Location, formation and biosynthetic regulation of cellulases in the gliding bacteria Cytophaga hutchinsonii

• Published in: International journal of molecular sciences 2006-01, Vol.7 (1), p.1-11
• Main Authors: Louime, Clifford, Abazinge, Michael, Johnson, Elijah
• Format: Article
• Language: English
• Subjects: Bacteria; Carbon; Cell Adhesion; Cellulase; Cellulose; Cytophaga; Enzyme Regulation and Suppression; Enzymes; Glucose; Microorganisms; Organisms; Proteins
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/i7010001

An analysis of the recently published genome sequence of Cytophagahutchinsonii revealed an unusual collection of genes for an organism that can attackcrystalline cellulose. Consequently, questions were being raised by cellulase scientists, as towhat mechanism this organism uses to degrade its insoluble substrates. Cellulose, being ahighly polymeric compound and insoluble in water, cannot enter the cell walls ofmicroorganisms. Cellulose-degrading enzymes have therefore to be located on the surface ofthe cell wall or released extracellularly. The location of most cellulase enzymes has beenstudied. However, basic information on C. hutchinsonii cellulases is almost non-existent. Inthe present study, the location, formation and biosynthetic regulation of cellulases in C.hutchinsonii were demonstrated on different substrates. Various fractions isolated from C.hutchinsonii after cell rupture were assayed for carboxymethyl-cellulase activity (CMC).The cellulases were found to be predominantly cell-free during active growth on solka-flok,although 30% of activity was recorded on cell-bound enzymes. Relatively little CM-cellulase was formed when cells were grown on glucose and cellobiose. Apparently glucoseor labile substrates such as cellobiose seem to repress the formation of CM-cellulase. Thesefindings should provide some insight into possible hydrolysis mechanisms by C.hutchinsonii.