Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
Sci Total Environ. 2017 Dec 1;601-602:1775-1784. doi: 10.1016/j.scitotenv.2017.06.052.
Bacteria are abundant in atmospheric waters and can be disseminated by precipitation to the surface of the Earth, potentially influencing ecosystems, public health and climate. However, data on bacterial communities in rainwater, especially on the association with weather, are very limited. In this study, rainwater was collected at the coastal city Kumamoto, southwestern Japan, in 2015. The bacterial communities in fourteen samples were identified using 16S rRNA sequencing and compared according to the rain types at the synoptic scale, i.e., cyclones, Meiyu and non-Meiyu stationary fronts, and typhoons. Diverse bacterial communities were present in all four types of rainwater and were dominated by the phyla Proteobacteria (37%), Bacteroidetes (16%), Cyanobacteria (14%), Actinobacteria (9%), Acidobacteria (8%) and Firmicutes (5%). Approximately half of the phyla (16 out of 33) were common among the rain types. The operational taxonomic units (OTUs) common among the four types of rainwater represented the majority (averagely 74%) of the sequences, indicating the predominance of common bacterial OTUs regardless of rain type. On the other hand, the synoptic weather systems and the origins of air masses associated with the rain likely resulted in distinct bacterial communities. High fractions of bacterial soil indicator taxa signified the large contribution of bacteria from soils. Genera containing ice nucleation-active bacteria were identified in all samples except one typhoon rain sample. Marine bacterial taxa, e.g., Pseudoalteromonas, Synechococcus and Marinobacter, were detected in several samples, indicating the dispersal of marine bacteria via clouds and rainwater. Fecal indicator bacteria were also detected in all samples. Thus, the bacteria in the four types of rainwater were characterized by largely overlapping communities with some differences in community composition, indicating that rain is an efficient pathway for the dissemination of bacterial communities in nature and links continental, marine and island ecosystems.
细菌在大气水中大量存在，可通过降水传播到地球表面，从而对生态系统、公共健康和气候产生潜在影响。然而，有关雨水（尤其是与天气有关的雨水）中细菌群落的数据非常有限。本研究于 2015 年在日本西南部熊本市沿海地区采集雨水。通过 16S rRNA 测序对 14 个样本中的细菌群落进行了鉴定，并根据天气系统（即气旋、梅雨锋和非梅雨锋以及台风）对它们进行了比较。四种类型的雨水中均存在多样的细菌群落，其优势菌门为变形菌门（37%）、拟杆菌门（16%）、蓝细菌（14%）、放线菌门（9%）、酸杆菌门（8%）和厚壁菌门（5%）。约一半的菌门（33 个中的 16 个）在四种雨水中都有出现。四种雨水中共同存在的操作分类单元（OTUs）代表了大部分序列（平均占 74%），表明无论雨型如何，常见细菌 OTUs 都占主导地位。另一方面，天气系统和与降雨相关的气团来源可能导致了不同的细菌群落。细菌土壤指示分类群的高分数表明，来自土壤的细菌贡献很大。除了一个台风雨样本外，所有样本中都鉴定出含有冰核活性细菌的属。在几个样本中检测到海洋细菌分类群，如假交替单胞菌、聚球藻和海杆菌，表明海洋细菌通过云和雨水传播。所有样本中均检测到粪便指示菌。因此，四种类型雨水中的细菌具有很大程度上重叠的群落，群落组成存在一些差异，这表明雨水是细菌群落在自然界中传播的有效途径，将大陆、海洋和岛屿生态系统联系起来。
