In riverine water, both suspended particulate material and viruses are prominent ecological factors. The existence of various particle types and differences in viral abundance impose variability in microenvironments. Particulates and their microbial surrounding may interact in several ways, this interaction being strongly dependent on particle quality and the abundance of organisms involved. In laboratory experiments, we used different suspended matter types (fresh and aged mineral sediment and leaf litter, river snow) that typically occur in riverine environments as model particles. We investigated the effects of particle quality and different ambient viral abundances (×1, ×2 enrichments, and inactivated viruses) on several microbial parameters (changes in bacterial and viral abundances, bacterial production, specific bacterial production) of both the free-living and particle-attached fractions using water from a floodplain system of the Danube River (Austria). Both seston quality and variable viral abundances in the bulk water influenced some microbial parameters. The average abundance of bacteria and viruses was significantly higher on organic than on inorganic particles and on aged particles (for both sediment and leaf litter). Changes in bacterial abundance during the course of the experiments were also influenced by particle quality, with, for example, aged sediment favoring increasing abundances. Virus:bacterium ratios (VBR) were significantly higher on organic than on inorganic particles, but significantly lower on suspended particles than in the plank-tonic fraction. Typically, bacterial secondary production (overall and cell-specific) was higher on particles than in bulk water. Bacterial productivity in the ambient water was negatively affected by the abundance of planktonic viruses but positively affected by that of attached viruses. These findings from experimental systems may foster in situ studies of particle-rich environments.

中文翻译：

---

悬浮物质量和病毒丰度对微生物参数的影响：来自欧洲大河的实验证据

在河流水中，悬浮颗粒物质和病毒都是突出的生态因素。各种颗粒类型的存在和病毒丰度的差异在微环境中施加了可变性。颗粒物及其周围的微生物可能以多种方式相互作用，这种相互作用在很大程度上取决于颗粒质量和所涉及的生物体的丰度。在实验室实验中，我们使用了在河流环境中通常出现的不同悬浮物质类型（新鲜和老化的矿物沉积物和落叶、河雪）作为模型粒子。我们研究了颗粒质量和不同环境病毒丰度（×1、×2 富集和灭活病毒）对几个微生物参数（细菌和病毒丰度的变化、细菌产量、使用来自多瑙河（奥地利）洪泛区系统的水对自由生活和附着颗粒的部分进行特定的细菌生产）。散装水中的 seston 质量和可变的病毒丰度都会影响一些微生物参数。有机颗粒和老化颗粒（沉积物和落叶）上的细菌和病毒平均丰度显着高于无机颗粒。实验过程中细菌丰度的变化也受到颗粒质量的影响，例如，老化的沉积物有利于增加丰度。病毒：细菌比率（VBR）在有机颗粒上显着高于无机颗粒，但在悬浮颗粒上显着低于浮游生物部分。通常，颗粒上的细菌二次生产（整体和细胞特异性）高于散装水中。环境水中的细菌生产力受到浮游病毒丰度的负面影响，但受到附着病毒的积极影响。这些来自实验系统的发现可能会促进对富含粒子的环境进行原位研究。