Effect of low concentrations of synthetic surfactants on polycyclic aromatic hydrocarbons (PAH) biodegradation

Abstract

The present study is focused on the effect of synthetic surfactants, at low concentration, on the kinetics of polycyclic aromatic hydrocarbons (PAH) biodegradation by Pseudomonas putida ATCC 17514 and addresses the specific issue of the effect of the surfactant on bacterial adhesion to PAH, which is believed to be an important mechanism for the uptake of hydrophobic compounds. For that purpose, three surfactants were tested, namely, the nonionic Tween 20, the anionic sodium dodecyl sulphate (SDS) and the cationic surfactant cetyltrymethyl ammonium bromide (CTAB). Data showed that the effect of each surfactant on the ability of strain ATCC 17514 to biodegrade fluoranthene and anthracene and to use them as growth substrate varied considerably. Tween 20, at a concentration of 0.08 mM, increased the biodegradation rate of fluoranthene and doubled the maximum specific biodegradation rate of anthracene. The presence of SDS, at a concentration of 0.35 mM, led to a reduction of 50% on the biodegradation rate of fluoranthene, but doubled the removal rate of the more hydrophobic anthracene (0.3 mg L À1 h À1). Finally, CTAB, at a concentration of 0.27 mM, had a negative effect on the biodegradation of both PAH, leading to an abrupt decrease on the biomass growth.

Surfactant effects on biodegradation of polycyclic aromatic hydrocarbons

“…Similar results were reported by Deschênes et al anthracene degradation in soil has not increased by SDS addition [16]. A decrease in anthracene degradation by P. putida was observed in the presence of SDS and CTAB [17]. Bautista et al study revealed that Tween 80 increases naphthalene and anthracene degradation by Pseudomonas sp., Enterobacter sp., Stenotrophomonas sp.…”

“…So, it is very important to choose the correct combination between the micro-organisms, the PAHs substrate and surfactant molecule [17].…”

Influence of soil contamination with PAH on microbial community dynamics and expression level of genes responsible for biodegradation of PAH and production of rhamnolipids

“…The ability to stimulate the biodegradation of PAHs by the use of surfactants has been confirmed by numerous researchers and is associated, e.g., with the mechanisms of increasing the bioavailability of hydrophobic compounds by their emulsification and/or solubilization, or altering the properties of the microorganisms cell surfaces (Ławniczak et al 2013). Rodrigues et al (2013) have reported that low concentrations of surfactants not only stimulated the decomposition of anthracene and fluoranthene but also indicated that the effect varied depending on the type and concentration of surfactant and the type of PAHs. An exceedingly high concentration or the wrong choice of surfactant can be toxic toward to microorganisms cells, resulting in a decrease of their number and, consequently, lower efficiency of the biodegradation process.…”

Haererehalobacter sp. JS1, a bioemulsifier producing halophilic bacterium isolated from Indian solar salt works

“…It was reported that, the hydrocarbon metabolism might occur in the microbes including halophilic hydrocarbonoclastic bacteria living in hypersaline conditions . The surfactants help to increase the adhesion efficiency with polycyclic aromatic hydrocarbons (PAH) to the biodegradation by Pseudomonas putida ATCC 17514 has been proved by Rodrigues et al …”