Bacterial communities in the sediment of the Yangtze River influenced by rapid urbanization have thus far been under-investigated despite the importance of microorganisms as mass transporters. Here, the response patterns of the bacterial community along the Yangtze River to different levels of urbanization were generated using 16S rRNA Miseq sequencing. The results reveal that economic aspects have made the largest contribution (41.8%) to the urbanization along the Yangtze River. A clear declining tendency in the abundance of Chloroflexi and Acidobacteria and a significant increase in the abundance of Bacteroidetes were observed with an elevated urbanization level gradient. Bacterial diversity showed a negative relevance (P < 0.01) to the demographic, economic and social urbanization index. Per capita gross domestic product (GDP) (PCGDP) and the GDP of tertiary industry (GDP3) exhibited significantly (P < 0.05) negative correlations with the bacterial diversity, while a positive relationship between the pH and α-diversity (P < 0.05) was observed. Redundancy analysis revealed that PCGDP was significantly correlated (13.9%, P < 0.01) with the overall bacterial compositions, followed by temperature (10.8%, P < 0.01) and GDP3 (8.4%, P < 0.05). Meanwhile, the GDP3 (35.9%), the ratio of total nitrogen and total phosphorus (N/P) (12.9%) and the PCGDP (8.8%) were revealed to be most significantly related to the metabolic bacteria (P < 0.05). The metabolic functions of the bacteria related to the N-cycle and S-cycle were significant in the sediment of the Yangtze River. The variations of the bacterial community and metabolic function responding to the rapid urbanization were related to the economic development via the influence of the ‘mass effect’. In brief, the tertiary industry was significantly correlated with the variations in the composition of the metabolic community and the variations in the overall bacteria were both related to the tertiary and secondary industry.

中文翻译：

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细菌群落如何响应长江沿岸的城市化水平？

尽管微生物作为大众运输工具的重要性，但由于快速城市化的影响，长江沉积物中的细菌群落尚未得到充分研究。在这里，使用16S rRNA Miseq测序生成了长江沿岸细菌群落对不同城市化水平的响应模式。结果表明，经济因素对长江沿岸城市化贡献最大（41.8％）。在丰度的明显下降的趋势绿弯菌门和酸杆菌门和在丰度的增加显著拟杆菌与升高城市化水平梯度观察。细菌多样性呈负相关性（P<0.01）。人均国内生产总值（PCGDP）和第三产业GDP（GDP3）与细菌多样性呈显着负相关（P <0.05），而pH与α多样性呈正相关（P <0.05）被观测到。冗余分析显示PCGDP与总体细菌组成显着相关（13.9％，P <0.01），其次是温度（10.8％，P <0.01）和GDP3（8.4％，P <0.05）。同时，GDP3（35.9％），总氮和总磷比率（N / P）（12.9％）和PCGDP（8.8％）被发现与代谢细菌最相关（P <0.05）。与细菌的代谢功能有关的N循环和S循环在长江沉积物中具有重要意义。通过“质量效应”的影响，响应快速城市化的细菌群落和代谢功能的变化与经济发展有关。简而言之，第三产业与代谢群落组成的变化显着相关，总细菌的变化均与第三产业和第二产业有关。