2.2. Wastewater sample processing
A total of 100 ml of each sample was filtered through a 150 mm
pre-filter (#1001-150, Whatman International Ltd., Maidstone England)
and a GMF grade 0.2 mm filter (#1842-090, Whatman). Both
filters were vortexed (high setting) in 10 ml of phosphate buffered
saline (PBS; pH 7. X) to release particulates from the filters. The
filters were removed, and the suspension was centrifuged at
14 900 g for 10 min. All but 3.0 ml of supernatantwas removed by
aspiration. The pellet was suspended by vortexing (high setting),
and the suspension was used for DNA extraction, enumeration of
fecal coliforms, and isolation of A. butzleri.