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EFFECT OF METABOLIC INHIBITORS ON GROWTH AND BIOFILM DEVELOPMENT OF ENTEROBACTER AEROGENES AND KLEBSIELLA PNEUMONIAE
Title
EFFECT OF METABOLIC INHIBITORS ON GROWTH AND BIOFILM DEVELOPMENT OF ENTEROBACTER AEROGENES AND KLEBSIELLA PNEUMONIAE
Creator
Sanjana, Krithica
Date
2017, 2017-05
Description
Enterobacter aerogenes and Klebsiella pneumoniae are the leading cause of severe hospital-acquired infections across the globe, particularly...
Show moreEnterobacter aerogenes and Klebsiella pneumoniae are the leading cause of severe hospital-acquired infections across the globe, particularly in the US and Europe. These bacteria contribute heavily to the alarming threat of emergence of multiple drug resistant strains, enabling them to survive a wide spectrum of antibiotics. One of the key factors involved in drug resistance is the production of biofilms, a complex exopolysaccharide matrix that acts as a protective component and increase their resistance to external factors including antibiotics. In this study, we described that targeting the bacterial respiratory metabolism entirely disrupts pathways used for energy synthesis and substantially inhibits bacterial growth. Moreover, the metabolic inhibitors decreased the production of biofilms by these bacteria. Two key factors being the bacterial growth and biofilm development were analyzed in this research study. The data indicates that HQNO has the highest inhibition effect which targets essential enzyme complex Na+-NQR in bacterial growth as well as biofilm formation. Thus, the structure of HQNO can potentially be suited for new antibiotic development to combat the problem of multidrug resistant bacteria.
M.S. in Biology, May 2017
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SYNERGISTIC EFFECT OF FATTY ACIDS AND NISIN IN INHIBITING PERSISTER AND BIOFILM OF LISTERIA MONOCYTOGENES
Title
SYNERGISTIC EFFECT OF FATTY ACIDS AND NISIN IN INHIBITING PERSISTER AND BIOFILM OF LISTERIA MONOCYTOGENES
Creator
Zhou, Jiacheng
Date
2019
Description
A foodborne pathogen Listeria monocytogenes causes a life-threatening listeriosis in humans after eating contaminated food. The FDA-approved...
Show moreA foodborne pathogen Listeria monocytogenes causes a life-threatening listeriosis in humans after eating contaminated food. The FDA-approved antimicrobial peptide nisin has been used to prevent contamination of food product from Gram-positive pathogens including L. monocytogenes. However, the formation of biofilms and persisters (i.e., metabolically dormant bacterial population) has resulted in the failure of nisin treatment. Fatty acids, which have been known to exhibit antimicrobial activities, are widely used for therapeutics, food preservation, and agriculture. Previously, we found that two fatty acid compounds lauric acids and N-tridecanoic acids are effective in inhibiting biofilms and persister formation of Gram-negative pathogens. In this study, we investigate whether the fatty acid treatment in combination with nisin promotes inactivation of L. monocytogenes, especially biofilms and persisters. The fatty acid-only treatment reduced the level of biofilms and persisters, while nisin-only treatment resulted in the development of resistant population of L. monocytogenes ATCC19115 strain. However, the co-treatment of the fatty acid and nisin synergistically enhanced the killing of L. monocytogenes by significantly decreasing the number of survived cells and inhibiting biofilms. These results are particularly important in improving food safety in that the food-grade fatty acids can be applied to repress the occurrence of resistant mechanisms of foodborne pathogens by inhibiting biofilm and persister cell formation.
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EFFECT OF METABOLIC INHIBITION ON THE GROWTH AND BIOFILM PRODUCTION OF VIBRIO CHOLERAE AND PSEUDOMONAS AERUGINOSA
Title
EFFECT OF METABOLIC INHIBITION ON THE GROWTH AND BIOFILM PRODUCTION OF VIBRIO CHOLERAE AND PSEUDOMONAS AERUGINOSA
Creator
Bunn, Dakota C.
Date
2017, 2017-05
Description
V. cholerae is a gastrointestinal pathogen which causes extreme watery diarrhea and results in over 120,000 deaths per year worldwide. It is...
Show moreV. cholerae is a gastrointestinal pathogen which causes extreme watery diarrhea and results in over 120,000 deaths per year worldwide. It is especially prevalent in developing countries that lack proper water treatment and in areas struck by natural disasters such as hurricanes. P. aeruginosa is an opportunistic pathogen that is ubiquitous in nature, and increasingly found in hospitals burn wards, sinks, catheters and other surgical equipment. Both bacteria are developing increased antibiotic resistance through several mechanisms, with one of the most common ones being the formation of a complex exopolysaccharide matrix known as a biofilm. In this study, using metabolic inhibition, we determined that Na+-NQR is essential for the growth of V. cholerae and P. aeruginosa in both nutrient rich and physiological conditions. We were also able to confirm that inhibition of this enzyme, in both growth conditions, resulted in decreased biofilm production, subsequently eliminating one of the main mechanisms for antibiotic resistance of these bacteria.
M.S. in Biology, May 2017
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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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DEVELOPING FUSION BACTERIOCINS FOR ERADICATING PSEUDOMONAS AERUGINOSA BIOFILMS
Title
DEVELOPING FUSION BACTERIOCINS FOR ERADICATING PSEUDOMONAS AERUGINOSA BIOFILMS
Creator
An, Sungjun
Date
2022
Description
The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality in cystic fibrosis patients and...
Show moreThe opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality in cystic fibrosis patients and immunocompromised individuals. Due to its remarkable ability to resist antibiotics, eradicating P. aeruginosa has become increasingly difficult. As previously reported, we have successfully engineered a colicin-secretion system that kills target biofilm cells rapidly and selectively in multispecies biofilms as well as demonstrated the potential of using live microorganisms engineered to produce antimicrobial colicin protein to treat biofilm-associated infections. In this study,we constructed a fusion colicin-pyocin that could target P. aeruginosa by DNase activity of colicin E2. The newly engineered bacteriocin-secretion system upon the shift in target, maintained biofilm inhibition capacity. Both during biofilm formation and after its development, the system was able to suppress the P. aeruginosa biofilm. This result opened up the possibility that it could be used for novel live biotherapeutics. A further study was conducted to overcome the challenge of requiring an exogenous inducer. We applied the concept of Quorum-Sensing signal that recognize autoinducer as a trigger of fusion colicin-pyocin producing genetic circuit so that it automates the production and secretion of fusion colicin-pyocin as soon as the genetic circuit senses the target population growing. This study demonstrated that combining the domains of colicin and pyocin could broaden the genetic circuit target range, maintaining strain specificity, while employing the QS system could remove the fundamental problem of diffusion or degradation of extra compounds as they approach engineered cells.
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