School of Civil and Environmental Engineering, Georgia Institute of Technology, Ford Environmental Science & Technology Building, Atlanta, GA, 30332, USA.
Department of Civil Engineering, Indian Institute of Technology, Kanpur, UP, 208016, India.
Environ Microbiol. 2019 Jan;21(1):182-196. doi: 10.1111/1462-2920.14439. Epub 2018 Nov 15.
Little is known about microbial communities in the Ganges River, India and how they respond to intensive anthropogenic inputs. Here we applied shotgun metagenomics sequencing to study microbial community dynamics and function in planktonic samples collected along an approximately 700 km river transect, including urban cities and rural settings in upstream waters, before and after the monsoon rainy season. Our results showed that 11%-32% of the microbes represented terrestrial, sewage and human inputs (allochthonous). Sewage inputs significantly contributed to the higher abundance, by 13-fold of human gut microbiome (HG) associated sequences and 2-fold of antibiotic resistance genes (ARGs) in the Ganges relative to other riverine ecosystems in Europe, North and South America. Metagenome-assembled genome sequences (MAGs) representing allochthonous populations were detectable and tractable across the river after 1-2 days of (downstream) transport (> 200 km apart). Only approximately 8% of these MAGs were abundant in U.S. freshwater ecosystems, revealing distinct biodiversity for the Ganges. Microbial communities in the rainy season exhibited increased alpha-diversity and spatial heterogeneity and showed significantly weaker distance-decay patterns compared with the dry season. These results advance our understanding of the Ganges microbial communities and how they respond to anthropogenic pollution.
关于印度恒河中的微生物群落及其如何应对密集的人为输入，目前我们知之甚少。在这里，我们应用鸟枪法宏基因组测序来研究浮游生物样本中的微生物群落动态和功能，这些样本沿约 700 公里的河流横剖面采集，包括上游的城市和农村地区，以及季风雨季前后。我们的结果表明，11%-32%的微生物代表了陆地、污水和人类输入（异源）。与欧洲、北美和南美的其他河流生态系统相比，污水输入显著增加了恒河微生物群落（HG）相关序列的丰度，达到 13 倍，抗生素抗性基因（ARGs）的丰度达到 2 倍。在（下游）运输 1-2 天后（相距> 200 公里），可以检测到并追踪到代表异源种群的宏基因组组装基因组序列（MAGs）。这些 MAGs 中只有约 8%在北美淡水生态系统中丰度较高，这表明恒河具有独特的生物多样性。与旱季相比，雨季的微生物群落表现出更高的α多样性和空间异质性，且距离衰减模式明显较弱。这些结果增进了我们对恒河微生物群落及其对人为污染的响应的理解。
