Effect of Copper and Nickel on Soil Enzymatic Activities and Microbial Abundance and Diversity using Illumina MiSeq platforms

The objectives of this study were to determine the effects of nickel and copper on soil enzymatic activity and microbial communities in an environmentally controlled setting. Soil samples were treated with copper sulfate (1,300 mg kg-1) and nickel sulfate (1,600 mg kg-1). To determine the effect of Cu and Ni ions, potassium sulfate and water were used as controls and the treated soils were incubated for 100 days in a growth chamber. Nine enzymes were targeted including beta-glucosidase (BG), cellobiohydrolase (CBH), beta-N-acetylglucosaminidase (NAGase), aryl sulfatase (AS), acid phosphatase (AP), alkaline phosphatase (AlP), glycine aminopeptidase (GAP), leucine aminopeptidase (LAP), and peroxidase (PER). Surprisingly, only potassium sulfate used as a salt control induced a significant increase of the glycine-aminopeptidase (GAP) enzyme. The Illumina MiniSeq Platform was used to measure bacterial and fungal abundance and diversity. Candidatus Koribacter was the most abundant genus representing 27.6% of all bacterial genera followed by Chthoniobacter (7%), Granulicella (6.6%), and Acidobacterium (5.8%). For fungi, Russula and Tricholoma (13.4%) were the most prevalent genera followed by Hydnum (10.4%) and Cuphophyllus (8.8%). There was a significant reduction of relative abundance of the top five most abundant genera induced by copper ions compared to potassium sulfate and water. Copper also decreased significantly the levels of Amplicon Sequence Variants (ASV) and Shannon Diversity Index values for both bacteria and fungi. The effects of Ni on these indices were not significant compared to controls. Beta diversity analysis revealed no clear grouping or clustering based on treatments for both bacteria and fungi

本研究旨在探明镍与铜在环境可控条件下对土壤酶活性及微生物群落的影响。实验将土壤样品分别以硫酸铜（1300 mg·kg⁻¹）与硫酸镍（1600 mg·kg⁻¹）进行处理。为明确铜、镍离子的效应，以硫酸钾与水作为对照，处理后的土壤于生长箱中孵育100天。本次实验靶向9种土壤酶，包括β-葡萄糖苷酶（beta-glucosidase, BG）、纤维二糖水解酶（cellobiohydrolase, CBH）、β-N-乙酰氨基葡萄糖苷酶（beta-N-acetylglucosaminidase, NAGase）、芳基硫酸酯酶（aryl sulfatase, AS）、酸性磷酸酶（acid phosphatase, AP）、碱性磷酸酶（alkaline phosphatase, AlP）、甘氨酸氨基肽酶（glycine aminopeptidase, GAP）、亮氨酸氨基肽酶（leucine aminopeptidase, LAP）以及过氧化物酶（peroxidase, PER）。出乎意料的是，仅作为盐对照的硫酸钾处理组，其甘氨酸氨基肽酶（GAP）的活性出现显著升高。采用Illumina MiniSeq测序平台（Illumina MiniSeq Platform）测定细菌与真菌的丰度及多样性。细菌群落中，Candidatus Koribacter为最优势菌属，占所有细菌属的27.6%，其次依次为Chthoniobacter（7%）、Granulicella（6.6%）与Acidobacterium（5.8%）。真菌群落中，Russula与Tricholoma合计占比13.4%，为最优势菌属，其后依次为Hydnum（10.4%）与Cuphophyllus（8.8%）。相较于硫酸钾与水对照组，铜离子处理显著降低了前五大优势菌属的相对丰度。此外，铜离子还显著降低了细菌与真菌的扩增子序列变异体（Amplicon Sequence Variants, ASV）数量以及香农多样性指数（Shannon Diversity Index）值。镍离子对上述两类指标的影响与对照组相比无显著性差异。β多样性分析结果显示，无论细菌还是真菌群落，各处理组均未形成明确的分组或聚类。