Effects of Heavy Metals/Metalloids and Soil Properties on Microbial Communities in Farmland in the Vicinity of a Metals Smelter

Abstract

Microorganisms play a fundamental role in biogeochemical cycling and are highly sensitive to environmental factors, including the physiochemical properties of the soils and the concentrations of heavy metals/metalloids. In this study, high-throughput sequencing of the 16S rRNA gene was used to study the microbial communities of farmland soils in farmland in the vicinity of a lead–zinc smelter. Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Gemmatimonadetes were the predominant phyla in the sites of interest. Sphingomonas, Gemmatimonas, Lysobacter, Flavisolibacter, and Chitinophaga were heavy metal-/metalloid-tolerant microbial groups with potential for bioremediation of the heavy metal/metalloid contaminated soils. However, the bacterial diversity was different for the different sites. The contents of heavy metal/metalloid species and the soil properties were studied to evaluate the effect on the soil bacterial communities. The Mantel test revealed that soil pH, total cadmium (T-Cd), and available arsenic played a vital role in determining the structure of the microbial communities. Further, we analyzed statistically the heavy metals/metalloids and the soil properties, and the results revealed that the microbial richness and diversity were regulated mainly by the soil properties, which correlated positively with organic matter and available nitrogen, while available phosphorus and available potassium were negatively correlated. The functional annotation of the prokaryotic taxa (FAPROTAX) method was used to predict the function of the microbial communities. Chemoheterotrophy and airborne chemoheterotrophy of the main microbial community functions were inhibited by soil pH and the heavy metals/metalloids, except in the case of available lead. Mantel tests revealed that T-Cd and available zinc were the dominant factors affecting the functions of the microbial communities. Overall, the research indicated that in contaminated soils, the presence of multiple heavy metals/metalloids, and the soil properties synergistically shaped the structure and function of the microbial communities.

Exploring the diversity and structural response of sediment-associated microbiota communities to environmental pollution at the siangshan wetland in Taiwan using environmental DNA metagenomic approach

“…Proteobacteria are reported in both HMs contaminated and uncontaminated regions (Ma et al, 2015;Yan et al, 2016). Previous studies documented the response of Proteobacteria to HMs contamination in polluted habitats (Hu et al, 2021;Liu et al, 2021b;Serrana and Watanabe, 2022). Bacteroidota (class Bacteroidia) and Cyanobacteria (class Cyanobacteria) were more abundant phyla in surface sediments of MA1.F with relative abundances of 23.91% and 26.40%, respectively.…”

Applying EDTA in Chelating Excess Metal Ions to Improve Downstream DNA Recovery from Mine Tailings for Long-Read Amplicon Sequencing of Acidophilic Fungi Communities

“…Metamorphic environments such as tailings are characterized by high metal concentrations and extremely low pH ranges. These factors contribute to the diversity structure of the acidophilic or acid-tolerant communities found in that environment [ 40 , 41 ]. As a result, the taxonomic abundance of the fungal community observed in the four tailing samples was influenced by their habitat.…”

The rhizosphere microbiome improves the adaptive capabilities of plants under high soil cadmium conditions

“…Moreover, these two genera were reported to exhibit the capacity to use a wide range of root exudates ( Krishnan et al, 2017 ) and mobile Ni from rhizosphere soils ( Chen J. et al, 2020 ). Gemmatimonas , the dominant species in rhizosphere soils of the AE of S. alfredii , were reportedly involved in metal mobilization by enhancing microbial nitrogen fixation ( Hu et al, 2021 ). Members of Cupriavidus and Nocardioides showed plant growth-promoting capacities via P and K solubilization and were also reportedly involved in metal resistance and mobilization in rhizosphere soils ( Abdulla, 2009 ).…”

“…Microbial nitrogen fixation converts atmospheric dinitrogen into ammonia, a type of biologically active nitrogen, to support the growth of both microbes and the host plant in nutrient-stressed environments ( Tao et al, 2019 ). Generally, microbial mediated nitrogen fixation can also secrete a variety of organic acids to mobilize metals ( Hu et al, 2021 ). In the current study, the fixK gene, which encodes a nitrogen fixation-regulating protein, was enriched in the AE rhizosphere soils, demonstrating that nitrogen-fixing genes are overrepresented in the AE of S. alfredii ( Figure 4 ).…”

“…The results showed that the fixK gene sequences were primarily from Gemmatimonas and Nocardioides at the genus level. Gemmatimonas and Nocardioides were widely identified in metal-impacted environments and tolerated elevated levels of Cd ( Abdulla, 2009 ; Hu et al, 2021 ). These facts indicate the potential that elevated Cd levels not only regulate the enrichment of microorganisms with microbial nitrogen fixation functions to alleviate soil N but also mobilize Cd from the rhizosphere soil, which is consistent with previous studies ( Chen Y. et al, 2020 ).…”