Biodegradation of Phenanthrene in Polycyclic Aromatic Hydrocarbon-Contaminated Wastewater Revealed by Coupling Cultivation-Dependent and -Independent Approaches

Abstract

The indigenous microorganisms responsible for degrading phenanthrene (PHE) in polycyclic aromatic hydrocarbons (PAHs)-contaminated wastewater were identified by DNA-based stable isotope probing (DNA-SIP). In addition to the well-known PHE degraders Acinetobacter and Sphingobium, Kouleothrix and Sandaracinobacter were found, for the first time, to be directly responsible for indigenous PHE biodegradation. Additionally, a novel PHE degrader, Acinetobacter tandoii sp. LJ-5, was identified by DNA-SIP and direct cultivation. This is the first report and reference to A. tandoii involved in the bioremediation of PAHs-contaminated water. A PAH-RHD gene involved in PHE metabolism was detected in the heavy fraction of C treatment, but the amplification of PAH-RHD gene failed in A. tandoii LJ-5. Instead, the strain contained catechol 1,2-dioxygenase and the alpha/beta subunits of protocatechuate 3,4-dioxygenase, indicating use of the β-ketoadipate pathway to degrade PHE and related aromatic compounds. These findings add to our current knowledge on microorganisms degrading PHE by combining cultivation-dependent and cultivation-independent approaches and provide deeper insight into the diversity of indigenous PHE-degrading communities.

Stable-Isotope Probing-Enabled Cultivation of the Indigenous Bacterium Ralstonia sp. Strain M1, Capable of Degrading Phenanthrene and Biphenyl in Industrial Wastewater

“…The increases in PHE or BP degradation efficiency with strain M1 were not significantly different between days 3 and 7 (Fig. 2d), a finding consistent with those of our previous study (12). This was possibly due to adverse conditions, such as toxic intermediates on the isolate, in the latter stage of incubation.…”

“…Their coexistence poses unacceptable risks to the environment and public health, challenging the efficiency of WWTPs (38,39). Conventional biological treatment is considered to be a cost-effective and ecofriendly approach for eliminating PAHs and PCBs from industrial wastewater (12,34,40). However, a major drawback of biological treatment is the fact that the majority of indigenous microbes responsible for degradation are not cultivable (16,41), and the active indigenous PAH or PCB degraders are difficult to isolate and study.…”

“…Each treatment was conducted in triplicate. All microcosms were incubated in the dark with shaking at 120 rpm and room temperature (ϳ25°C) as described previously (12). According to the analysis of residual PHE and BP, degradation efficiency was Ͼ60% on day 3 and Ͼ90% on day 6 ( Fig.…”

“…The extensive use and multiple sources of PAHs and PCBs make them ubiquitous in the environment and sometimes bioaccumulative (6). In industrial wastewater, PAHs and PCBs are normally present at levels that pose risks to ecosystems and public health, and remediation technologies (e.g., physicochemical methods and bioremediation) are therefore required to reduce their concentrations to acceptable levels or minimize exposure to receptors (9)(10)(11)(12).…”

Plant-bacteria synergism: An innovative approach for the remediation of crude oil-contaminated soils

“…Culture-independent approaches give molecular insights of the bacteria present in a particular site at a definite time (Gandolfi et al, 2017;Wang et al, 2017). Nucleic acids are also analyzed by way of fingerprinting of functional genes (e.g., alkB gene) or a quantitative PCR (qPCR) to reveal the presence of specific bacteria in an environment (Blain et al, 2017;Li et al, 2017).…”