[Show abstract][Hide abstract] ABSTRACT: Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen that causes serious diseases in pigs and humans. GdpP protein is a recently discovered specific phosphodiesterase that degrades cyclic diadenosine monophosphate (c-di-AMP). It is widely distributed among the firmicutes phylum and is related to several phenotypes in various bacterial strains. We investigated the role of GdpP in physiology and virulence in SS2 HA9801. The in-frame mutant of gdpP was constructed using homologous recombination and bacterial growth, biofilm formation, hemolytic activity, cell adherence and invasion, expression of virulence factors, and virulence were evaluated. Disruption of gdpP increased intracellular c-di-AMP level and affected growth and increased biofilm formation of SS2. Simultaneously, the gdpP mutant strain exhibited a significant decrease in hemolytic activity and adherence to and invasion of HEp-2 cells compared with the parental strain. Quantitative reverse transcriptase polymerase chain reaction indicated significantly reduced expression of the known virulence genes cps2, sly, fpbs, mrp, ef and gdh in the gdpP mutant. In murine infection models, the gdpP mutant strain was attenuated, and impaired bacterial growth was observed in specific organs. All these findings revealed a significant contribution of gdpP and its substrate (c-di-AMP) to the biology and virulence of SS2.
Preview · Article · Sep 2014 · Microbiological Research
[Show abstract][Hide abstract] ABSTRACT: To further enhance the bacterial removal capability, we synthesize a biotemplated hierarchical porous material coupling chemical components and hierarchical microstructure, which is derived from rice husk. The results show that the chemical components and hierarchical microstructure of the prepared material could both be factors in enhancing bacterial removal capability. Based on the experimental results, we propose a hypothetical enhanced bacterial removal mechanism model of the prepared material. Furthermore, we propose a hypothetical method of inferring bacterial physical removal effects of samples by their dye adsorption results. And the hypothetical method has been proven to be reasonable by the experimental results. This work provides a new paradigm for bacterial removal and can contribute to the development of new functional materials for enhanced bacterial removal in the future.
No preview · Article · Feb 2014 · ACS Applied Materials & Interfaces
[Show abstract][Hide abstract] ABSTRACT: Addressing the problem of pathogenic bacteria in human health remains a great challenge. We have prepared MgO, replicated from the leaf template, for efficient bacterial removal. The synthesis method perfectly inherits the advantage of the hierarchical three-level micro-meso-macroporous structure from the leaf template. The final product has the integrated advantages of a positively charged property, hierarchical three-level micro-meso-macroporous microstructure and sterilization property so that it could be named "the positively charged leaf". The positively charged leaf with the microstructure, which is bestowed by Nature, could be utilized in water purification for dye removal and could be extended to pollutant removal, especially of harmful bacteria. The positively charged leaf, as the leaf shield, could be useful in protecting human health. The concept of this work could be applied to the synthesis of different functional metal oxides with hierarchical porous structures, and the products could be utilized in efficient bacterial removal.
No preview · Article · Apr 2013 · Chemistry - A European Journal