The biofilm formation and the alginate biosynthetic genes expression of a Pseudomonas aeruginosa strain with a new type mucA gene mutation
Objective To identify the mutation point of Pseudomonas aeruginosa strain PA17 and to investigate the alginate biosynthetic genes expression during biofilm formation. Methods The mucA gene of PA17 was amplified and the products were sequenced. A modified plate culture method was used to establish the biofilm model of PA17. Semi-quantitative RT-PCR was used to determine the expression level of algD, algU and algR during the biofilm formation. One-Way ANOVA was used to identify the significance of the difference. Scanning electron microscope was used to observe the biofilm structure. Results There was a 166-333 deletion mutation and 342 A→G in mucA gene of PA17. The expression level of algD and algU was maximal at the 6 d time point during biofilm formation but the expression level of algR was maximal at 24 h time point. The expression difference of algD, algU and algR in different time point of biofilm formation had statistic significance. PA17 biofilm was mature after 6 d and the biofilm structure is a pellicle-shaped one. Conclusion PA17 is a mucoid Pseudomonas aeruginosa strain with a new type of mutation of mucA gene, and the expression difference of alginate biosynthetic genes of this strain in different time points of biofilm formation had statistic significance, the biofilm structure of PA17 is a pellicle-shaped one.