Genetic diversity of phenol hydroxylase-encoding genes among wastewater sludge bacteria

Tan WA, Kusuma F. 2021. Genetic diversity of phenol hydroxylase-encoding genes among wastewater sludge bacteria. Biodiversitas 22: 4291-4297. Phenol is a toxic aromatic compound that is used in various industries. In this study, we explore the molecular diversity of bacterial genes that encode for phenol hydroxylase, a key enzyme for phenol degradation, within sludge samples collected from the aeration and microbial recovery tank of an automotive wastewater treatment system. Partial phenol hydroxylase-encoding gene (600 bp) was amplified from the total DNA of each tank using a degenerate primer pair and cloned to construct a gene library. A total of 37 and 38 clones were obtained from the aeration and microbial recovery tank, respectively. The clones were sequenced and compared to GenBank database using BLASTX, followed by neighbor joining-based phylogenetic analysis using MEGA7. A majority of the clones recovered from both tanks belonged to Betaproteobacteria, which have been reported as phenol degraders with various metabolic activities and lifestyles. The clones are grouped into eight clusters. Six clusters were present in both the aeration and microbial recovery tank, and one unique cluster was identified in each tank. This indicated that diverse microbial communities play a role in phenol-containing wastewater treatment. They may have changed throughout the process as the surrounding chemical compositions differed and a variety of metabolic roles surfaced.