Biofilms and type III secretion are not mutually exclusive in Pseudomonas aeruginosa

Biofilm formation and type III secretion have been shown to be reciprocally regulated in P. aeruginosa, and it has been suggested that factors related to acute infection may be incompatible with biofilm formation. We investigated how growth conditions influence the production of virulence factors by studying the inter-relationships between colonies, biofilms and planktonic cells. We found that biofilms in our growth conditions express the type III secretion and these lifestyles are therefore not mutually exclusive in P. aeruginosa. Keywords: Comparison of different growth modes and growth phases of Pseudomonas aeruginosa Pseudomonas aeruginosa cells grown in five different conditions were analysed with three biological replicates for each sample. The five different conditions were planktonic cells in exponential phase, planktonic cells in stationary phase, colonies on agar plates incubated for 15 or 40 hours and biofilms in a continuous flow system after three days of growth.

已有研究证实，铜绿假单胞菌（Pseudomonas aeruginosa，简称P. aeruginosa）的生物被膜形成（biofilm formation）与三型分泌系统（type III secretion）存在相互调控关系，且有研究提出与急性感染相关的毒力因子可能与生物被膜形成相互排斥。
本研究通过探究菌落、生物被膜与浮游态细胞（planktonic cells）之间的相互关联，解析了生长条件对毒力因子产生的调控作用。
研究发现，在本研究设定的生长条件下，生物被膜会表达三型分泌系统相关因子，因此铜绿假单胞菌的这两种生存模式并非互斥。
关键词：铜绿假单胞菌不同生长模式与生长阶段的比较
本研究对五种不同生长条件下的铜绿假单胞菌细胞进行了分析，每个样本设置三次生物学重复（biological replicates）。五种生长条件分别为：指数期（exponential phase）浮游态细胞、稳定期（stationary phase）浮游态细胞、琼脂平板（agar plates）上培养15小时或40小时的菌落，以及连续流系统（continuous flow system）中生长三日形成的生物被膜。