Biodegradation of Polycyclic Aromatic Hydrocarbons in Mangrove Sediments Under Different Strategies: Natural Attenuation, Biostimulation, and Bioaugmentation with Rhodococcus erythropolis T902.1

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are pollutants that occur in mangrove sediments. Their removal by bacteria often depends on specific characteristics as the number of benzene rings they possess and their solubility. Their removal also depends on environmental factors, such as pH, temperature, oxygen, and the ability of the endogenous or exogenous microflora to metabolize hydrocarbons. With the aim of treating mangrove sediments polluted by hydrocarbons in a biological way, a biodegradation experiment was conducted using mangrove sediments artificially contaminated with a mixture of four PAHs. The study used Rhodococcus erythropolis as an exogenous bacterial strain in order to assess the biodegradation of the PAH mixture by natural attenuation, biostimulation, bioaugmentation, and a combination of biostimulation and bioaugmentation. The results showed that the last three treatments were more efficient than natural attenuation. The biostimulation/bioaugmentation combination proved to be the most effective PAH degradation treatment.

Optimization of an Autochthonous Bacterial Consortium Obtained from Beach Sediments for Bioremediation of Petroleum Hydrocarbons

“…was identified, previously enriched with a mixture of PAHs including naphthalene, anthracene, fluoranthene and pyrene, each in the concentration order of 10-30 mg•L −1 , revealed potential for PAHs degradation. Several other studies have highlighted the potential of species form the genera Pseudomonas, Rhodococcus erythropolis and Acinetobacter johnsonii to degrade PAHs compounds [55][56][57]. Nevertheless, in the present study, the mixture of PAHs was the carbon source that allowed a lower biomass growth and a lower abundance of hydrocarbons-degraders, when compared with acetate and petroleum.…”

Hydrocarbon Removal by Two Differently Developed Microbial Inoculants and Comparing Their Actions with Biostimulation Treatment

“…The proper selection of bacterial strains is always a crucial step, and well-known hydrocarbon degraders may succeed or fail depending on the environment they are introduced to [11,32]. In favorable conditions, bioaugmentation with even a single strain resulted in the effective removal of hydrocarbons [61] and even within one species, one could find a difference among individual strains in this regard [62].…”

Cellular Modifications of Rhodococci Exposed to Separate and Combined Effects of Pharmaceutical Pollutants

“…In our previous studies, we observed biodegradation of pharmaceutical pollutants by bacteria of the genus Rhodococcus (class Actinomycetia)-a group of extremely tolerant mycolic acid-containing nocardioform actinomycetes, which are structurally, physiologically, and biochemically fit for decomposition of lipophilic organic compounds. Rhodococci are among the dominant microorganisms in anthropogenically disturbed biotopes and also participate in their restoration [14][15][16][17][18]. The ubiquity and localization of Rhodococcus spp.…”