Screening Of High-phenol-tolerance Strain And Studying Of Its Phenol-degrading Abilities

Phenol and its derivatives existed widely in wastewater and waste gas from coking,oil refining, paper making, chemical, plastic, oil industries, and so on, and could causethe inhibition of growth and degradation ability of microorganism in active sludge,therefore, most coking wastewater after biochemical treatment cannot satisfy theemission standard, but dosing coking wastewater with high resistance of phenol strainswas helpful to improve the COD removal efficiency. In a word it is an importantsignificance to screen high resistance of special strains in phenolic wastewatertreatment.We isolated high-phenol-tolerance strain from the activated sludge of coking plantwastewater, and studied the strain’s best growth conditions, its growth and degradationcharacteristics with phenol and catechol as a sole carbon source respectively, as well asextraction, isolation, identification of phenol metabolism product. The results were asfollows:(1) Liquid culture enrichment and spread-plate method were employed to isolateand screen a strain N2from the activated sludge of coking plant wastewater in fuping ofshan’xi province, which could tolerant2000mg/L phenol, as well as growth situationwas the best, the phenol degradation rate was the biggest. The strain was identified by16S rDNA gene sequencing method as Pseudomonas stutzeri N2.(2) When the Pseudomonas stutzeri N2grew on phenol as a sole carbon source,fast cell growth and phenol transformation were carried out simultaneously. ThePseudomonas stutzeri N2was cultured under pH=7.5,30℃, ammonium nitrate was thenitrogen source conditions, when the initial concentrations of phenol were within50mg/L~400mg/L, the removal efficiency of phenol was100%in30hours. When the initial concentration of phenol were within800mg/L~900mg/L, there are three cellgrowth periods, fast growth, retarding growth, and inferior fast growth, occurred in timeorder and correspondingly. Within the time in fast growth periods and retarding growthperiods, the transformation rate of phenol is low, only less than5%, while thetransforming rate within the inferior fast growth periods was increased from5%to100%quickly.(3) Carbon source was different, the phenol degradation activity of Pseudomonasstutzeri N2was also different. When the Pseudomonas stutzeri N2was grown on beefextract-peptone, the phenol degradation activity was the biggest, with the inoculationamount was5%, the phenol degradation rates were59%with200mg/L phenol for4hours.(4) The Pseudomonas stutzeri N2was also able to grow on catechol as a solecarbon source and energy. When the initial concentration of catechol were within200mg/L~400mg/L,800mg/L,1000mg/L, the catechol degradation rates were100%for12hours,59hours,71hours respectively. The degradation of phenol and catechol byPseudomonas stutzeri N2both coincided with zero-order reaction.(5) Following the gas chromatography/mass spectrometry (GC/MS) analysis, fourintermediates of phenol degradation by Pseudomonas stutzeri N2were detected:catechol, hydroquinone,3,4-dihydroxybenzoate and4-hydroxybenzoate. Pseudomonasstutzeri N2degradated phenol though carboxylation metabolic pathway.The results were expected to provide data and test methods in the Pseudomonasstutzeri N2’s application to phenolic wastewater treatment.