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Untangling assembly and microbial interaction of abundant and rare microbiota in aquatic ecosystem is pivotal for understanding how community assembly respond to environmental variables and co-occurrence patterns. Here, we explored the assembly mechanisms, their drivers, and species co-occurrence of abundant and rare microbiomes in the Yellow River using 16S rRNA gene sequencing in Lanzhou, China. Here, abundant community was ubiquitous across all sites, whereas rare community was uneven distributed. The richness and community dissimilarity of rare taxa were significantly greater than those of abundant ones. Stochastic processes structured the rare community assembly in spring and winter, while deterministic processes shaped the abundant and rare community assembly in other seasons and all sites. Copper and water temperature mediated the balance between deterministic and stochastic processes of abundant and rare community, respectively. A few abundant taxa with closer relationships frequently occupied central positions and had a great effect on other co-occurrences in the network, while the majority of keystone microbiota were rare microbiome and played a considerable part in maintaining the network structure. Our study provides some ecological proposals for water quality management and ecological stability of the Yellow River. Key points: • Deterministic process dominated abundant and rare community assembly. • Cu and TW mediated the balance of abundant and rare community assembly respectively. • Abundant taxa had a greater effect on other co-occurrences in the network. [ABSTRACT FROM AUTHOR]

Skin microbiomes function directly in human health and are affected by various external and internal factors. However, few studies have showed the variation of human skin microbiota at multiple body sites in individuals of different national origin living in the same environment. Here, using 16S rRNA sequencing, we investigated the diversity and function of skin microbiomes in different body locations of Chinese and Pakistani individuals from a single college in China. Body location and nationality significantly affected community structures, while season and gender only impacted community member. Due to different lifestyles and likely genetic characteristics of the hosts, Proteobacteria was more abundant in Pakistanis than in Chinese individuals. There were significant differences in the Shannon diversity of skin microorganisms among different skin sites of Chinese individuals, but not in Pakistanis. PICRUSt prediction indicated that gene functions involved in carbohydrate metabolism, lipid metabolism, and xenobiotics biodegradation and metabolism were higher in bacteria collected from Pakistanis than those from Chinese individuals, but the amino acid metabolism of skin microorganisms in Chinese people was higher. The relative abundances of potential pathogenic bacteria also differed in different body locations, providing a foundation for studying skin-associated bacterial diseases. Through a meta-analysis of 233 human skin samples from eight elevational sites in western China, we found that skin microbial diversity first decreased and then increased with increasing altitude. Network analysis showed positive correlation between altitude and Lactobacillus, Chryseobacterium, or Acinetobacter. Our results uncover the variation of human skin microbiota allowing future explorations of potential significance for human health. Key points: • Body location and nationality affect skin microbiota diversity and function. • Proteobacteria was more abundant in Pakistanis than in Chinese. • Skin microbial diversity first decreased and then increased with elevated altitude. [ABSTRACT FROM AUTHOR]