Sediment Ecology Research Group, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland, United Kingdom.
PLoS One. 2010 Nov 2;5(11):e13794. doi: 10.1371/journal.pone.0013794.
It is recognized that microorganisms inhabiting natural sediments significantly mediate the erosive response of the bed ("ecosystem engineers") through the secretion of naturally adhesive organic material (EPS: extracellular polymeric substances). However, little is known about the individual engineering capability of the main biofilm components (heterotrophic bacteria and autotrophic microalgae) in terms of their individual contribution to the EPS pool and their relative functional contribution to substratum stabilisation. This paper investigates the engineering effects on a non-cohesive test bed as the surface was colonised by natural benthic assemblages (prokaryotic, eukaryotic and mixed cultures) of bacteria and microalgae. MagPI (Magnetic Particle Induction) and CSM (Cohesive Strength Meter) respectively determined the adhesive capacity and the cohesive strength of the culture surface. Stabilisation was significantly higher for the bacterial assemblages (up to a factor of 2) than for axenic microalgal assemblages. The EPS concentration and the EPS composition (carbohydrates and proteins) were both important in determining stabilisation. The peak of engineering effect was significantly greater in the mixed assemblage as compared to the bacterial (x 1.2) and axenic diatom (x 1.7) cultures. The possibility of synergistic effects between the bacterial and algal cultures in terms of stability was examined and rejected although the concentration of EPS did show a synergistic elevation in mixed culture. The rapid development and overall stabilisation potential of the various assemblages was impressive (x 7.5 and ×9.5, for MagPI and CSM, respectively, as compared to controls). We confirmed the important role of heterotrophic bacteria in "biostabilisation" and highlighted the interactions between autotrophic and heterotrophic biofilm consortia. This information contributes to the conceptual understanding of the microbial sediment engineering that represents an important ecosystem function and service in aquatic habitats.
据认识，栖息在自然沉积物中的微生物通过分泌天然粘性有机物质（EPS：细胞外聚合物），显著调节床层的侵蚀响应（“生态系统工程师”）。然而，对于主要生物膜成分（异养细菌和自养微藻）在其对 EPS 池的单独贡献及其对基质稳定化的相对功能贡献方面的个体工程能力，知之甚少。本文研究了自然底栖生物群落（细菌、真核生物和混合培养物的原核生物和真核生物）在非粘性测试床表面定殖时，对非粘性测试床的工程影响。MagPI（磁性粒子感应）和 CSM（粘性强度计）分别确定了培养表面的粘合能力和粘性强度。细菌组合的稳定化作用（高达 2 倍）明显高于无菌微藻组合。EPS 浓度和 EPS 组成（碳水化合物和蛋白质）对于确定稳定性都很重要。与细菌（x1.2）和无菌硅藻（x1.7）培养物相比，混合组合的工程效应峰值明显更高。尽管混合培养物中 EPS 的浓度确实显示出协同升高，但在细菌和藻类培养物之间稳定性的协同效应的可能性被排除了。各种组合的快速发展和整体稳定化潜力令人印象深刻（与对照相比，MagPI 和 CSM 分别为 x7.5 和 x9.5）。我们证实了异养细菌在“生物稳定化”中的重要作用，并强调了自养和异养生物膜共生体之间的相互作用。这些信息有助于理解微生物沉积物工程，这是水生栖息地中重要的生态系统功能和服务。
