Construction and phenotypic study of Pseudomonas aeruginosa inducibly expressing a ferric uptake regulator / 生物工程学报

Members of the ferric uptake regulator (Fur) protein family are bacterial transcriptional repressors that control iron uptake and storage in response to iron availability, thereby playing a crucial role in the maintenance of iron homeostasis. The fur null mutants of Pseudomonas aeruginosa could not be obtained because fur is an essential gene. In this study, We constructed a Fur inducibly expression strain Δfur/attB::PBAD-fur in order to study the effect of fur on the growth, biofilm formation, motilities and oxidative stress response of P. aeruginosa. The results showed that a low level of fur expression retarded the growth of P. aeruginosa at an iron-depleted condition, or under high concentration of iron, or in the presence of H2O2. Fur affected the biofilm formation and the motilities (swimming, twitching, and swarming) of strain PAO1. The production of pyoverdine is regulated by Fur. Interestingly, proteins from Magnetospirillum gryphiswaldense MSR-1, which shares homology with Fur, can partially recover the pyoverdine production of strain Δfur/attB::PBAD-fur. This study provides new clues for the prevention and treatment of P. aeruginosa infections.

Preface for special issue on biofilm and c-di-GMP--Microbial society, c-di-GMP regulation, and new research techniques / 生物工程学报

Biofilm is prevalent in various ecological niches, in which microbial cells interconnect with each other through extracellular polymeric substances including polysaccharides, extracellular DNA, and proteins. When living in biofilms, the microbial cells employ small signalling chemicals as their "language" to communicate mutually, and exhibit remarkable differences in physiology compared to those living in planktonic state. It has been proven that the development of biofilm is subject to the regulation of c-di-GMP, an important second messenger found in prokaryotes. Given its important roles of biofilms in microbial infection, industry application, plant-microbe interactions and environmental pollustion, biofilm is one of frontier research areas in microbiology. This special issue of "Biofilm and c-di-GMP" systematically reviews the current progresses in the multiple research frontiers, including biotechnology, infectious diseases, environmental microbiology and plant pathology, with special focus on the methods and techniques in biofilm research. We hope that the issue will boost the interest of students and young scientists in this exciting area of microbiology.

Anti-biofilm effects of Zn lactate·3H₂O and SnF₂ on Pseudomonas aeruginosa, Acinetobacter baumannii and Streptococcus mutans / 生物工程学报

Zn lactate and SnF₂ were used as active compounds in the dentifrice. Here, their anti-biofilm effects were evaluated on Pseudomonas aeruginosa, Acinetobacter baumannii and Streptococcus mutans. The biofilm prevention/dispersal assay of P. aeruginosa PAO1 demonstrated that Zn lactate and SnF₂ can inhibit biofilm formation independently or by combined treatment. Zn lactate disrupted extracellular polysaccharides matrix formation and SnF₂ reduced the biomass of biofilm. Most importantly, the combination of Zn lactate and SnF₂ thoroughly abolished the biofilm formation of all three strains.

Iron uptake and biofilm formation in Pseudomonas aeruginosa / 生物工程学报

Biofilms are surface-associated communities of microorganisms embedded within self-secreted extracellular polymeric substances, and a major cause of chronic and persistent infections. Respiratory Pseudomona aeruginosa infection is the leading reason for morbidity and mortality in cystic fibrosis patients. The formation of biofilms by P. aeruginosa in the airway is thought to increase persistence and antibiotic resistance during infection. Biofilm formation of P. aeruginosa is regulated by complicated signaling systems including quorum sensing and two-component systems that control the synthesis of extracellular polymeric substances. Furthermore, iron is an essential and scarce nutrient for bacteria and an important signal factor. P. aeruginosa has developed multiple iron uptake systems to sequester enough iron for its survival, with important regulatory roles in both release of virulence factors and formation of biofilms. In this review, we summarize recent advances in biofilm formation and its regulation along with the iron-uptake strategies in P. aeruginosa, to provide new insights and understanding to fight bacterial biofilms.