Pseudomonas Strains For Potential Degrading Ability Of Aromatic Compounds

Aromatic compounds are abundant and structurally diverse in nature.They are important bioresources which make up 25 % of land plant biomass and widely used as raw materials or intermediates in industry.On the other hand,aromatic compounds are wide-spread pollutants with long retention time and hard to degrade.Study of aromatic compounds degradation is significant for utilization of aromatic biomass and pollution issues.Pseudomonas strains are widely distributed in soil,water,plant and human body and survive under a great variety of conditions.Their great degrading ability of organics and substrate resistant ability make themselves a promising option for aromatic compounds metabolism,especially Pseudomonas putida.Exploiting the ability of Pseudomonas strains to utilize aromatic compounds contributes to handling worsening environmental crisis and utilizing aromatic compounds efficiently.53 Pseudomonas strains whose complete genomes have been sequenced were selected to analyse their ability to degrade aromatic compounds using a comparative genomic approach.Results indicated that Pseudomonas have a overall strong degrading ability of aromatic compounds and this ability is not confined in single strain but widely distributed in Pseudomonas strains.This diversity may result from the activity of Pseudomonas genomes and frequent horizontal gene transfer may play a significant role in gaining degrading ability.Insert sequences and immune abilities of Pseudomonas were analysed to comfirm the rationality of the speculations.Pathways of ferulic acid degradation in Pseudomonas have been studied in detail.In the most common one ferulic acid is degraded to vanillin catalyzed by Feruloyl-CoA-synthetase and Enoyl-CoA-hydratase.As plant secondary metabolite,ferulic acid is a promising option for vanillin synthesis but few strains are competent for industrialization.Researchers have focused on gene modification of bacteria such as Pseudomonas and Escherichia coli for vanillin production.Several possible genes related to ferulic acid degradation were selected by analysis of Pseudomonas putida B6-2 genomic data.RT-qPCR analysis revealed the transcriptional levels of adhA,adhB,adhD,vdh of P.putida B6-2 in ferulic acid medium were 5.0,5.5,6.8,3.9 fold of those in the glycerol medium.The mutant strains can all use ferulic acid as the sole carbon.The mutant strain V1 can accumulate vanillin up to 0.1 g/L temporarily and other mutant strains acculated other metabolites instead of vanillin.