Biodegradation of diesel fuel by a microbial consortium in the presence of 1-alkoxymethyl-2-methyl-5-hydroxypyridinium chloride homologues

Abstract

Fast development of ionic liquids as gaining more and more attention valuable chemicals will undoubtedly lead to environmental pollution. New formulations and application of ionic liquids may result in contamination in the presence of hydrophobic compounds, such as petroleum mixtures. We hypothesize that in the presence of diesel fuel low-water-soluble ionic liquids may become more toxic to hydrocarbon-degrading microorganisms. In this study the influence of 1-alkoxymethyl-2-methyl-5-hydroxypyridinium chloride homologues (side-chain length from C(3) to C(18)) on biodegradation of diesel fuel by a bacterial consortium was investigated. Whereas test performed for the consortium cultivated on disodium succinate showed that toxicity of the investigated ionic liquids decreased with increase in side-chain length, only higher homologues (C(8)-C(18)) caused a decrease in diesel fuel biodegradation. As a result of exposure to toxic compounds also modification in cell surface hydrophobicity was observed (MATH). Disulphine blue active substances method was employed to determine partitioning index of ionic liquids between water and diesel fuel phase, which varied from 1.1 to 51% for C(3) and C(18) homologues, respectively. We conclude that in the presence of hydrocarbons acting as a solvent, the increased bioavailability of hydrophobic homologues is responsible for the decrease in biodegradation efficiency of diesel fuel.

Why do microorganisms produce rhamnolipids?

“…Based on the experimental data and analysis of biodegradation kinetics during several experiments a different mechanism of substrate uptake by microorganisms was proposed: direct contact of microbial cells with the hydrophobic carbon source. Changes in microbial surface properties, hydrophobicity in particular, were connected with the mechanism of direct substrate uptake from the oil phase (Chrzanowski et al 2009a). Such changes, induced as a result of adsorption of rhamnolipids or other surfactants on the cell surface, would make for an alternative method of overcoming the limiting factors in substrate transport (Chrzanowski et al 2006b, 2009b).…”

Biosurfactants: Production and potential application in insect pest management

“…Basically, these microorganisms produce different biosurfactants for various purposes; for instance, rhamnolipids increase the solubility of hydrophobic hydrocarbons [2], cause changes in microbial surface properties [3], and enhance the bioavailability of potential hydrophobic carbon sources [4]. Unlike the chemically synthesized surfactants, biosurfactants are generally categorized based on their microbial origin and chemical composition [5].…”