Strategies to increase bioavailability and uptake of hydrocarbons

12 páginas.-- 50 referenciasThe biodegradation of hydrocarbons in the environment is often slow due to restricted bioavailability. Research performed during the last 20 years has shown possible pathways to increase the bioavailability of hydrocarbons without necessarily increasing the risk to the environment. Pollutant solubilization through (bio)surfactants, microbial transport, and attachment to pollutant interfaces can increase bioavailability, which translates into an enhancement of biodegradation rates. These strategies can not only be integrated into optimized bioremediation protocols that lead to lower decontamination endpoints in soils and sediments but also help to improve biodegradation in other environmental contexts, such as wastewater treatment and natural attenuation.This study was supported by the Spanish Ministry of Science and Innovation (CGL2013-44554-R and CGL2016-77497-R), the Andalusian Government (RNM 2337), and the European Commission (LIFE15 ENV/IT/000396).Peer reviewe

Why Biodegradable Chemicals Persist in the Environment?:A Look at Bioavailability

Biodegradable chemicals may become persistent due to reductions in their bioavailability thereby impacting on the rate and extent of biodegradation in soils and sediments. This chapter examines this – commonly neglected – contradictory face of persistence assessments from the light of the latest advancements in bioavailability science. They include the microbial influences on bioavailability, the different sorption capacities of carbonaceous components of soils and sediments, and the dissimilar bioavailability shown by chemicals when they are present as non-extractable residues. We also discuss possible pathways to improve the realism in persistence assessments from standardized biodegradation tests by incorporating new bioavailability-based approaches. Innovations of the standard tests are possible through the modified chemical application of enhanced dispersion and passive dosing. In addition, we offer a proposal for integrating bioavailability measurements into standard simulation tests with soils and sediments, by using desorption extraction and passive sampling methods to assess the removal of the bioavailable fractions, in addition to the total extractable concentration of the chemical. © 2020, Springer Nature Switzerland AG

Surfactant-induced bacterial community changes correlated with increased polycyclic aromatic hydrocarbon degradation in contaminated soil

Bioremediation as a method for removing polycyclic aromatic hydrocarbons (PAHs) from contaminated environments has been criticized for poor removal of potentially carcinogenic but less bioavailable high-molecular-weight (HMW) compounds. As a partial remedy to this constraint, we studied surfactant addition at sub-micellar concentrations to contaminated soil to enhance the biodegradation of PAHs remaining after conventional aerobic bioremediation. We demonstrated increased removal of 4- and 5-ring PAHs using two nonionic surfactants, polyoxyethylene(4)lauryl ether (Brij 30) and polyoxyethylene sorbitol hexaoleate (POESH), and analyzed bacterial community shifts associated with those conditions. Eight groups of abundant bacteria were implicated as potentially being involved in increased HMW PAH removal. A group of unclassified Alphaproteobacteria and members of the Phenylobacterium genus in particular showed significantly increased relative abundance in the two conditions exhibiting increased PAH removal. Other implicated groups included members of the Sediminibacterium, Terrimonas, Acidovorax, and Luteimonas genera, as well as uncharacterized organisms within the families Chitinophagaceae and Bradyrhizobiaceae. Targeted isolation identified a subset of the community likely using the surfactants as a growth substrate but few of the isolates exhibited PAH-degradation capability. Isolates recovered from the Acidovorax and uncharacterized Bradyrhizobiaceae groups suggest the abundance of those groups may have been attributable to growth on surfactants. Understanding the specific bacteria responsible for HMW PAH removal in natural and engineered systems and their response to stimuli such as surfactant amendment may improve bioremediation efficacy during treatment of contaminated environmental media