Department of Biological Sciences, University of Namibia, Windhoek, Namibia.
Department of Environmental Sciences, UNISA Florida Campus, Johannesburg, RSA, South Africa.
Arch Microbiol. 2021 May;203(4):1753-1766. doi: 10.1007/s00203-020-02165-7. Epub 2021 Jan 20.
Coastal sands are important natural recreational facilities that have become hotspots for tourism and economic development. However, these sands harbour diverse microbial assemblages that play a critical role in the balance between public health and ecology. In this study, targeted high-throughput sequencing analysis was used to identify sand-borne bacterial populations at four public beaches in Durban. The effect of heavy metal in shaping the distribution of bacterial metacommunities was determined using canonical correspondence analysis (CCA), while the functional gene profiles were predicted using PICRUSt2 analysis. Sequences matching those of the bacterial phylum Proteobacteria were the most abundant in all samples, followed by those of the phyla Firmicutes, Actinobacteria, Bacteroidetes, and Gemmatimonadetes. Genus-level taxonomic analysis showed the presence of 1163 bacterial genera in all samples combined. The distribution of bacterial communities was shaped by heavy metal concentrations, with the distribution of Flavobacteria, Bacteroidia, and Deltaproteobacteria influenced by Pb and Zn, while B and Cr influenced the distribution of Clostridia and Gammaproteobacteria, respectively. Identified antibiotic resistance genes included the peptidoglycan biosynthesis gene II, III, IV, and V, as well as the polymyxin resistance gene, while the virulence genes included the sitA, fimB, aerobactin synthase, and pilL gene. Our findings demonstrate that beach sand-borne bacteria are reservoirs of virulence and antibiotic resistance genes. Contamination of beach sands with heavy metals selects for both heavy metal resistance and antibiotic resistance in beach sand bacterial communities. Children and immunocompromised people engaging in recreational activities on beaches may be exposed to higher risk of infection.
沿海沙滩是重要的自然休闲设施，已成为旅游和经济发展的热点。然而，这些沙滩蕴藏着多种微生物群落，它们在公共卫生和生态平衡中起着至关重要的作用。在这项研究中，我们使用靶向高通量测序分析方法，在德班的四个公共海滩上确定了沙滩携带的细菌种群。使用典范对应分析（CCA）确定重金属对细菌元群落分布的影响，同时使用 PICRUSt2 分析预测功能基因谱。在所有样本中，与细菌门变形菌门匹配的序列最为丰富，其次是厚壁菌门、放线菌门、拟杆菌门和芽单胞菌门。属水平的分类分析表明，所有样本中共存在 1163 个细菌属。细菌群落的分布受重金属浓度的影响，黄杆菌、拟杆菌和δ变形菌的分布受 Pb 和 Zn 影响，而 B 和 Cr 分别影响梭菌和γ变形菌的分布。鉴定出的抗生素抗性基因包括肽聚糖生物合成基因 II、III、IV 和 V 以及多粘菌素抗性基因，而毒力基因包括 sitA、fimB、aerobactin 合成酶和 pilL 基因。我们的研究结果表明，沙滩携带的细菌是毒力和抗生素抗性基因的储存库。沙滩沙中重金属的污染会选择沙滩沙细菌群落的重金属抗性和抗生素抗性。在沙滩上进行娱乐活动的儿童和免疫功能低下的人群可能面临更高的感染风险。
