Isolation Of High Performance Bacterial Consortium And Analysis Of Its DGGE Fingerprints

Recently, with the rapid development of dye production and textile printing industry,amounts of biological toxic pollutants which was synthesized, high colority and refractory weredischarged. It caused a serious threat to the environment and health of human. Bacterialconsortium, which has more advantages than the single strain, such as stable effect anddegradation of dyes thoroughly. Screening and studying mixed flora which have excellentdecolorization performance will provide a theoretical basis for the biological treatment of dyewastewater in engineering application. In this study, six bacterial flora RTZ-1, RTZ-2, RTZ-3,RTZ-4, RTZ-5, RTZ-6capable of decoloring C.I. Direct Yellow12, C.I. Direct Red28, ReactiveTurquoise Blue KN-G, C.I. Reactive Blue KN-R, C.I Reactive5respectively has been screenedfrom the anaerobic reactor of a well-running textile printing wastewater biological treatmentsystem, through the method of domestication with gradient concentrations. We conducted a seriesof studies for the decolorization performance, decolorization mechanism and composition ofmicrobial communities.We studied the decolorization performance of the dye C.I. Direct Red28, C.I. Direct Yellow12, C.I. Reactive Blue KN-R, Reactive Turquoise Blue KN-G, C.I Reactive Black5and the mixeddyes by the flora RTZ-1, RTZ-2, RTZ-3, RTZ-4, RTZ-5, RTZ-6. Results of the dye decolorizationexperiments suggested that the flora RTZ-6could give an average decolorization rate of38.9%todegrade mixed dyes of200mg/L under the optimal culture conditions: temperature of35℃, pH of7.0and static culture with24h. It still had stable decolorization effect after one year. Under thesame culture conditions, the flora RTZ-1degraded more than90%of the C.I. Direct Red28of200mg/L on averange, the highest degrading rate is96.16%; the flora RTZ-2degraded more than90%of the C.I. Direct Yellow12of200mg/L on averange, the highest degrading rate is93.9%; theflora RTZ-3degraded more than70%of the C.I. Reactive Blue KN-R of50mg/L on averange, thehighest degrading rate is71.8%; the flora RTZ-4degraded more than60%of the ReactiveTurquoise Blue KN-G of50mg/L on averange, the highest degrading rate is68.2%; the floraRTZ-5degraded more than80%of the C.I Reactive Black5of50mg/L on averange, the highest degrading rate is86.3%.The optimum culture conditions of the flora RTZ-1, RTZ-2with high decolorization rate wasresearched. The functional consortium RTZ-1degrading the C.I. Direct Red28of200mg/Lshowed the highest degrading efficiency of96%at the culture conditions: pH=7.0, temperature of45℃, NaCl concentration of2mmol/L. The functional consortium RTZ-2degrading the C.I.Direct Yellow12of200mg/L showed the highest degrading efficiency of93%at the cultureconditions: pH=6.0, temperature of35℃, NaCl concentration of2mmol/L.In addition, the GC-MS was used to detect the degradation products after degrading for48hof the dye C.I. Direct Red28, C.I. Direct Yellow12, C.I. Reactive Blue KN-R, Reactive TurquoiseBlue KN-G, C.I Reactive Black5. We obtained the final degradation products after analysis. Thedegradation products of C.I. Direct Red28were3,4-Dihydroxybenzoic acid,3-(4-Hydroxyphenyl)–lactate. The degradation products of C.I. Direct Yellow12were3-Toluidine,4-Aminophenol,Tyrosol. The degradation products of C.I. Reactive Blue KN-R were DL-Alanine,D-a-Hydroxyisovaleric acid,4-Hydroxyphenethyl alcohol, Pathalic acid. The degradationproducts of Reactive Turquoise Blue KN-G were Lactic acid,4-Hydroxy-phenethyl alcohol. Thedegradation products of C.I Reactive Black5were3-Aminopropanoic,3-Hydroxybutyric acid,DL-Valine,(R)-2-Phenyllactic acid, Anthranilic acid.Finally, through denaturing gradient gel electrophoresis (DGGE) to analysis the compositionof microbial communities of the flora RTZ-1, RTZ-2, RTZ-3, RTZ-4, RTZ-5, RTZ-6, and thenanalyze the DGGE fingerprints. DGGE results showed that the six kinds of flora all containStreptococcus didelphis strain and Burkholderia sp as the main bacteria. The Streptococcusdidelphis strain belonged to Bacilli and the Burkholderia sp belonged to Betaproteobacteria. Theresults showed that Streptococcus didelphis strain and Burkholderia sp could degrade the fivedyes and the fixed dyes, they could also survive in the dyes. The Klebsiella sp is the main bacteriaof the flora RTZ-4, and it belonged to Gammaproteobacteria, the results showed that Klebsiella sphad a main effect to degrade the phthalocyanine dyes.