Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino (FI), Italy.
G.I.D.A. S.p.A., Via di Baciacavallo 36, 59100 Prato (PO), Italy.
FEMS Microbiol Ecol. 2018 Nov 1;94(12). doi: 10.1093/femsec/fiy181.
Epilithic river biofilms characterize the rock surfaces along the Acquarossa river (Viterbo, Italy); they are in part red and in part black colored, maintaining a well-defined borderline. This peculiarity has raised questions about the biotic and abiotic phenomena that might avoid the mixing of the two biofilms. In this study, the structuring of bacterial communities in black and red epilithic biofilm in the Acquarossa river has been investigated with both culture dependent and independent approaches. Data obtained highlighted a (very) different taxonomic composition of black and red epilithons bacterial communities, dominated by Acinetobacter sp. and iron-oxidizing bacteria, respectively. The chemical characterization of both river water and biofilms revealed a substantial heavy metals pollution of the environment; heavy metals were also differentially accumulated in red and black epilithons. Overall, our data revealed that the structuring of red and black epilithons might be affected mainly by the antagonistic interactions exhibited by bacterial genera dominating the two biofilms. These findings suggest that biotic factors might be responsible for the structuring of natural bacterial communities, suggesting that there is a selection of populations at very small scale, and that different populations might compete for different niches.
附生于河石表面的河川生物膜是 Acquarossa 河（意大利维泰博）的主要特征；它们一部分是红色，一部分是黑色，并且保持着清晰的分界线。这种独特性引发了人们对可能避免两种生物膜混合的生物和非生物现象的疑问。在这项研究中，我们采用了依赖培养和非依赖培养的方法，调查了 Acquarossa 河黑色和红色附生生物膜中细菌群落的结构。研究结果表明，黑色和红色附生生物膜的细菌群落的分类组成（非常）不同，分别由不动杆菌属和氧化铁细菌属主导。对河水和生物膜的化学特征分析表明，环境受到了大量重金属的污染；重金属在红色和黑色附生生物膜中也有不同程度的积累。总的来说，我们的数据表明，红色和黑色附生生物膜的结构可能主要受到主导两种生物膜的细菌属之间的拮抗相互作用的影响。这些发现表明，生物因素可能是自然细菌群落结构形成的原因，这表明在非常小的尺度上存在种群的选择，并且不同的种群可能会争夺不同的生态位。
