Department of Limnology and Bio-Oceanography, Center of Functional Ecology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
Research and Development Center for Marine Biosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natushima 2-15, Yokosuka, Kanagawa, 237-0061, Japan.
Microb Ecol. 2019 Jul;78(1):1-5. doi: 10.1007/s00248-018-1293-y. Epub 2018 Nov 17.
In the marine environment, the abundance of Bacteria and Archaea is either controlled bottom-up via nutrient availability or top-down via grazing. Heterotrophic nanoflagellates (HNF) are mainly responsible for prokaryotic grazing losses besides viral lysis. However, the grazing specificity of HNF on specific bacterial and archaeal taxa is under debate. Bacteria and Archaea might have different nutritive values and surface properties affecting the growth rates of HNF. In this study, we offered different bacterial and archaeal strains with different morphologic and physiologic characteristics to Cafeteria roenbergensis, one of the most abundant and ubiquitous species of HNF in the ocean. Two Nitrosopumilus maritimus-related strains isolated from the northern Adriatic Sea (Nitrosopumilus adriaticus, Nitrosopumilus piranensis), two Nitrosococcus strains, and two fast growing marine Bacteria (Pseudoalteromonas sp. and Marinobacter sp.) were fed to Cafeteria cultures. Cafeteria roenbergensis exhibited high growth rates when feeding on Pseudoalteromonas sp., Marinobacter sp., and Nitrosopumilus adriaticus, while the addition of the other strains resulted in minimal growth. Taken together, our data suggest that the differences in growth of Cafeteria roenbergensis associated to grazing on different thaumarchaeal and bacterial strains are likely due to the subtle metabolic, cell size, and physiological differences between different bacterial and thaumarchaeal taxa. Moreover, Nitrosopumilus adriaticus experienced a similar grazing pressure by Cafeteria roenbergensis as compared to the other strains, suggesting that other HNF may also prey on Archaea which might have important consequences on the global biogeochemical cycles.
在海洋环境中，细菌和古菌的丰度要么通过营养物质的可利用性进行自下而上的控制，要么通过摄食进行自上而下的控制。异养纳米鞭毛虫（HNF）除了病毒裂解外，主要负责原核生物的摄食损失。然而，HNF 对特定细菌和古菌类群的摄食特异性仍存在争议。细菌和古菌可能具有不同的营养价值和表面特性，影响 HNF 的生长速度。在这项研究中，我们向海洋中最丰富和最普遍的 HNF 之一——Cafeteria roenbergensis 提供了具有不同形态和生理特征的不同细菌和古菌菌株。从亚得里亚海北部分离出的两个与 Nitrosopumilus maritimus 相关的菌株（Nitrosopumilus adriaticus、Nitrosopumilus piranensis）、两个 Nitrosococcus 菌株和两个快速生长的海洋细菌（Pseudoalteromonas sp. 和 Marinobacter sp.）被喂食给 Cafeteria 培养物。当以 Pseudoalteromonas sp.、Marinobacter sp. 和 Nitrosopumilus adriaticus 为食时，Cafeteria roenbergensis 表现出很高的生长速率，而添加其他菌株则导致生长最小。总之，我们的数据表明，Cafeteria roenbergensis 与不同的古菌和细菌菌株摄食相关的生长差异可能是由于不同细菌和古菌类群之间微妙的代谢、细胞大小和生理差异所致。此外，与其他菌株相比，Nitrosopumilus adriaticus 经历了 Cafeteria roenbergensis 相似的摄食压力，这表明其他 HNF 也可能捕食古菌，这可能对全球生物地球化学循环产生重要影响。
