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IDENTIFICATION OF A FLAVOBACTERIUM STRAIN VIRULENT AGAINT GIARDIA LAMBLIA CYSTS
Citation:
Rodgers, M R., D J. Flanigan, B. K. Kinkle, AND S Pfaller. IDENTIFICATION OF A FLAVOBACTERIUM STRAIN VIRULENT AGAINT GIARDIA LAMBLIA CYSTS. WORLD JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY 19(7):703-709, (2003).
Impact/Purpose:
Investigate the occurrence of Aeromonas bacteria in potable water derived from both surface and ground water sources. Develop improved method(s) for the detection of culturable H. pylori in environmental samples and investigate the occurrence of H. pylori in potable waters.
Description:
We have isolated a bacterial strain capable of killing the cyst form of Giardia lamblia, from a Kentucky stream. This bacterium, designated Sun4, is a Gram negative, aerobic rod which produces a yellow pigment, but not of the flexirubin-type. Although true gliding motility has not been observed in Sun4, this strain does exhibit a spreading colony morphology when grown on low nutrient agar. Strain Sun4 has been identified by 16S rRNA sequencing and phylogenetic analysis as belonging to the genus Flavobacterium, and is most closely related to Cytophaga sp. strain Type 0092 and associated Flavobacterium columnare strains. Lipid analysis also identified fatty acids characteristic of the Cytophaga-Flavobacterium group of bacteria. In culture, Sun4 is able to degrade casein and cellulose, but not chitin, gelatin, starch, or agar. Degradation of Giardia cysts by Sun4 appears to require direct cellular contact as neither cell-free extracts nor cells separated from the cysts by dialysis membranes showed any activity against cysts. In addition, Giardia cysts are killed more effectively by Sun4 growing in static versus shaking cultures. Activity against Giardia cysts is rapid, with Sun4 killing over 90% of cysts within 48 hours. Strain Sun4 requires elevated levels of Ca2+ for optimal growth and degradative activity against Giardia cysts. We propose that bacterial strains such as Sun4 could be used as biological control agents against Giardia cysts in drinking water treatment systems.