Study On Isolation And Kinetics Of Phenol-Degrading Bacteria

Phenolic compounds are common contaminants in wastewater, being generated from petroleum, coal conversion and pharmaceutical industries. Phenols are considered as priority pollutants since they are harmful to organisms and human at low concentrations. So, many researches have been focus on finding an effective and low-cost way to deal with this kind of wastewater. Compared with physical and chemical methods, microorganism biodegradation of phenol wastewater is more effective, environment friendly and without secondary pollution. At present, the biological treatment technology is in the transitional period from mixed culture to pure culture, so isolation and identification of phenol-degrading bacteria are very important.In this paper, two strains named KN4, KN7were isolated and identified from wastewater by using the traditional microorganism breeding technology. KN4, KN7were identified as Pseudomonas sp and Bacillus subtilis by physiological, biochemical and16S rDNA identification. B. subtilis has never been reported. Then optimizing the factors impacting phenol biodegradation by KN4and KN7were explored.The phenols biodegradation were contrastively studied between B. subtilis and Pseudomonas sp, B. subtilis showed more efficient to degrade substrates than Pseudomonas sp. The ability of bacteria for phenol degradation and foster environmental degradationability were examined by shake flask method and degradation rate was conducted by HPLC. Fifteen phenolic compounds were studied, B. subtilis could degrade60mg/L phenol completely within24hours and300mg/L p-nitrophenol within48hours. It also had strong ability to degrade single chlorine substituted phenols.A Haldane model for substrate utilization was also able to describe the trends in p-nitrophenol transformation, excellent agreement was obtained between the model predictions using experimentally estimated parameter values and the experimental data for the synchronous disappearance of p-nitrophenol. Biodegradation could bring two kinds of mostly intermediate products and the product had evident process that they were degraded after accumulation. The metabolic pathway was considered as the hydroxyquinol pathway.In summary, Phenol degradation bacteria which isolated from wastewater could be valuable in practice, especially the action of strain KN7to substituted phenols degradation, but the exact mechanism need to further exploration.