Deciphering the Microbial Community Characteristics in Sediment Derived from a Rainwater Harvesting Cellar in Northwestern China

Rainwater harvested in cellars is widely used for domestic water supply in rural areas of Northwestern China to prevent water shortages. Microorganisms in rainwater harvesting cellar sediment (RHCS) are the driving force of elemental translocation and water purification in the rainwater cellar ecosystem. In this study, 16S-rRNA high-throughput gene sequencing and relevant analytical methods were used to explore the microbial community distribution, structure, function, and the influence of environmental factors of two different (cement and red clay) RHCS from peasant households in the arid and semi-arid regions of Northwestern China. Proteobacteria (γ-Proteobacteria) with Pseudomonadales (Pseudomonas) were the predominant microorganisms, playing an important role in the metabolism of amino acids, carbohydrates, lipids, cofactors and vitamins, nucleotides, and xenobiotics. Taxa with lower relative abundance were able to metabolize terpenoids, polyketides, glycans, and other amino acids, promoting biosynthesis of other secondary metabolites as well as glycans. In addition, enzyme families were identified. Most bacterial phyla were negatively correlated with nitrate nitrogen (NO3--N), total nitrogen (TN), and organic matter, while ammonia nitrogen (NH4+-N) and total phosphorus (TP) were positively correlated with corresponding dominant microbial genera. Nearly all taxa were negatively correlated with TN. Strong functional associations existed between most microorganisms. This study provides a basis for the understanding of microbial community structures and relationships, as well as their relationships with environmental factors in RHCS. To improve rainwater quality, non-point pollution management and control methods are necessary, such as keeping the rainwater harvesting surface clean, discarding initial rainwater runoff, and guiding the rainwater flow path.