Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages.An aerobic bacterium(strain ZW) capable of degrading α-pinene was isolated from a biofilter by a selective enrichment.Based on the 16S rRNA gene analysis and physiochemical properties,this strain was identified as Pseudomonas veronii.Under the optimized condition achieved by the response surface methodology(RSM),as well as pH 6.82,temperature 26.3℃ and NaCl concentration 1.36%,almost 100% α-pinene could be removed within 45 hr.Enzymatic biodegradation by the crude intracellular enzyme could be described well by the Michaelis-Menten model in which the maximum degradation rate V max and the half-saturation constant K m were calculated to be 0.431 mmol/(L·min) and 0.169 mmol/L,respectively.Activity assay of catechol suggested that the strain ZW possessed a catechol1,2-dioxygenase and could decompose benzene-ring through ortho ring cleavage.Based on the identified intermediates by GC/MS,a new metabolic pathway was proposed,in which the final metabolites were some simpler organic and inorganic compounds.The present work demonstrated that the strain ZW would have a great application prospect for the remediation of α-pinene-contaminated environment.
Biofiltration is considered an effective method to control volatile organic compounds(VOCs) pollution.This study was conducted to evaluate the potential use of a bacterial biofilter packed with wood chips and peat for the removal of hydrophobic α-pinene.When inoculated with two pure degraders and adapted activated sludge,a removal efficiency(RE) of more than 95% was achieved after a startup period of 11 days.The maximum elimination capacity(EC) of 50 g/(m 3 ·hr) with RE of 94% was obtained at empty bed retention time(EBRT) of 102 sec.When higher α-pinene concentrations and shorter EBRTs were applied,the REs and ECs decreased significantly due to mass-transfer and biological reaction limitations.As deduced from the experimental results,approximately 74% of α-pinene were completely mineralized by the consortiums and the biomass yield was 0.60 g biomass/g α-pinene.Sequence analysis of the selected bands excised from denaturing gradient gel electrophoresis revealed that the inoculated pure cultures could be present during the whole operation,and others were closely related to bacteria being able to degrade hydrocarbons.The kinetic results demonstrated that the whole biofiltration for α-pinene was diffusion-limit controlled owing to its hydrophobic characteristics.These findings indicated that this bacterial biofiltration is a promising technology for the remediation of hydrophobic industrial waste gases containing α-pinene.
