Bacillus amyloliquefaciens is a ubiquitous soil and plant-associated bacterial species which shows structural and adaptative responses to the environment. This present paper explores the ability of the strain L-17 to form subaerial biofilms on a liquid surface. Hydrophobic and non-wetting properties were observed for the rough top biofilm layer in contact with the air, which are quite different to the hydrophilic properties which were observed for the smooth biofilm layer in contact with the liquid. Both pellicle interfaces were visualized by scanning electron microscopy revealing a complex three-dimensional architecture composed of exopolymers organized in stacked fibrous network or sheet-like structures in the vicinity of the subaerial surface. Disruption of the extracellular matrix by combining physical and chemical treatments indicated that both loosely and tightly bound polysaccharides were found as major components of this complex pellicle. Proteins were also involved in the aggregation and cohesion of the matrix as multi extraction steps were needed to recover some tightly bounded proteins. This was confirmed by applying protease treatment which was able to significantly disrupt the pellicle. Overall results underline the ability of B. amyloliquefaciens L-17 to survive on air-liquid interfaces. This feature offers an interesting strategy to escape aquatic environments and develop aerial biofilm in response to environmental changes involving wet–dry cycles.

解淀粉芽孢杆菌是一种无处不在的土壤和植物相关细菌物种，对环境表现出结构性和适应性反应。本论文探讨了菌株 L-17 在液体表面形成地下生物膜的能力。观察到与空气接触的粗糙顶部生物膜层的疏水性和非润湿性，这与观察到的与液体接触的光滑生物膜层的亲水性完全不同。通过扫描电子显微镜观察两个薄膜界面，揭示了复杂的三维结构，该结构由在地下表面附近的堆叠纤维网络或片状结构中组织的外聚合物组成。通过结合物理和化学处理破坏细胞外基质表明松散和紧密结合的多糖被发现是这种复杂薄膜的主要成分。蛋白质也参与基质的聚集和内聚，因为需要多次提取步骤来回收一些紧密结合的蛋白质。这通过应用能够显着破坏薄膜的蛋白酶处理得到证实。总体结果强调了B. amyloliquefaciens L-17 在气液界面上存活。此功能提供了一种有趣的策略，可以逃离水生环境并形成空气生物膜，以响应涉及干湿循环的环境变化。