We previously showed the isolation of biofilm‐persistent Pseudomonas putida mutants that fail to undergo biofilm dispersal upon entry in stationary phase. Two such mutants were found to bear insertions in PP0914, encoding a GGDEF/EAL domain protein with high similarity to Pseudomonas aeruginosa BifA. Here we show the phenotypic characterization of a ΔbifA mutant in P. putida KT2442. This mutant displayed increased biofilm and pellicle formation, cell aggregation in liquid medium and decreased starvation‐induced biofilm dispersal relative to the wild type. Unlike its P. aeruginosa counterpart, P. putida BifA did not affect swarming motility. The hyperadherent phenotype of the ΔbifA mutant correlates with a general increase in cyclic diguanylate (c‐di‐GMP) levels, Congo Red‐binding exopolysaccharide production and transcription of the adhesin‐encoding lapA gene. Integrity of the EAL motif and a modified GGDEF motif (altered to GGDQF) were crucial for BifA activity, and c‐di‐GMP depletion by overexpression of a heterologous c‐di‐GMP phosphodiesterase in the ΔbifA mutant restored wild‐type biofilm dispersal and lapA expression. Our results indicate that BifA is a phosphodiesterase involved in the regulation of the c‐di‐GMP pool and required for the generation of the low c‐di‐GMP signal that triggers starvation‐induced biofilm dispersal.

中文翻译：

---

c-di-GMP磷酸二酯酶BifA调节恶臭假单胞菌中生物膜的发育。

我们以前表明生物膜持久的隔离P假单胞菌恶臭未能在静止期进入经过生物膜分散的突变体。两个这样的突变体被发现熊插入在PP0914，编码具有高相似性的GGDEF / EAL域蛋白P假单胞菌铜绿假单胞菌 BIFA。在这里，我们显示了P中ΔbifA突变体的表型特征。putida  KT2442。相对于野生型，该突变体显示出增加的生物膜和防护膜形成，液体培养基中的细胞聚集，并且减少了饥饿诱导的生物膜扩散。与它的P不同。绿脓杆菌对口，P 。恶臭 BifA不影响群运动。ΔbifA突变体的高粘附性表型与环状双鸟苷酸（c-di-GMP）水平，刚果红结合胞外多糖的产生以及粘附素编码lapA基因的转录的总体增加有关。EAL基序和修饰的GGDEF基序（与GGDQF改变）的完整性对于BifA活性至关重要，而ΔbifA突变体中异源c-di-GMP磷酸二酯酶的过表达会导致c-di-GMP耗尽，从而恢复了野生型生物膜的分散性和lapA表达。我们的结果表明，BifA是一种磷酸二酯酶，参与c-di-GMP池的调节，是产生低c-di-GMP信号（触发饥饿诱导的生物膜扩散）所必需的。