Transcriptome analysis of Pseudomonas aeruginosa after MhqO dioxygenase treatment

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe chronic infections due to its exceptional ability to form a biofilm. Regulation of biofilm formation is very sophisticated and involves multiple bacterial systems and regulatory pathways. We found an enzyme MhqO dioxygenase from Bacillus paralicheniformis ZP1, which was effective in the inhibition of biofilm formation and disruption of mature biofilm of P. aeruginosa. Our results suggest that MhqO exerts its effect at the adhesion level, preventing cells from attaching to the surface. We have also shown that the enzyme stimulates the rhamnolipids synthesis. To elucidate the mechanism of enzyme action, we analyzed the transcriptome of the P. aeruginosa PAO1 strain treated with MhqO. Since cell adhesion occurs at the beginning of the stationary phase growth, the PAO1 strain was treated with MhqO for four hours, followed by total RNA isolation and cDNA synthesis. Transcriptome sequencing was performed by Illumina NovaSeq 6000 and data were analyzed by Novogene Bioinformatics Technology Co., Ltd. (Beijing, China). Obtained data showed that 122 genes were up-regulated, 41 genes were down-regulated, and the expression of 5947 genes was not changed. Five genes whose expression was altered are directly related to biofilm formation. MhqO increased the expression of the RsmA post-transcriptional regulator in P. aeruginosa. Transcriptome data revealed that pili IV biosynthesis genes were up-regulated, which is in accordance with literature data that RsmA positively regulates these genes. The inhibition of cells’ attachment to the surface could be explained by these results. In addition, RsmA positively regulates rhamnolipid production but negatively regulates biofilm matrix synthesis, which was supported by expression levels in the sequenced transcriptome. Data obtained from transcriptome analysis suggest that P. aeruginosa treated with MhqO dioxygenase should be more sensitive to oxidative and osmotic stress, as well as to beta-lactam antibiotics. Our further investigations should confirm these effects at the phenotypic level as well.