Isolation And Characterization Of A Sporocytophaga Sp. Strain

Cellulose is the most abundant and widely distributed macromolecular polysaccharide in nature,and is an important renewable resource and energy substance.Due to its crystal structure,cellulose is difficult to be degraded by biological enzymes,which seriously hinders the progress of its biotransformation.Excavation of new cellulose-degrading microorganisms and their degrading enzymes will help promote the development and utilization of cellulosic materials.Sporocytophaga sp.is a sliding bacterium that can be adsorbed and grown on the surface of cellulose and has high cellulose degradation ability.This thesis firstly optimized the purification method of spore-forming fibrinolytic bacteria.A strain of Sporocytophaga sp.CX11 was isolated and purified from a soil-derived microbial flora with high ability to degrade cellulose,and its properties were characterized.CX11 living cells have endoglucanase activity,and xylanase activity can be detected in the supernatant of the fermentation broth.The spore-forming fibrin has a special life history and has two forms of long rods and small cysts in the process of degrading cellulose.By studying the growth characteristics of strain CX11 on the filter paper solid medium,it was found that the long rod-shaped cells were more in the late growth stage,and the cells also had stronger cellulose degradation ability;while the small cysts were less in the middle growth stage of the strain.At the later stage,the degradation ability of the cells is greatly reduced.The adsorption level of cellulose by the spore-forming fibrinolytic bacteria largely determines its ability to degrade cellulose.It is found that CX11 in the late stage of logarithmic growth has the strongest adsorption capacity for cellulose.In addition,the polysaccharide,culture temperature and time on the cell surface have an effect on the ability of the strain to adsorb cellulose.This study also used liquid chromatography-mass spectrometry to analyze proteins with cellulose adsorption capacity in CX11 cells.Through NCBI comparison,A total of twelve proteins were obtained,including carbohydrate-binding protein,cellulase,nutrient uptake membrane protein,transport protein T9 SS secretion system protein and gliding motility protein.That laid the foundation for further study of the function of these proteins in cellulose degradation.In addition,this paper also studied the process of CX11 and other microorganisms synergistically degrading cellulose.The laboratory isolated and preserved Sphingomonas sp.CX7 was selected as the research object,and the live cells of the strain had exocellulase and ?-glucosidase activity.The experimental results show that CX11 and CX7 show synergistic effect on cellulose degradation when mixed culture.This synergistic effect may be due to the fact that the cellulase produced by CX7 compensates for the low capacity of CX11 to secrete cellulase,and CX7 utilizes the glucose produced in the fermentation broth,thereby relieving the feedback inhibition of cellulase by high concentration of glucose.The research in this thesis lays a foundation for further elucidating the mechanism of degradation of cellulose by Sporocytophaga sp.CX11,and also guides the direction of artificially constructing microbial communities that efficiently degrade cellulose.