Colloids and Surfaces B: Biointerfaces 111 (2013) 36–42 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces B: Biointerfaces jou rn al hom epage: www.elsevier.com/locate/colsurfb Modification of surface and enzymatic properties of Achromobacter denitrificans and Stenotrophomonas maltophilia in association with diesel oil biodegradation enhanced with alkyl polyglucosides Karina Sałek a , Agnieszka Zgoła-Grze ´ skowiak b , Ewa Kaczorek a,∗ a Institute of Chemical Technology and Engineering, Poznan University of Technology, M. Sklodowskiej-Curie 2, 60-965 Poznan, Poland b Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland a r t i c l e i n f o Article history: Received 13 February 2013 Received in revised form 16 April 2013 Accepted 16 May 2013 Available online xxx Keywords: Alkyl polyglucosides Biodegradation Cell surface properties Oxygenases Zeta potential a b s t r a c t The article concerns the influence of selected alkyl polyglucosides on biodegradation, cell surface and enzymatic properties of Stenotrophomonas maltophilia and Achromobacter denitrificans. The biodegradation of diesel oil depends on several factors including type and the amount of surfactant as well as bacterial genera used in the process. Nevertheless, a careful selection of these variables must be made as some bacterial strains prefer to use surfactants as their carbon source. This leads to the lowered biodegradation of diesel oil as can be observed for the tested S. maltophilia strain. Alkyl polyglucosides influenced the cell surface properties of both of the tested strains in slightly different ways. Especially for A. denitrificans, for which the hydrophobicity increased with concentration of both – Lutensol GD 70 and Glucopon 215 in diesel oil–surfactant systems. Moreover, judging by the efficiency of biodegrada- tion, the most effective process was observed in the presence of Lutensol GD 70 (240 and 360 mg L -1 ) with biodegradation rising from 32% (without surfactant) to 68%. No such relation was observed for S. maltophilia. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Continuous progress in petroleum industry results in severe environmental pollution. The application of biological methods, especially biodegradation, has gained high popularity over recent years [1]. Since the bioremediation processes are said to be one of the most efficient methods in pollution treatment [2], constant work on improving these methods seems to be crucial. Therefore, many studies were devoted to the use of commercial products in the biodegradation of petroleum hydrocarbons [3]. Such products can be understood as commercial microbial-based products [3,4] or surface active agents – such as Triton X-100 or saponins [5,6]. The most well-known surfactants used in biodegradation are non-ionic agents. However, also in other branches of industry (cos- metic, washing etc.) these substances seem to be playing a leading role now. Among these, undoubtedly the alkyl polyglucosides (APGs) are the most popular [7]. The main advantages of these surfactants are not only their ability to undergo a biodegradation process [8], but also the fact that they can be obtained from natural and renewable sources such as corn, potatoes, wheat or coconut oil [9]. The abovementioned features, as well as their ∗ Corresponding author. Tel.: +48 61 665 3688; fax: +48 61 665 3649. E-mail address: ewa.kaczorek@put.poznan.pl (E. Kaczorek). physicochemical properties make APGs suitable for use as wetting agents or emulsifiers in the industry [10]. There are many reports on the biodegradation of diesel oil using different surfactants [11], but there is hardly anything in the literature stating if and how the APGs can affect the biological degradation of petroleum hydrocarbons. The objective of the present study was the assessment of the influence of selected alkyl polyglucosides (Glucopon 215, Gluco- pon 650 and Lutensol GD 70) on the biodegradation of diesel oil and their impact on the hydrophobicity and zeta potential of cho- sen environmental bacterial strains: Stenotrophomonas maltophilia and Achromobacter denitrificans, as well as enzymatic activity in relation to biodegradation of diesel oil enhanced with tested sur- factants. Moreover, the biodegradation of alkyl polyglucosides was also estimated. 2. Materials and methods 2.1. Chemicals Hydrocarbon and other fine chemicals of high grade employed in the study were purchased from Merck (Germany). LC–MS grade methanol and ammonium acetate used in LC–MS/MS analysis were from Sigma–Aldrich (USA). Surfactants used were: Lutensol GD 70, Glucopon 215 and Glucopon 250 (Henkel, Germany). Diesel oil was 0927-7765/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.colsurfb.2013.05.021