Study On Isolation,Identification And Characteristics Of Bacteria For Decolorizing Cationic Blue SD-GSL

China is one of the main country for the production and use of cationic dyes,the annual dye production accounted for 20%³0%of the total output.Cationic dyes will run off easily in the process of producing and using them.The color of wastewater is as high as tens of thousands to hundreds of thousands.Theyare so difficult to biodegrade and decolorize because of complex aromatic groups,posing a serious burden on the environment.It is often necessary to use specific functional bacteria in order to achieve a good treatment effect.However,there are few types of existing cationic dye decolorizing bacteria,and they have strict requirements on the decolorization conditions,a long time required for achieving a good decoloring effect,and a limited tolerance for the dye concentration,which greatly limits its promotion and application.Therefore,finding microorganisms with strong adaptability and high-efficient decolorization performance for cationic dyes is of great significance for the further development of cationic dye biological treatment technology.In view of this,study focuses on the development of high-efficient decolorizing bacteria of cationic dyes,studies the decolorization characteristics and mechanism for providing reference and basis for the industrial application of the decolorizing bacteria.ZHT-3,ZHT-7 and ZHD-4 strain,with high-efficient decoloring Cationic Blue SD-GSL,were isolated fromsoil polluted by long-term industrial wastewaterand river mud beside the printing factory,dye concentration gradient pressurization was used to acclimatize and isolate decolorization bacterial strain for Cationic Blue.By means of the colony morphological characteristicsand homology comparison of 16S rDNA sequence,the strains ZHT-3,ZHT-7 and ZHD-4 were determined to be Bacilluscereus,Bacillus thuringiensis and Bacillus megaterium.The decolorization ability and the influencing factors of strains ZHT-3,ZHT-7and ZHD-4 were studied through Cationic Blue SD-GSL.The decolorization of cationic blue was completed in the logarithmic growth stage,comparing the growth and decolorization curves of strains ZHT-3,ZHT-7 and ZHD-4.The decolorization rate for 8 h were 86.3%,89.5%and 71.7%,respectively.The decolorization rate of ZHT-3 was attained 95%for 36 h with an increase in initial Cationic Blue concentration from 100 to 500 mg/L.Decolorizing bacteria required the participation of oxygen,the decolorization rate after continuous decolorization was still maintained at 79.2%,74.2%,and 73.1%,respectively.The strains ZHT-3 and ZHD-4 have good decolorization performance at pH 5⁸ and temperature 30⁴0°C,while the strain ZHT-7 has stronger adaptability,at pH 5⁹,temperature 25⁴0°C range.At the same metal ion concentration of 1 mmol/L,Mn²⁺inhibited the decolorization of the strain seriously,and Mg²⁺and Ca²⁺activated the decolorization at the initial stage of decolorization.Fe³⁺only had a promoting effect on strain ZHD-4.Extracellular metabolites（EM）and decolorization metabolites（DM）produced inhibition on the decolorization of three strains.They were significant differences in the degree of inhibition and duration of inhibition.The decolorization of strains ZHT-3,ZHT-7,and ZHD-4 was explored by comparison of decolorization of inactivated bacteria and live bacteria,determination of adsorption rate during decolorization,determination of the position of decolorizing enzymes,and analysis of ultraviolet and three-dimensional fluorescence spectra.The results showed that the biodegradation of the extracted intracellular crude enzyme and the extracellular enzymes contributed to the decolorization of cationic blue.The use of cationic blue-induced decolorizing bacteria before decolorization experiments had no significant effect on the decolorization of strains ZHT-3 and ZHD-4,but it could increase the decolorization rate of cationic blue in the initial stage of strain ZHT-7.