Primary Research On The Mechanism Of Cytophaga Hutchinsonii Decomposing Cellulose

In the stage of "shortage of oil", the exploitation of renewable energy is being paid more attentation by governments. Biomass, which can take the place of oil as energy and material, has distinct differences from water power, wind power and solar power, which can just be used as energy. The full use of biomass resource will play an important role for the human society's sustainable development.Cellulose, the major component of cell wall of plant, is the most abundant renewable resource of biomass. Fuel ethanol production with biomass is thought to be one of the resources of ethanol production. However, because of the existence of crystalline cellulose, which is difficult to degrade, make ethanol production from biomass is less competible than gasoline at present.Some Cytophaga can "eat through" crystalline cellulose at poor nutrition conditions, but very little cellulase activity and glucose can be detected. This suggests that Cytophaga may have special system for the degradation of crystalline cellulose. But the mechanism of its degradation system is not yet clear. Cytophaga hutchinsonii had been listed in the program of microbial genomes by Department of Energy of the USA for its broad distribution in soil and no cellosomes. The work have been finished in 2005. The aim of our present work was to investigate the mechanism of Cytophaga hutchinsonii degradation of crystalline cellulose in the point of morphology, physiology and biochemistry.· There was a stage of three nucleoids in the single cell of Cytophaga hutchinsonii ATCC 33406, which was detected by fluorescent dye Hoechst 33342.· In batch culture, Cytophaga hutchinsonii ATCC 33406 was transformed into spherical cells from sinuous filaments with increasing age. The spherical cell is sensitive to osmotic pressure variation and loses the ability to utilize cellulose. The spherical cell is the degeneratiaon form of Cytophaga hutchinsonii ATCC 33406. It can be transformed into the delicate, flexible rod form which can degrade cellulose under proper conditions.· There is constitutive expression of CMCase (one type at least) in Cytophaga hutchinsonii ATCC 33406, with a molecule weight of 57700Da. This CMCase activity was detected in the cytoplasm, plasmalemma, periplasm, cell wall and extracellular fluid. The inducible CMCases (three types at least) are repressed by catabolite repression. The influence of glucose to the growth of Cytophaga hutchinsonii ATCC 33406 is correlated with the concentration of glucoses.· Fe³⁺ can accelerate the growth rate of Cytophaga hutchinsonii ATCC 33406 and Ca²⁺ has a negative effect on the secretion of extracellular CMCase.· When Cytophaga hutchinsonii ATCC 33406 was inoculated on the filter paper, it became very slim with a width of 0.145μm, which could penetrate the membrane filter (0.22μm) and degrade the cellulose below. There was no clear zone on cellulose if Cytophaga hutchinsonii did not penetrate the membrane filter. During the degradation of filter paper, a structure like plasmodesmata was found in Cytophaga hutchinsonii ATCC 33406.Through the research of morphology, physiology and biochemistry of C.hut during cultivation, the location and synthesis of CMCases were clarified. The contact between cell and celluloses which was necessary for the degradationg of cellulose was also studied. All this has a great meaning for the further investigation of cellulases system of Cytophaga hutchinsonii.