Coaggregation, a phenomenon contributing to biofilm formation, occurs among biofilm bacteria from different aquatic environments. However, not much is known about molecules involved in aggregation. In this study, freshwater, estuarine and marine biofilm bacteria were evaluated for aggregation capabilities, and their cell-bound extracellular polymeric substances (CB-EPS), known to play an important role in biofilm formation, were characterized for functional groups, and sugar composition via Fourier-transform infrared spectroscopy and high-pressure liquid chromatography. Biofilm-forming potential of estuarine and freshwater biofilm bacteria was higher as indicated by their coaggregation scores, attributed to CB-EPS with distinct sugar types, compared to marine. Most of the biofilm bacteria lost their ability to coaggregate after removal of CB-EPS, indicating its importance in coaggregation. Estuarine (Bacillus indicus, Bacillus cereus), and freshwater (Exiguobacterium spp., B. cereus) bacterial pairs, retained their aggregation capability probably via expression of lipids and proteins, suggesting their ability to rebuild themselves by expressing specific biomolecules under stressed conditions. A similar expression pattern was observed when these strains were exposed to abrupt salinity change (environmental stressor), indicating modulation of cell surface chemistry as a strategy to protect biofilm bacteria in harsh conditions. Unravelling role of these biomolecules as cues for settlement of macrofoulers is a step ahead.

来自不同水生环境的生物膜细菌之间发生聚集现象，这是导致生物膜形成的一种现象。然而，关于聚集涉及的分子知之甚少。在这项研究中，评估了淡水，河口和海洋生物膜细菌的聚集能力，并对其功能性基团和糖成分进行了表征，这些细胞结合的细胞外聚合物质（CB-EPS）在生物膜形成中起着重要作用。通过傅立叶变换红外光谱和高压液相色谱。与海洋相比，河口和淡水生物膜细菌的生物膜形成潜力更高，这是由于它们的共聚集分数所致，这归因于具有不同糖类型的CB-EPS。去除CB-EPS后，大多数生物膜细菌丧失了聚集能力，说明其在聚合中的重要性。河口（蜓芽孢杆菌，蜡状芽孢杆菌），和淡水（微小杆菌属，蜡状芽孢杆菌）细菌对，保持了它们的聚集能力可能是通过脂质和蛋白质的表达，提示其通过强调的条件下表达特定的生物分子来重建他们自己的能力。当这些菌株暴露于盐度突变（环境胁迫）时，观察到相似的表达模式，表明调节细胞表面化学作为在恶劣条件下保护生物膜细菌的策略。揭开这些生物分子作为解决大型污垢的线索的作用是向前迈出了一步。