Scholarship & Research
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/1
Browse
4 results
Search Results
Item Ecology of Legionella pneumophila biofilms: The link between transcriptional activity and the biphasic cycle(Elsevier BV, 2024-06) Barbosa, Ana; Azevedo, Nuno F.; Goeres, Darla M.; Cerqueira, LauraThere has been considerable discussion regarding the environmental life cycle of Legionella pneumophila and its virulence potential in natural and man-made water systems. On the other hand, the bacterium's morphogenetic mechanisms within host cells (amoeba and macrophages) have been well documented and are linked to its ability to transition from a non-virulent, replicative state to an infectious, transmissive state. Although the morphogenetic mechanisms associated with the formation and detachment of the L. pneumophila biofilm have also been described, the capacity of the bacteria to multiply extracellularly is not generally accepted. However, several studies have shown genetic pathways within the biofilm that resemble intracellular mechanisms. Understanding the functionality of L. pneumophila cells within a biofilm is fundamental for assessing the ecology and evaluating how the biofilm architecture influences L. pneumophila survival and persistence in water systems. This manuscript provides an overview of the biphasic cycle of L. pneumophila and its implications in associated intracellular mechanisms in amoeba. It also examines the molecular pathways and gene regulation involved in L. pneumophila biofilm formation and dissemination. A holistic analysis of the transcriptional activities in L. pneumophila biofilms is provided, combining the information of intracellular mechanisms in a comprehensive outline. Furthermore, this review discusses the techniques that can be used to study the morphogenetic states of the bacteria within biofilms, at the single cell and population levels.Item Ecology of Legionella pneumophila biofilms: The link between transcriptional activity and the biphasic cycle(Elsevier BV, 2024-06) Barbosa, Ana; Azevedo, Nuno F.; Goeres, Darla M.; Cerqueira, LauraThere has been considerable discussion regarding the environmental life cycle of Legionella pneumophila and its virulence potential in natural and man-made water systems. On the other hand, the bacterium's morphogenetic mechanisms within host cells (amoeba and macrophages) have been well documented and are linked to its ability to transition from a non-virulent, replicative state to an infectious, transmissive state. Although the morphogenetic mechanisms associated with the formation and detachment of the L. pneumophila biofilm have also been described, the capacity of the bacteria to multiply extracellularly is not generally accepted. However, several studies have shown genetic pathways within the biofilm that resemble intracellular mechanisms. Understanding the functionality of L. pneumophila cells within a biofilm is fundamental for assessing the ecology and evaluating how the biofilm architecture influences L. pneumophila survival and persistence in water systems. This manuscript provides an overview of the biphasic cycle of L. pneumophila and its implications in associated intracellular mechanisms in amoeba. It also examines the molecular pathways and gene regulation involved in L. pneumophila biofilm formation and dissemination. A holistic analysis of the transcriptional activities in L. pneumophila biofilms is provided, combining the information of intracellular mechanisms in a comprehensive outline. Furthermore, this review discusses the techniques that can be used to study the morphogenetic states of the bacteria within biofilms, at the single cell and population levels.Item Effects of culture conditions on the susceptibility of Legionella pneumophila to iodine disinfection(Montana State University - Bozeman, College of Agriculture, 1991) Cargill, Kari LisaItem Development of fluorescent in situ hybridization for detection of L. pneumophila using solid phase laser cytometry(Montana State University - Bozeman, College of Letters & Science, 2013) Lim, Kien Seng; Chairperson, Graduate Committee: Barry H. PyleLegionella pneumophila was first identified and documented after a pneumonia outbreak during an American Legion convention held in Philadelphia in 1976, with 25 casualties. L. pneumophila is a gram negative bacillus found mostly in fresh water environments. It is known as a facultative intracellular parasite of protozoa in its natural habitat, and can also infect macrophages in humans when contaminated aerosols are inhaled. The current detection procedure for L. pneumophila is a culture based method, which is slow and may not detect viable but non-culturable cells; presence of L. pneumophila usually takes 3 to 10 days to confirm by this method, due to its slow growth. New more reliable, rapid and sensitive methods are needed. In this research, a method coupling fluorescent in situ hybridization (FISH) and ScanRDI solid phase laser cytometry was developed to detect L. pneumophila relying on growth with extended incubation to obtain cultures. Published FISH methods were optimized by addition of HCl and Tween 20 incubation, dextran sulfate, helper probes and tyramide signal amplification to increase fluorescence intensity of probed L. pneumophila. ScanRDI settings were also adjusted to be able to detect TSA-FISH probed L. pneumophila. The resulting TSA-FISH method coupled with ScanRDI was able to detect almost 90% of L. pneumophila cell compared to plate counts. This optimized TSA-FISH method was also used on Escherichia coli and Aeromonas hydrophila; the ScanRDI detected 79.5% and 39.7% of these organisms respectively compared to plate counts. The results suggested that L. pneumophila can be detected and enumerated using the method developed in this research. It can be completed within 12 hours, which is a significant improvement compared to at least 3 days for current detection methods. The TSA-FISH method can be used for detection and enumeration of at least 2 microorganisms, L. pneumophila and E. coli. For reliable detection and enumeration of other organisms such as A. hydrophila, procedures need to be further optimized and ScanRDI settings adjusted for each organism. It is anticipated that several microbes could be detected on one membrane filter using appropriate probes, procedures and ScanRDI settings.