Analogue enrichment of aromatic degradation through application of lignin-derived phenols

  • Ibrahim Awache

Student thesis: Doctoral ThesisDoctor of Philosophy


This study employed analogue enrichment technique to stimulate the dominance of existing enzymatic activities of bacterial population responsible for degradation of polycyclic aromatic hydrocarbons (PAHs) in PAH-contaminated urban soils using naturally occurring lignin-derived phenols (13C-vanillin substrates). The influence of vanillin substrates on the 13C-signatures as identified on the 16S rRNA gene profiles present in the bacterial population were explored using metagenomic procedures _ primarily based on DNA stable isotope probing, coupled with Illumina sequencing of labelled DNA, and bioinformatics analysis (Kaiju, Hmmer and Krona). Naturally occurring lignin-derived phenols (vanillin) are found to have influence on the phylogenetic and functional genes of the diverse bacterial population responsible for degradation of naphthalene (and PAH other cocktails) in the PAH-contaminated urban soils. The bacterial population implicated in this study are primarily from the Proteobacteria, Actinobacteria and Terrabacteria phyla. Specifically, these bacteria are Sphingomonas spp, Sphingobium spp, Bradyrhizobium spp, and Brevundimonas spp. These group of bacteria are found to have naphthalene dioxygenase genes upon extrapolation with hmmer software package. This study can contribute effectively to the process of decontamination of polluted land; planning and execution of effective bio-stimulation regime for major ecological restoration enterprise and bioprospecting of useful genes useful for other applications.

Date of AwardDec 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsPetroleum Technology Development Fund
SupervisorMike Larkin (Supervisor), Deepak Kumaresan (Supervisor) & Christopher C R Allen (Supervisor)


  • Analogue
  • enrichment
  • PAH
  • vanillin
  • degradation
  • bacterial population
  • metagenomic procedures

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