Enhanced phenol biodegradation by Burkholderia PHL 5 with the assistant of nitrogen

Phenol, which is a typical recalcitrant refractory organic poses a severe hazard to ecosystems even at low concentrations. Although numerous bio-approaches have been dedicated to eliminate the contamination coupling with denitrifying, the interactive mechanism and relationship remain poorly understood. In this study, a strain identified as Burkholderia PHL5 with efficient phenol degrade capacity was isolated from activated sludge. During the degradation process, most of the phenol (44.36%) was mineralized, while 36.79% phenol was assimilated by the strain and only 18.85% phenol was degraded to long-chain organic compounds. Also, phenol degradation was accompanied by the formation of catechol, mediated by the multicomponent phenol hydroxylase (LmPH) initially, which could be corroborated by the amplification of the functional LmPH gene. Two vital long-chain organics intermediates, namely, bis(6-ethyl-3-octanyl) oxalate and 6-ethyl-3-octanyl 4-methylpentyl oxalate, were identified in the degradation process, indicating that phenol underwent meta-ring opening cleavage pathway mediated by the strain. Moreover, the biodegradation of phenol by the strain was found to be an N-dependent process, whereas the nitrate could exacerbate the phenol degradation rather than acting exclusively as the electron acceptor and nitrogen source. Lastly, a positive relationship of initial phenol concentration and phenol vs. nitrate ratio on phenol degradation was discerned. Overall, these findings deepened the understanding of recalcitrant refractory organic degradation, thereby providing an eco-friendly strategy for the decontamination of the targeted contaminant in an application.

Automated summary

In this study, a Burkholderia PHL5 strain with efficient phenol degradation capacity was isolated from activated sludge, and its degradation mechanism and performance were investigated. The strain was found to mineralize, assimilate, and degrade phenol into long-chain organic compounds, with the formation of catechol mediated by specific enzymes. Moreover, the strain was able to degrade phenol through a meta-ring opening cleavage pathway, producing two important organic intermediates. It was also observed that the degradation process of phenol by the strain was dependent on nitrogen, and nitrate could enhance phenol degradation. The initial phenol concentration and phenol vs. nitrate ratio were found to have a positive impact on phenol degradation.