ABSTRACT
Biofilm formation is a dynamic process and different mechanisms are involved in attachment and growth (Kumar and Anand, 1998). Initially cells are deposited and then attach and grow into microcolonies and this involves the formation of extracellular polymers (EPS) which are thought to be essential in the process (Allison and Sutherland,
1987). There have been several reviews of biofilm formation in the food industry (Pontefract, 1991; Holah and Kearney, 1992; Mattila-Sandholm and Wirtanen, 1992; Carpentier and Cerf, 1993; Zottola and Sasahara, 1994; Kumar and Anand, 1998). Studies of attached cells and biofilms involving swabbing and traditional microbiology give an indication of the viable microorganisms present, but do not provide any information on biofilm structure or detect physiologically stressed cells such as viable non-cultumble (VNC) cells. Microscopy allows in situ analysis and numerous early studies used scanning electron microscopy (SEM) to study attachment (Zoltai et al., 1981; Schwach and Zottola, 1984; Speers et al., 1984; Stone and Zottola, 1985; Herald and Zottola, 1988; Mafu et al., 1990). However, SEM requires sample preparation that may introduce artefacts such as shrinkage of EPS and more recent studies have used alternatives such as low temperature SEM, environmental SEM, confocal microscopy and epifluorescence microscopy to assess attachment and biofilm formation (Holah et al., 1989; Little et al., 1991; Sutton et al., 1994; Hodgson et al., 1995).
