包头市半干旱型森林公园土壤细菌多样性与功能

Soil bacterial diversity and function in semi-arid forest parks in Baotou City

土壤微生物是城市公园生态系统中物质循环的主要驱动者,但目前对于半干旱型城市公园森林土壤细菌群落结构和功能研究较少。本研究以包头市为例,选取奥林匹克公园(AL)、劳动公园(LD)和阿尔丁植物园(ZW) 3个典型的森林公园,利用Illumina高通量测序的方法对细菌16S rRNA V4-V5片段进行测序,分析城市森林公园土壤细菌的多样性、群落构成以及背后的生态学构建机制,并使用Tax4Fun对细菌群落代谢功能进行分析。结果表明,土壤细菌丰富度指数为LD (2,443.00±9.37)> ZW (2,392.90±8.23)> AL (2,305.57±17.48);细菌群落以放线菌门、变形菌门、酸杆菌门、绿弯菌门和芽单胞菌门为优势门。细菌群落组成在三个公园间存在显著差异,同时线性判别分析效应大小(LEfSe)结果表明,所有公园都具有多度显著差异的细菌可操作分类单元(OTUs);中性群落模型(NCM)、标准化随机率(NST)和基于系统发育结合的零模型推断群落组装机制(i CAMP)分析显示,城市森林土壤细菌群落的构建是由随机性过程和确定性过程共同驱动,其中漂变和同质化选择占主导作用。Tax4Fun功能预测结果表明涉及膜运输、碳水化合物代谢、氨基酸代谢、能量代谢和信号转导的代谢是该城市公园林下土壤微生物的主要代谢功能,进一步分析表明微生物群落的代谢功能在不同公园之间存在很大差异。本研究初步探究了半干旱型城市公园细菌的多样性、群落构建机制及其功能,为城市公园绿地建设以及生态改善等提供一定的科学依据和实践指导。

Aim: Soil microorganisms are the main drivers of material cycling in urban park ecosystems, but there are few studies on the structure and function of forest soil bacterial communities in semi-arid urban parks.Methods: In this study, three typical forest parks, Olympic Park(AL), Laodong Park(LD) and Aerding Botanical Garden(ZW) in Baotou City were selected, and the bacterial 16S rRNA V4-V5 regions were sequenced using Illumina high-throughput sequencing techniques to analyze the diversity, community composition and the mechanism underlying community assembly of bacteria. The metabolic functions of the bacterial community were also analyzed using Tax4Fun.Results: The results showed that soil bacterial richness index were LD(2,443.00 ± 9.37) > ZW(2,392.90 ± 8.23) > AL(2,305.57 ± 17.48). Actinobacteriota, Proteobacteria, Acidobacteriota, Chloroflexi, and Gemmatimonadota were the dominant phyla. Bacterial community composition differed significantly among the three parks, and linear discriminant analysis effect size(LEfSe) results indicated that all parks harbored significant opertational taxonomic units in abundance. The neutral community model(NCM), normalized stochasticity ratio(NST), and the infer community assembly mechanisms by phylogenetic-bin-based null model analysis(iCAMP) showed that community assembly of bacteria in urban forests was determined by the combination of stochastic and deterministic processes, with drift and homogeneous selection being the dominant ecological processes. The results of Tax4Fun functional prediction indicated that metabolism involving membrane transport, carbohydrate metabolism, amino acid metabolism, energy metabolism and signal transduction were the main metabolic functions of soil bacteria in these urban parks, and further analysis showed that the metabolic functions of microbial communities differed across parks. Conclusion: Our study investigated preliminarily the diversities, community assembly mechanisms and functions of bacteria in the semi-arid urban parks, which could provide basic data and scientific basis for urban park green space construction and ecological improvement.