During growth of P. curdlanolyticus B-6 on Berg’s mineral salt medium containing 0.5% xylan as carbon sources, the protein concentration in the medium was low up to the late stationary growth phase. CMCase and xylanase activities could be detected in the culture medium after the late exponential phase (Pason et al., 2006b). At the declining growth phase, the extracellular xylanase and CMCase rapidly increased due to the release of enzymes from the cell surfaces into the culture medium. These phenomena were different from the growth patterns of other aerobic bacteria, which grew and produced extracellular enzymes into culture supernatant immediately, but similar to those of the anaerobic bacteria which produced multienzyme complexes (cellulosomes) around the cell surfaces and adhered to these substrates and secreted into culture supernatant later (Bayer & Lamed, 1986; Lamed & Bayer, 1988). The observation of cell surfaces at the late exponential growth phase by scanning electron microscopy (SEM) revealed that the cells adhered to xylan (Fig. 5A), similar to the cells of the cellulosome producing anaerobic bacterium, C. thermocellum, which is a cell associated entity that mediates the adhesion of the bacterium to cellulose (Lamed et al., 1987; Mayer et al., 1987), whereas the surface of the cells of strain B-6 at the late stationary growth phase lacked such structures because the multienzyme complex was released into the medium from the cell surfaces (Fig. 5B). In addition, the pattern of multienzyme complex in the culture medium at the late stationary growth phase was determined. Native-polyacrylamide gel electrophoresis (native-PAGE) exhibited a high molecular weight band at the top of the gel (Fig. 6, lane 1). This protein band was dissociated into major and minor components through treatment by boiling in sodium dodecyl sulphate (SDS) solution, showing at least 18 proteins with molecular masses in the range of 29 to 280 kDa (Fig. 6, lane 2). Among those protein bands, at least 15 bands showed xylanase activities (Fig. 6, lane 3) and at least 9 bands showed CMCase activities (Fig. 6, lane 4) on zymograms. These multiple cellulases and xylanases are assembled into the high molecular weight complexes and released from the cell surfaces into medium at the late stationary growth phase. In C. thermocellum, the cellulosome consisted of many different types of glycosyl hydrolases, including cellulases, hemicellulases, and carbohydrate esterases, which served to promote their synergistic action (Lamed et al., 1983). These evidences confirm that the strain B-6 can produce xylanolytic-cellulolytic enzyme system that exists as multienzyme complex under aerobic conditions.