Presence of several cellulose-binding proteins in cell lysate of Fibrobacter succinogenes s85.

Abstract

Attempts were made to analyze the substances involved in the adhesion of cells of F. succinogenes S85 to cellulose. Firstly, the effect of the treatment of the cells with enzymes on their adhering ability to cellulose was examined. Treatment of cells with proteolytic enzymes such as proteinase K, thermolysin, protease Type IV and trypsin, and with lipase reduced markedly their adhering ability to cellulose, whereas their adhering ability to cellulose was not affected by treatment with acid phosphatase, DNase 1, RNase A and RNase T1. These results show that some proteins on the cell surface are involved in the adhesion of cells to cellulose. Next, attempts were made to detect some of the proteins capable of adhering to cellulose in cell lysate of the bacterium. After Avicel cellulose was incubated in the cell lysate of the bacterium at 37°C, cellulose was washed several times with buffer containing Softes 12 as a detergent to remove the cell debris and proteins incapable of adhering to cellulose. Proteins strongly adhering to cellulose after washing were eluted with buffers containing 1% carboxymethylcellulose (CMC) or 10% cellobiose. When the proteins eluted with CMC were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), one major band and many minor bands were detected in the gel. When the proteins eluted with cellobiose were analyzed by SDS-PAGE, one major band, one minor band and two faint bands were detected in the gel. The major protein in both eluents using CMC or cellobiose, exhibited the same molecular weight of approximately 120 kilodaltons (kDa). These CBPs in cells of the bacterium disappeared after treatment with proteinase K, whereas these CBPs in cells remained after treatment with lipase.