REV. CHIM. (Bucharest) ♦ 64♦ No. 4 ♦ 2013 http://www.revistadechimie.ro 388 Biodegradation of Pesticides DINOCAP and DNOC by Yeast Suspensions in a Batch System MARIUS ZAHARIA 1 , DAN MAFTEI 1 , CRISTINA AMALIA DUMITRAS-HUTANU 1 , AUREL PUI 1 , ZOMI CLAUDE LAGOBO 2 , OLGA PINTILIE 1 , ROBERT GRADINARU 1,* 1 Al. I. Cuza University of Iasi, 11 Carol I, 700506, Iasi, Romania 2 Abobo-Adjamé University, Laboratory of Environmental Sciences (LES), 02 BP 801, Abidjan 02, Ivory Coast Nitroaromatic compounds constitute a major class of widely distributed environmental contaminants. Many of these pollutants, including 4,6-dinitrocresol (DNOC) or Karathane (Dinocap) have been widely used pesticides that persist in some contaminated soils, and have been found in ground-waters, causing health and environmental hazards. Dinitrophenols have multiple biological effects, being used in agriculture as insecticides, fungicides, herbicides and acaricides or in medicine and biology as metabolic inhibitors. The environmentally noxious dinitrophenols and related compounds act as uncoupling agents of oxidative phosphorylation, inhibiting ATP formation within the respiratory chain. An anaerobic consortium of different bacterial species is able to completely degrade dinitro-derivatives. However, we investigate here the bioremediation of dinitrophenol contaminated environments with the yeast Saccharomyces cerevisiae, since yeast it is cheap, easily available and largely investigated. Consequently, we have treated 10 -3 M to 10 –2 M solutions of two dinitrophenol pesticides (Dinocap and DNOC) with 5g/L yeast suspensions for 1 week in a batch system. The resulted supernatants were used to treat wheat seeds in germination experiments. They displayed different toxicity patterns according to their structure. Keywords: bioremediation; yeast; pesticide; dinitrophenols; germination test Hazardous compounds in the contamination of the food supply from agricultural waste are an increasing concern worldwide. Dinitrophenols (DNP) and their derivatives are known to be toxic to the environment, being potent uncoupling agents [1-6]. Despite their overwhelming toxicity, some dinitrophenols are still used as pesticides with an important role in the chemical protection of plants [7]. These compounds act on respiratory process by blocking the reactions of oxidative phosphorylation, which results in the inhibition of ATP formation from ADP [8-9]. Trace amounts of nitrophenols have been found in spiked tap water, reservoir water and stream water [12]. Some anaerobic microorganisms degrade and use them as nitrogen source [10], whereas many studies refer to Pseudomonas sp. and Alcaligenes sp. strains [11]. However, some technical problems remain to be solved before use bacteria as a tool for hazardous-waste management. A special case is DNP toxicity to the environment, which is manifested during production, conditioning, transportation, storing and, especially, usage of these products or by manipulating and consumption of treated products [1,13]. DNP pesticides proved also to be noxious to higher plants in germination experiments [6]. DNP likely affects the biostructural level of eukaryotic organisms [14,15]; therefore, some coupled germination experiments could be reliable tools to reveal their toxicity to the environment [16-20]. Thus, several dinitrophenolic compounds such as Karathane, DNOC, 2,4-dinitrophenol have been tested within the germination experiments comparatively to some dinitrophenyl ethers namely dinitroanisol, 2,4-dinitro-1- (octadecyloxy)benzene, 3-(2,4-dinitrophenoxy)propan-1,2- diol [6]. These results demonstrated that germinating seeds are very sensitive toward DNP toxicity. We proposed here the use of Saccharomyces cerevisiae as a DNP biodegradating and bioaccumulating material, due to its easy availability and reduced cost, as shown previously [21-23]. Yeast cells hold the property to shift quickly from respiration to fermentation, being less sensitive to low concentration of dinitrophenols. The biodegradation events of the investigated compounds were followed by UV-Vis and infrared spectroscopy, as well as germination assays using the supernatant containing degraded dinitrophenols. Experimental part Materials and methods Reagents We used in this study analytical grade reagents, while all solutions were prepared with milliQ grade water with R = 18.2 Ω. DNP were purchased from Sigma-Aldrich (USA), unless otherwise specified. Dinocap (Karathane-Krt), which is a mixture of 2,4-dinitro-6-octylphenyl crotonates and 2,6-dinitro-4-octylphenyl crotonates, octyl here being a mixture of the methylheptyl-1-ethylhexyl-and 1- propylpentyl-isomers, was purchased from a crop protection shop in Iasi. In general, we compared two dinitrophenolic pesticides, DNOC and Krt, with other dinitrophenols prepared both under classical conditions and under microwaves [24-27]. Biological materials Baker’s yeast was purchased weekly from SC Rompak srl Pascani (Romania), and kept in a humidor at 4 °C. Triticum aestivum wheat seeds, Gasparom variety, have been taken from Suceava Agricultural Research Station. Instruments. A Libbra S35 PC UV/VIS spectrophotometer (Biochrom, UK) was used for spectral measurements. For both UV and VIS-domains quartz cuvettes (Helma/Müllheim) with a 1-cm path length were used [28-30]. Mass spectrometric analysis was performed using a Shimadzu GCMS-QP2010 * email: robert.gradinaru@uaic.ro