“…They also produce gliding gonidia, form rosettes and have the ability to deposit intracellular sulfur granules (Larkin & Strohl, 1983;Williams & Unz, 1985a, b;Williams et al, 1987). Thiothrix species are found in a number of habitats, ranging from sulfide-containing natural waters (Brigmon et al, 1994a;Jones et al, 1982;McGlannan & Makemson, 1990) and irrigation systems (Ford & Tucker, 1975) to activated-sludge wastewater-treatment plants, where their presence in large numbers contributes to the problem of filamentous sludge bulking (Brigmon et al, 1994b;Eikelboom, 1975;Tandoi et al, 1994;Wagner et al, 1994;Williams & Unz, 1985a). The involvement of Thiothrix species as causative organisms of filamentous sludge bulking in wastewatertreatment plants has led to studies of their physiology (Richard et al, 1985;Williams & Unz, 1985a, b ;Tandoi et al, 1994), ultrastructure (Brigmon et al, 1994b ;Williams et al, 1987), growth characteristics and interactions with heavy nietals (Shuttleworth & Unz, 1991.…”