.002). The fungal genera, Ramimonilia and Vishniacozyma, which are known to be resistant or tolerant to PTMs and other environmental extremes, were significantly more abundant (p = 0.036 and p = 0.016, respectively) in serpentine biocrusts, with the latter indicating serpentine habitats. This study concluded that soil type influenced the fungal alpha diversity, specifically in the serpentine soil, resulting in a decrease in fungal species richness. Furthermore, precipitation influenced fungal beta diversity by shaping distinct fungal communities found in the biocrusts of serpentine and non-serpentine soils.
Livestock grazing has been proposed as a cost-effective way to reclaim post-mining lands. It can enhance soil fertility and biodiversity, but its impacts on soil quality and microbial communities vary across soil types. Moreover, waste from grazing raises concerns about pathogens that could pose risks to animal and human health. This study investigated the effects of grazing on post-mining perlite-rich soil in central Thailand. A comparative analysis of soil physicochemical properties and bacterial diversity was conducted between grazed and ungrazed sites. Bacterial diversity was assessed using 16S amplicon sequencing. The perlite-rich soil was found to be sandy, acidic, and to have low nutritional content. Grazing significantly improved the soil texture and nutrient content, suggesting its potential as a cost-effective reclamation strategy. The 16S metagenomic sequencing analysis revealed that microbial communities were impacted by livestock grazing. Specifically, shifts in the dominant bacterial phyla were identified, with increases in Firmicutes and Chloroflexi and a decrease in Actinobacteria. Concerns about increased levels of pathogenic Enterobacteriaceae due to grazing were not substantiated in perlite-rich soil. These bacteria were consistently found at low levels in all soil samples, regardless of livestock grazing. This study also identified a diverse population of Streptomycetaceae, including previously uncharacterized strains/species. This finding could be valuable given that this bacterial family is known for producing antibiotics and other secondary metabolites. However, grazing adversely impacted the abundance and diversity of Streptomycetaceae in this specific soil type. In line with previous research, this study demonstrated that the response of soil microbial communities to grazing varies significantly depending on the soil type, with unique responses appearing to be associated with perlite-rich soil. This emphasizes the importance of soil-specific research in understanding how grazing affects microbial communities. Future research should focus on optimizing grazing practices for perlite-rich soil and characterizing the Streptomycetaceae community for potential antibiotic and secondary metabolite discovery. The obtained findings should ultimately contribute to sustainable post-mining reclamation through livestock grazing and the preservation of valuable microbial resources.
