Screening, Mutagenesis And Immobilization Of Effective Phenol-degrading Strains

Phenol is an important raw material or intermediates of petroleum industry,paper industry, agriculture and pharmaceutical industry. However, it is also the mainpollutants industrial wastewater. Phenol is a kind of aromatic compounds, toxic anddifficult to degrade. With the socio-economic development and industrialization,untreated phenolic wastewater cause serious environmental pollution and threatenhuman health. Therefore, it is necessary to remove phenol from industrial effluents.Compared with traditional physical and chemical methods, method of phenolicwastewater biodegradation is economic and effective with no secondary pollution.In this study, with phenol as the sole source of carbon, phenol-degradingmicrobes were isolated from rotting wood and polluted sludge. These strains wereidentified as Acinetobacter sp. SD1，Pseudomonas sp. SD2and Rhodococcus sp. SD3according to their morphological feature and16S rDNA sequence, respectively. Thephenol-degrading performance of Rhodococcus sp. SD3strain was best among threestrains, which almost completely degraded1.0g/L phenol in72hours.Rhodococcus sp. SD3was mutated by using LiCl as a chemical mutation agent.After mutation, the strain could degrade99.77%of1.5g/L phenol within72h. Theresults showed that the inoculation of the mutant was no less than2%forphenol-degradation. The suitable temperature for phenol-degradation ranged from30℃to35℃. The optimum pH was from7.0to8.0.The degradation of phenol occursmainly from48h to72h in the logarithm phase.With sodium alginate (SA)-polyvinyl alcohol (PVA) as the carrier, the mutantwas immobilized. The results showed the immobilized strain could degrade99.66%ofphenol for the first time use. The phenol-degradation efficiency exceeded99%for thesubsequent three times use.Thus, the mutant was effectively protected by sodiumalginate (SA)-polyvinyl alcohol (PVA) and repeated use of immobilized cell isfeasible.In conclusion, the new strain for effective phenol degradation was screened andmutated in the study.The mutant was also immobilized for the repeated reuse. Theresults paved a road for the bioremediation of wastewater.