Miron, J., Metabolic Unit, Volcani Center, Bet Dagan, Israel, Metabolic Unit, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan, 50250, Israel
Jacobovitch, J., Metabolic Unit, Volcani Center, Bet Dagan, Israel
Bayer, E.A., Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
Lamed, R., Center for Biotechnology, Tel Aviv University, Israel
Morrison, M., Metabolic Unit, Volcani Center, Bet Dagan, Israel
Ben-Ghedalia, D., Department of Animal Science, Ohio State University, United States

Aims: To compare the subcellular distribution of glycanase-related components between wild-type Ruminococcus albus SY3 and an adhesion-defective mutant, to identify their possible contribution to the adhesion process, and to determine their association with cellulosome-like complexes. Methods and Results: Cell fractionation revealed that most of the cellulases and xylanases were associated with capsular and cell-wall fractions. SDS-PAGE and gel filtration indicated that most of the bacterial enzyme activity was not integrated into cellulosome-like complexes. The adhesion-defective mutant produced significantly less (5- to 10-fold) overall glycanase activity, and the 'true cellulase activity' appeared to be entirely confined to the cell membrane fractions. Antibodies specific for the cellulosomal scaffoldin of Clostridium thermocellum recognized a single 240 kDa band in R. albus SY3. Conclusions: The adhesion-defective mutant appeared to be blocked in exocellular transport of enzymes involved in true cellulase activity. A potential cellulosomal scaffoldin candidate was identified in R. albus SY3. Significance and Impact of the Study: Several glycanase-related proteins and more than one mechanism appear to be involved in the adhesion of R. albus SY3 to cellulose.