AWWA WQTC69478

This powerpoint presentation begins by providing a brief overview of nematodes and protection mechanisms of microorganisms in ultraviolet (UV) disinfection. Research objectives included the following: assess the significance of nematodes interms of protecting waterbornepathogens against UV disinfection usingE. coli OP50 - GFP as a surrogate forenteropathogenic bacteria, and B. subtilis spores as a possible surrogatefor Cryptosporidium. Study designincluded the following: synchronized nematodes (adults); bacterial strains ofE. coli OP50 - GFP andB. subtilis spores ATCC 6633;Chlorination - 10 ppm * 5 min for E. coli, and15 ppm * 20 min for B. subtilis spores; Sonication: 15 W * 60 sec in 5 ml;UV exposure - collimated beam apparatus, LP, 254 nm, 2 UV fluences: 5 - 40 mJ/cm²;culture medium for bacterial counts - m-Endo for E. coli, andTSB for B. subtilis spores. Presentation conclusions indicate the following:internalization by nematode C. elegans offers significantprotection to bacteria (E. coli, B. subtilis spores) against UVdisinfection at typical fluence applied in WTP (40 mJ/cm²); thus, the authors suppose that pathogenic microorganisms indrinking water could survive UV disinfection treatment whenprotected inside nematodes;this should be taken into account when assessing themicrobial risk associated to drinking water; however, the low concentration of pathogenicmicroorganisms in most drinking water sources suggeststhat pathogen ingestion by higher organisms in naturalconditions remains a low probability event; and,while higher organisms are known to be ubiquitous indrinking water systems, studies are lacking in terms ofquantification of internalized pathogen occurrence in fieldconditions. Includes 2 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2008

Number of Pages:

26

File Size:

1 file , 1.5 MB