The Biodegradation Of Naphthalene And1-Naphthoi

With the continuous development of social industrialization, theenvironment around the world have been varying degrees of pollution, at thesame time people’s environmental protection consciousness graduallystrengthened, the protection and preservation of our home is our everyone’sresponsibility. Because of the dangers to organisms and the environment,polycyclic aromatic hydrocarbons and their derivatives is more and moreattention. Due to screening difficult and adaptting to the scope of a single andless speciesthe，the advantage bacterium which degraded polycyclic aromatichydrocarbons and their derivatives are difficult to apply. The free bacteria inwastewater treatment is easy to loss, and cause secondary pollution. Theproblem of immobilized easy agglomeration is also need to solve. This topicselected the advantage of degradation of polycyclic aromatic hydrocarbons andtheir derivatives strains through domestication of coking wastewater in theactivated sludge, screening, separation, and mixed with CMC-bentonite gel asthe carrier by embedding method. Free bacteria after fixation was applied to theprocess of adsorption and degradation of naphthalene and1-naphthol research,in order to provide theoretical basis for the study of the biodegradation of polycyclic aromatic hydrocarbons and their derivatives. The main researchcontent is as follows:At first，this topic got the strains by concentration gradient domesticationmethod, and then optimize the immobilized particles, respectively investigatesthe influence of the CMC concentration, the additive amount of bentonite andAlCl3concentration on particle properties.Then studied the degradation effect offree N bacteria and fixed particles by the best of the preparation.The researchresults show that the degradation of naphthalene N bacteria were gram-negativebacteria.Immobilized particle is the best preparation conditions:3%CMCconcentration,5%bentonite additive quantity and2%AlCl3concentration, andcrosslinking time of1h.Under30℃, and130rpm, with6%of the quantity ofN bacteria100mL40mg/L completely degradation of naphthalene in18h. Theresults showed that the immobilized beads degrading naphthalene consisted offour steps: adsorption-desorption-re-adsorption-biodegradation, and therewas a corresponding relation between the four steps and the growth of bacteriain the immobilized beads. The optimum experimental conditions were of6%(V/Vaqueous sol) suspension without the nutritional treatment,40mg/L of the initialnaphthalene concentration and30℃. Naphthalene was degraded to theundetectable level in32h. The reuse of the immobilized beads allows us to get10cycles. During the reusing process, the tolerance and biological activity ofthe immobilized beads were greatly enhanced, and the naphthalene degradationrate was almost remained unchanged at100%. In the research on the degradation of1-naphthol, examines the effect of NPbacteria to the degradation of1-naphthol, and after introduced into N bacteria,the effect of joining way and the proportion between NP and N bacteria.Through the LC-MS analysis,1-naphthol possible degradation pathway werespeculated.The results show that by the strain identification, NP bacteria isMyroides odoratimimus which is very rare. Under30℃,4mL NP wet bacteriato degradation100mL30mg/L1-naphthol into intermediary metabolites within2d,and degradation rate is91%, intermediate metabolites of ultravioletabsorption peak is252nm. N bacteria was jioned in the reaction of NP bacteriaafter2d, absorption peak in UV disappeared after6d, which could be thoughtthat1-naphthol was degradated to small molecules by free NP and N bacteriacompound,and the degradation rate was100%. Under the condition of4mL NPbacteria, with the increase of concentration of1-naphthol, the amount of Nbacteria was in the form of index increased. NP and N bacteria to1:1afterfixation can convert different concentrations of1-naphthol to intermediatemetabolites, but which could not effectively degraded intermediate metabolites.The intermediate metabolites of1-naphthol analysised by LC-MS, andconcluded that intermediate metabolites may consist of four, namely1,2-Dihydroxynaphthalene、1-Hydroxy-1,2-dihydronaphthalene、2-Carboxyhydrocinnamic acid、6-hydroxy-3-Heptened ioic.According to the characteristics of the enzyme catalytic speculation,1-naphthol degradation pathways maybe as fallow: First，under the action of hydroxylase，1-naphthol was metabolised to1,2-Dihydroxynaphthalene, then2-Carboxyhydrocinnamic acid by the dioxygenaseand reductase (dehydrogenase) into，then further opening loop，broken bondunder the function of the two-plus oxygen enzyme、reductase and otherenzymes， into6-hydroxy-3-Heptenedioic. Later both N and NP bacteriametabolised1-naphthol for some small molecules.Second, the1-naphthol are still under the action of hydroxylase metabolismfor1,2-Dihydroxynaphthalene, then the dioxygenase through twice completelyopened loop and translated under the metabolism action of reductase and otherenzymes as6-hydroxy-3-Heptenedioic.Three, there are tautomerism between1-naphthol and naphthoquinone, andnaphthoquinone metabolised1-Hydroxy-1,2-dihydronaphthalene under reductase.