Sotomayor Martínez, Carolay H.

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    Advanced detection and monitoring of chemical and microbial agents in water reclamation systems
    (2024-07-12) Sotomayor Martínez, Carolay H.; De Jesús Ruiz, Marco A.; College of Arts and Sciences - Sciences; Hernández Rivera, Samuel P.; Tarafa Vélez, Pedro J.; Department of Chemistry; Resto Irizarry, Pedro J.
    Biofilms are a community of bacterial microorganisms attached to the surface or interface with each other, usually protected with an extracellular matrix that is produced by themselves, and that grow on inert or living surfaces. From an environmental and health perspective, a series of problems arise at a general level and in space flights, related to hygiene and disinfection, putting at risk the health of the crew and the infrastructure of the space station because once a biofilm reaches its state of maturity, the excreted extracellular substances facilitate its attachment to the surface and function as a stable and robust chemical barrier, which become impervious to antibiotics and chemical treatment. Therefore, assessing and monitoring microbial contamination during long-term human spaceflight is important, as it can damage instrumentation and life support systems. The main objective of this research was based on assessing and monitoring microbial contamination during long-term human spaceflight is important in developing new nano-biotechnological approaches to evaluate the performance of the water recovery process of a 2-stage urine filtration unit applied to space missions. This research used Escherichia coli, Staphylococcus aureus, Salmonella, Lactobacillus acidophilus, casei, and lactis as model microorganisms. To carry out this study, Raman spectroscopy was implemented as part of the diagnostic protocols that aid in the detection, characterization, and identification of microbial strains. Sensing surfaces were sandpaper of silicium carbide with a grit size in the 2000-5000 range (8-4µm particle size) and its microstructured cast on polydimethylsiloxane (µPDMS). The surface area of µPDMS 2000 (8µm) was effectively used for the detection of L. acidophilus, casei, and lactis. Whereas the surface of µPDMS 5000(4µm) was used for the detection of E. coli, S. aureus, and Salmonella since it yielded superior results, the process of biofilm formation and its potential biofouling effect on target membranes was assessed over 16 generations, using time intervals of 0.5, 2, 6 and 8 hours. Multivariate analysis of spectroscopic data was used to evaluate changes in the characteristic bands of microbial building blocks: a. DNA (1587, 781-730 cm-1), b. polysaccharides (1580 and 1290-1030 cm-1), c. lipids (1730, 1490-1470 cm-1), d. proteins (1650-1600 cm-1), were used to confirm the presence or absence of the different microorganisms in the waste and at each stage of the filtration process.