Characterization of Zoogloea ramigera in biofilms

Zoogloea ramigera is an extracellular polymer-producing bacterium and forms flocs which include typical finger-like projections and amorphous flocs. Scanning electron microscopy (SEM) indicated that cells used the extracellular polymer as attachment sites and were embedded within the extracellular polymer. Finger-like projections which were similar to those from laboratory cultures of Z. ramigera were also found on the surface of sand which had raw sewage supplemented with phenol passed through them. Z. ramigera was isolated from raw sewage, mixed liquor suspended solids and lake water. The efficiency of Z. ramigera isolation was greatly increased by using m-toluic acid isolation medium combined with 1 mug/ml trimethoprim, and/or 10 mug/ml sulfadiazine.;Indirect immunoassay methods for the detection of Z. ramigera were developed using polyclonal antibodies against the cells or the isolated extracellular polymer of the neotype Z. ramigera strain 106 (ATCC 19544). The use of goat anti-rabbit IgG conjugated with FITC or biotin or colloidal gold as the secondary antibody allowed detection of Z. ramigera in environmental samples. These methods were also used as part of a most probable number (MPN) procedure to quantitate Z. ramigera at different stages of the wastewater treatment processes as well as in different lakes. It was found that the cells and the extracellular polymer of naturally occurring zoogloeal projections are antigenically and structurally related to those of Z. ramigera 106. Z. ramigera could be found in all stages of wastewater treatment processes, eutrophic lakes, mesotrophic lakes, and some oligotrophic lakes. The highest concentration of Z. ramigera was found in the mixed liquor stage of the two wastewater treatment plants in Gainesville, Florida.;By using bacterial 16S rRNA as template, and the primers specific for Z. ramigera 106 16S rRNA, RT-PCR was also used to identify Z. ramigera in biofilms from natural environments.;Zeta potential measurement indicated that overall surface charge of Z. ramigera was negative. Gas chromatography-mass spectrometry (GC/MS) analysis indicated the predominance of carbohydrate, especially amino sugars in the extracellular polymer produced by Z. ramigera. The use of MINT test following treatment of chlorine indicated that the extracellular polymer protected Z. ramigera cells from chlorine inactivation. This is true for Z. ramigera in both biofilms from natural environments and laboratory cultures.;Biofilms and other organic and inorganic materials in wastewater blocked positively charged sites on the surface of aluminum hydroxides coated sand. This loss of electropositive charge character was found to correspond to the decrease in removal efficiency of the two bacteriophages, which further supports the importance of electrostatic forces in virus-sand interaction.