Cells in biofilms dynamically adapt to surrounding environmental conditions, which alters biofilm architecture. The obligate anaerobic pathogen Clostridium perfringens shows different biofilm structures in different temperatures. Here we find that the temperature-regulated production of extracellular polymeric substance (EPS) is necessary for morphological changes in biofilms. We identify BsaA proteins as an EPS matrix necessary for pellicle biofilm formation at lower temperature and find that extracellularly secreted BsaA protein forms filamentous polymers. We show that sipW-bsaA operon expression is bimodal, and the EPS-producing population size is increased at a lower temperature. This heterogeneous expression of the EPS gene requires a two-component system. We find that EPS-producing cells cover EPS-nonproducing cells attaching to the bottom surface. In the deletion mutant of pilA2, encoding a type IV pilin, the EPS gene expression is ON in the whole population. This heterogeneity is further regulated by the cleavage of the pilA2 mRNA by RNase Y, causing temperature-responsive EPS expression in biofilms. As temperature is an environmental cue, C. perfringens may modulate EPS expression to induce morphological changes in biofilm structure as a strategy for adapting to interhost and external environments.

生物膜中的细胞可以动态适应周围的环境条件，从而改变生物膜的结构。专性厌氧性病原菌产气荚膜梭菌在不同温度下表现出不同的生物膜结构。在这里，我们发现温度调节的细胞外聚合物（EPS）的生产对于生物膜的形态变化是必要的。我们将BsaA蛋白鉴定为在较低温度下薄膜生物膜形成所必需的EPS基质，并发现细胞外分泌的BsaA蛋白形成丝状聚合物。我们显示sipW-bsaA操纵子表达是双峰的，并且在较低温度下产生EPS的种群规模增加。EPS基因的这种异质表达需要两组分系统。我们发现，EPS产生细胞覆盖附着在底面上的非EPS产生细胞。在编码IV型菌毛蛋白的pilA2缺失突变体中，EPS基因的表达在整个种群中都为ON。RNase Y对pilA2 mRNA的切割进一步调节了这种异质性，从而引起了生物膜中温度响应性EPS的表达。由于温度是环境的提示，产气荚膜梭菌可以调节EPS表达以诱导生物膜结构的形态变化，作为适应宿主内部和外部环境的策略。