Diversity Of Utilizing Substrates Of Strain Dyella Sp.LA-4 And Its Application In Soi Remediation

The purpose of this dissertation is to investigate the broad spectum of substrate degradation by a biphenyl-degrading strain Dyella sp.LA-4 and its application in soil remediation.Under aerobic conditions,the characteristics of strain LA-4 degrading various aromatic compounds except biphenyl were investigated.Under anaerobic conditions,studies were carried out on the decolorization of azo dyes by strain LA-4.Finally,bioaugmentation of biphenyl-contaminated soil with strain LA-4 as augmented inoculums was studied,and the PCR-DGGE fingerprints analysis was used to reveal the structual changes of microbial community.Under aerobic conditions,strain LA-4 was able to grow on and degrade some simple aromatic compounds such as benzoic acid,catechol,aniline,hydroquinone,o-cresol,m-cresol;meanwhile,this strain could degrade polycylic aromatic hydrocarbons such as phenanthrene and naphthalin,but could not utilize heterocylic compounds and phenol,salicylic acid and nitrobenzene.Under anaerobic conditions,decolorization azo dyes by strain LA-4 were studied.The optimal conditions for the decolorizing activity of strain LA-4 was investigated using response surface methodology(RSM).It was indicated that strain LA-4 possessed the highest decolorizing activity under anaerobic conditions with inoculation amount 6.49%,pH 7.06 and temperature 29.15℃.And strain could grow and decolorize dye in the medium containing 3% NaCl;some ions such as Cu²⁺,Zn²⁺ could inhibit the decolorization rate,whereas Mg²⁺,Ca²⁺, Co³⁺,Fe³⁺,Mn²⁺ and Mg²⁺ had no effects on the decolorization rate;strain LA-4 could tolerate up to 1000mg/L Acid Red GR.Anthraquinone as a redox mediator could significantly accelerate the reduction process of azo dyes and the opitimal concentration of anthraquinone was 0.2g/L.Strain LA-4 was inoculated into biphenyl-contanminated soil,and the results showed that strain LA-4 could survive and enhance the biodegradation of biphenyl in contaminated soil;metal irons inhibit the bioremediation.The PCR-DGGE was used to reveal the structual changes of microbial community in the treatment system.The results showed that biphenyl-utilizing populations gradually increased to become the dominant species in the non-augmented syatem.However augmented system possessed more diversity of populations, in which strain LA-4 could persistent and co-exist well with the indigenous popilations in the augmented system.Microbial community are substantially changed and strain LA-4 was disappeared by adding metal ions.