Orlandi Viviana T, Bolognese Fabrizio, Chiodaroli Luca, Tolker-Nielsen Tim, Barbieri Paola
1Department of Theoretical and Applied Sciences, University of Insubria, Varese, Italy.
2Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Microbiology (Reading). 2015 Dec;161(12):2298-309. doi: 10.1099/mic.0.000193. Epub 2015 Sep 29.
Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of antibiotics and disinfectants. P. aeruginosa also displays a certain degree of tolerance to photodynamic therapy (PDT), an alternative antimicrobial approach exploiting a photo-oxidative stress induced by exogenous photosensitizers and visible light. To evaluate whether P. aeruginosa pigments can contribute to its relative tolerance to PDT, we analysed the response to this treatment of isogenic transposon mutants of P. aeruginosa PAO1 with altered pigmentation. In general, in the presence of pigments a higher tolerance to PDT-induced photo-oxidative stress was observed. Hyperproduction of pyomelanin makes the cells much more tolerant to stress caused by either radicals or singlet oxygen generated by different photosensitizers upon photoactivation. Phenazines, pyocyanin and phenazine-1-carboxylic acid, produced in different amounts depending on the cultural conditions, are able to counteract both types of PDT-elicited reactive oxygen species. Hyperproduction of pyoverdine, caused by a mutation in a quorum-sensing gene, rendered P. aeruginosa more tolerant to a photosensitizer that generates mainly singlet oxygen, although in this case the observed tolerance to photo-oxidative stress cannot be exclusively attributed to the presence of the pigment.
铜绿假单胞菌是一种机会致病菌，已知对不同种类的抗生素和消毒剂具有抗性。铜绿假单胞菌对光动力疗法（PDT）也表现出一定程度的耐受性，光动力疗法是一种利用外源性光敏剂和可见光诱导的光氧化应激的替代抗菌方法。为了评估铜绿假单胞菌的色素是否有助于其对光动力疗法的相对耐受性，我们分析了色素沉着改变的铜绿假单胞菌PAO1同基因转座子突变体对这种治疗的反应。一般来说，在有色素的情况下，观察到对光动力疗法诱导的光氧化应激具有更高的耐受性。脓黑素的过量产生使细胞对不同光敏剂光激活后产生的自由基或单线态氧所引起的应激更具耐受性。吩嗪、绿脓菌素和吩嗪 - 1 - 羧酸的产生量因培养条件而异，它们能够对抗两种由光动力疗法引发的活性氧。群体感应基因的突变导致绿脓菌素的过量产生，使铜绿假单胞菌对主要产生单线态氧的光敏剂更具耐受性，尽管在这种情况下观察到的对光氧化应激的耐受性不能完全归因于色素的存在。
