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ROLES OF RESPIRATORY CHAIN ENZYMES IN BIOFILM FORMATION OF PSEUDOMONAS AERUGINOSA
Title
ROLES OF RESPIRATORY CHAIN ENZYMES IN BIOFILM FORMATION OF PSEUDOMONAS AERUGINOSA
Creator
DING, JIE
Date
2019
Description
Pseudomonas aeruginosa is a Gram-negative, rod-shaped bacterium, resistant to many antibiotics. It can cause several chronic infections such...
Show morePseudomonas aeruginosa is a Gram-negative, rod-shaped bacterium, resistant to many antibiotics. It can cause several chronic infections such as lung, bloodstream, urinary tract, and surgical wound infections. This bacterium produces biofilms which confer resistance to hazardous environments. P. aeruginosa contains five stages of colony development, which are planktonic attachment, cell to cell adhesion, proliferation, maturation, and dispersion. After five stages, biofilms of P. aeruginosa are matured. The biofilm structure produced by P. aeruginosa is important for cell survival, providing protection and resistance to harsh environment and antibiotics. In this research, the biofilms formed by wildtype strain PA01 and mutated strains of PA14, including NDH-2, NQR F, and NUO I, were developed in LB medium and Artificial Urine Medium separately for 96 hours. After washing, collecting, and staining the biofilms, the analyses of measurement of OD562 showed that in LB medium, PA01 formed more biofilms than mutants while NUO I and NDH2 had less biofilms, although not significantly. In AUM the situation was different. PA01 formed least biofilms while NQR F formed largest biofilms than any other strains. Also, the NDH-2 formed more biofilms than NUO I in AUM. The deficiencies of enzymes loss in those strains result in growing biofilm concentrations. Because the difference was not significant, we can only say that the NQR and NADH dehydrogenases have important roles in biofilm formation.
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SODIUM-BASED ENERGY METABOLISM AND DYNAMIC ENERGY DEPENDENCY OF CHLAMYDIA TRACHOMATIS
Title
SODIUM-BASED ENERGY METABOLISM AND DYNAMIC ENERGY DEPENDENCY OF CHLAMYDIA TRACHOMATIS
Creator
Liang, Pingdong
Date
2019
Description
Chlamydia trachomatis is an obligate intracellular bacterium that is responsible for various human diseases including trachoma, genital tract...
Show moreChlamydia trachomatis is an obligate intracellular bacterium that is responsible for various human diseases including trachoma, genital tract infections, and lymphogranuloma venereum. Energy metabolism consists many essential pathways to generate energy for every organism. However, it remains much unknown in C. trachomatis. For decades, C. trachomatis has been considered as an “energy parasite”, which needs the energy supply from the host cells entirely. In contrast, genomic studies show that this bacterium is capable of encoding enzymes that involve energy metabolism. However, no experimental data were provided to support the genomic information due to the peculiar developmental cycle of C. trachomatis inside the host cells. In this project, the oxidative phosphorylation pathway of C. trachomatis is first identified with experimental results. This pathway starts with the sodium pumping NADH:Ubiquinone oxidoreductase enzyme complex (NQR) transferring the electrons along the respiratory chain and generating a sodium gradient across the membrane. C. trachomatis contains an A-type ATPase that can utilize this sodium gradient to generate ATP. In vitro experiments in mammalian cells with different respiratory inhibitors show that C. trachomatis is not an obligate energy parasite. Instead, it has a dynamic energy dependency on the host metabolism that the bacterium switches from entirely to partially relying on the host energy metabolism for its energy requirement. The sodium gradient established by NQR and/or other transporters is of great importance to chlamydial metabolism. Further, the respiratory inhibitors test on interferon-γ-induced persistence of C. trachomatis in mammalian cell cultures shows that an inhibited energy metabolism prevents and eliminates the persistent form. This study provides new insights about antibiotics development and therapeutic methods against C. trachomatis infections.
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