Roumanian Biotechnological Letters Vol. 14, No. 3, 2009, pp. 4428-4435 Copyright © 2008 Bucharest University Printed in Romania. All rights reserved Roumanian Society of Biological Sciences ORIGINAL PAPER 4430 Studies on the composition of biofilms used in the reconversion of oily greases from industrial wastewaters Received for publication, September 20, 2008 Accepted, May 25, 2009 DIANA PĂSĂRIN*, STELA POPOVICI*, ANDREEA ŢUŢULAN-CUNIŢĂ**, NICOLETA CONSTANTIN** , VERONICA STOIAN** *National Research&Development Institute for Chemistry and Petrochemistry – ICECHIM, 202 Splaiul Independenţei, Sector 6, 060021, Bucharest, Romania E-mail: dianapasarin11@yahoo.com ** Genetics Department, Faculty of Biology, Bucharest University, 1-3 Aleea Portocalilor, Sector 5, 77206, Bucharest, Romania Abstract A significant part of the research focusing on biofilms deals particularly with their (negative) effects in medicine. However, biofilms can be used in a multitude of practical scopes. Due to some characteristics of this form of supracellular organization of microorganisms, such as: functioning as a self-contained system, increased resistance to stress, ability to use limited nutritional resources, biofilms were increasingly used in different biotechnologies for wastewater treatment. Among different types of industrial wastes, oily wastewater is one of the most hazardous to the environment, as the oil molecules form a film on the water surface, thus impeding oxygenation and leading to dangerous long term - even irreversible - modifications of the aquatic biotope. The importance of theoretical and practical knowledge on the composition of biofilms with lipolytic properties stems from their advantageous practical applications. In view of this fact, our work attempted the identification of the bacterial strains isolated from biofilms with lipolytic properties. Thus, three strains were investigated for nutritional demands and RFLP markers. The spectra of substrates required and/or metabolized by these strains, together with DNA patterns resulted from enzymatic digestions showed that one of the strains belonged to Pseudomonas putida species, one – to P. stutzeri, while the status of the remaining strain remained uncertain. Keywords: oily wastewaters, biofilms, bio-remediation Introduction Among the lipolytic microorganisms, those able to adhere to glass, polymer, or stainless steel supports and to form biofilms belong to various bacterial species. [5, 17] There is an increasing number of papers describing methods to obtain and use biofilms in oily wastewater treatment, especially biofilms consisting of bacteria that belong to the Pseudomonas genus, also known as pseudomonads. The criteria for biological identification of Pseudomonas genus changed with the review of the old, artificial classification, based on phenotypic properties, to the new one based on genotypic properties (phylogenetic). [2, 4] Pseudomonads are important from both economical point of view and in nature, as they are active in the aerobe decomposition and biodegradation, and play a key role in the carbon cycle. [10, 11] They are known for their capacity to form biofilms and to participate in the decomposition of hardly degradable compounds, such as aliphatic and aromatic hydrocarbons, fatty acids, insecticides and other pollutants. The analysis of biofilm composition and activity represents a promising scientific and practical preoccupation, which makes use of a plethora of microbiological, biochemical, and