scholarly journals Bacterial Community Characteristics and Enzyme Activities in Bothriochloa ischaemum Litter Over Progressive Phytoremediation Years in a Copper Tailings Dam

2020 ◽  
Vol 11 ◽  
Author(s):  
Tong Jia ◽  
Yuwen Wang ◽  
Baofeng Chai

Litter decomposition is the key link between material circulation and energy flow in ecosystems, resulting from the activity of resident microbes and various enzymes. This study investigated enzyme activity in litter and associated microbial community characteristics to help clarify the internal mechanisms associated with litter decomposition, while also providing researchers a scientific basis for soil remediation in mining areas. Results confirmed that the nutrient content of Bothriochloa ischaemum litter significantly increased as phytoremediation years progressed, while enzyme activities in litter varied over different phytoremediation years. During the litter decomposition process, cellulase predominated in the early phytoremediation stage and catalase predominated in the intermediate phytoremediation stage. Obvious differences were found in bacterial community structure and diversity over progressive phytoremediation years. Predominant bacterial genera mainly included Massilia, Sphingomonas, Curtobacterium, Amnibacterium, and Methylobacterium. Moreover, Methylorosula and Jatrophihabitans had relatively higher betweenness centrality, and played important roles in bacterial community positive interactions. Additionally, total nitrogen (TN) and total zinc in soil, sucrase and catalase activity in litter were the main environmental factors that affected the structural framework of bacteria in B. ischaemum litter. However, TN had the greatest overall effect on the structural framework of bacteria in litter. Results from this study can help our understanding of the role that litter plays in degraded ecosystems. Our results also provide a scientific basis for improving poor quality soil in areas affected by copper tailings while also amending ecological restoration efficiency.

Author(s):  
Tong Jia ◽  
Xiaoxia Liang ◽  
Tingyan Guo ◽  
Baofeng Chai

Litter decomposition is a critical component of the ecological nutritional transformation process. It is particularly important to investigate characteristics and interactions of bacterial communities in litter decomposition in heavy metal polluted degrade areas, which will help clarify driving mechanisms of organic matter and nutrient cycling in mining areas that harbor contaminated soil. Imperata cylindrical was the dominant plant species in the degrade area investigated; thus, we selected this species as research object. Here we explore bacterial community characteristics and key microbial groups as well as driving factors of litter decomposition using in-situ litter decomposition experiments. The nutrient content of I. cylindrica decreased, while the litter pH status increased as decomposition progressed in one of the three sub-dams investigated (i.e., S516). Proteobacteria and Actinobacteriota were the dominant bacterial phyla during the different litter decomposition stages. Moreover, the role of Friedmanniella was critical in sustaining both structure and function of the bacterial community during the early decomposition stage. Quadrisphaera became the dominant species as litter decomposition progressed. Litter properties and enzyme activities both had significant effects on litter bacterial community characteristics, whose driving factors varied during different restoration stages. The bacterial community dynamics of litter were affected primarily by litter properties during the decomposition process. Furthermore, the most crucial factors that impacted bacterial litter structure were pH and copper content. Findings will help to deepen our understanding of litter decomposition mechanisms in degraded ecosystems, while also providing a scientific basis for improving effectiveness of material circulation and nutrient transformation in degrade ecosystems.


2012 ◽  
Vol 518-523 ◽  
pp. 39-43
Author(s):  
Xiao Guang Zhao ◽  
Yuan Yuan Guan ◽  
Wen Yu Huang

In this paper, simulated experiments were performed in pots by using soil materials in different conditions of film remnant. Based on the research on soil microorganism quantity trends of soil enzyme activities were analyzed systematically: soil without film remnant, soil with film remnant for 5, 10, 15 and 20 years. By analyzing crop progress, the relationship with soil material was studied, in order to provide scientific basis for the variation laws between different conditions of film remnant and the activity of soil enzyme.


2022 ◽  
Vol 12 ◽  
Author(s):  
Yang Li ◽  
Wenjing Li ◽  
Lei Ji ◽  
Fanyong Song ◽  
Tianyuan Li ◽  
...  

The biodegradation of organic pollutants is the main pathway for the natural dissipation and anthropogenic remediation of polycyclic aromatic hydrocarbons (PAHs) in the environment. However, in the saline soils, the PAH biodegradation could be influenced by soil salts through altering the structures of microbial communities and physiological metabolism of degradation bacteria. In the worldwide, soils from oilfields are commonly threated by both soil salinity and PAH contamination, while the influence mechanism of soil salinity on PAH biodegradation were still unclear, especially the shifts of degradation genes and soil enzyme activities. In order to explain the responses of soils and bacterial communities, analysis was conducted including soil properties, structures of bacterial community, PAH degradation genes and soil enzyme activities during a biodegradation process of PAHs in oilfield soils. The results showed that, though low soil salinity (1% NaCl, w/w) could slightly increase PAH degradation rate, the biodegradation in high salt condition (3% NaCl, w/w) were restrained significantly. The higher the soil salinity, the lower the bacterial community diversity, copy number of degradation gene and soil enzyme activity, which could be the reason for reductions of degradation rates in saline soils. Analysis of bacterial community structure showed that, the additions of NaCl increase the abundance of salt-tolerant and halophilic genera, especially in high salt treatments where the halophilic genera dominant, such as Acinetobacter and Halomonas. Picrust2 and redundancy analysis (RDA) both revealed suppression of PAH degradation genes by soil salts, which meant the decrease of degradation microbes and should be the primary cause of reduction of PAH removal. The soil enzyme activities could be indicators for microorganisms when they are facing adverse environmental conditions.


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