ABSTRACT
Ultraviolet light emitting diodes (UV-LEDs) are small mercury-free devices that can be installed at the point of use (POU) of water for disinfection. Considering that heterotrophic bacteria are of concern in drinking water systems, we applied a flow-through UV-LED apparatus to dechlorinated tap water, and determined the heterotrophic plate count (HPC) in samples after UV-LED exposure (UV+) compared to samples without UV-LED application (UV-). The UV+ and UV- samples were maintained at 20°C to track HPC profiles during storage for 7 days. It was confirmed that UV+ samples showed negative HPC or lower HPC than UV- for 5 days of storage after the flow-through test. HPC bacteria formed colonies with different morphological characteristics, and yellow colonies were closest to Novosphingobium sp., with 99% identity, while white and pale pink colonies were closest to Methylobacterium sp., with 99-100% identity, based on 16S rRNA gene sequences. White colonies became dominant in UV+, indicating that UV-LED exposure can select UV-resistant species such as Methylobacterium. This study shows the effects of UV-LED application on HPC bacteria in tap water and implies that future research is required on the significance and impacts of microbial selection by UV-LED exposure.
Subject(s)
Bacteria/radiation effects , Drinking Water/microbiology , Heterotrophic Processes , Ultraviolet Rays , Water Microbiology , Bacteria/genetics , Disinfection/methods , Phylogeny , RNA, Ribosomal, 16S/geneticsABSTRACT
BACKGROUND: Fibrin monomer (FM) and its complex (sFC) exist at high concentrations in hypercoagulable state blood. Two novel immunoassays for sFC (SF and FMC) using specific monoclonal antibodies (IF-43 and F405) were recently developed. METHODS: We measured the concentrations of thrombotic markers in 103 patients with DIC and thrombotic disorders. RESULTS: We found that the concentration of FMC was approximately 3.35-fold greater than that of SF. In patients with a high FMC/SF ratio, FDP and D dimer concentrations were increased, suggesting that the discrepancy in sFC concentrations was caused by fibrinolytic activity. Further, plasma samples from those patients were found to contain the X- and Y-fragments of FM in addition to FM and sFC in a Western blotting assay using F405, which binds with those fragments. In an in vitro study, FM formed from pooled plasma containing EDTA was degraded to the X- and Y-fragments of FM by fibrinolytic activity, and we termed those FM degradation products (FMDP). CONCLUSION: Determination of FMDP is important for diagnosis of thrombogenic conditions associated with fibrinolysis, such as in patients with DIC, and it may serve as a useful marker for hypercoagulable states with accelerated fibrinolysis.
