Dechlorination activity detection in Streptomyces sp. M7

S.A. CUOZZO,; C.N.CHAVARRÍA,; G.C. ROLLÁN,; C.M. ABATE; AND M.J. AMOROSO

Dalian, China

Simposio; Thirteenth International Biotechnology Symposium & Exhibition; 2008

Dechlorination activity detection in Streptomyces sp M7   1Cuozzo S.A., 1Chavarría C.N., 2Rollan, G. C., 1Abate C.M. and 1Amoroso M.J. 1PROIMI-CONICET Avda Berlgrano y Pje Caseros San Miguel de Tucumán-Argentina. 2CERELA-CONICET Chacabuco 145 San Miguel de Tucumán-Argentina. scuozzo@proimi.org.ar   Abstract: The contamination with halogenated aliphatic compounds residues (as gamma-hexachlorocyclohexane) are often considered to be relatively recalcitrant because they can found in soil, water, air, plants, agricultural products, animals, food, and humans [1,2]. The lindane (gamma-hexachlorocyclohexane) is a lyphophilic compound, and therefore tends to accumulate and concentrate in the body fat of the man [3] and it is one of the major problems facing the industrialized world. Lindane is considered a potential carcinogen and it is listed as priority pollutant by the US EPA [4]. Little information is available on the ability of organochlorine pesticide biotransformation by Gram-positive microorganisms and particularly by actinomycete species, the main group of bacteria present in soils and sediments [5]. However an indigenous isolated Streptomyces sp M7 strain demonstrated that it can grow in the lindane presence as only carbon sources [6]. The ability of actinomycetes to transform organochlorine pesticides has not been widely investigated, nevertheless the metabolic pathways for pesticide biodegradation by Gram negative bacteria have been more extensively studied than in Gram-positive bacteria, as the case of an aerobic degradation way of lindane until the mineralización by Sphingobium japonicum[7], where the first step is the dehalogenase activity to obtain pentachlorocyclohexene. The aim of this work is to determine if Streptomyces sp. M7 possess   the dehalogenase activity because so far there is no any information. Dehalogenase activity was measured using free-cell extract from Streptomyces sp. M7 cultured in flasks containing 30 ml liquid minimal medium supplemented with and without lindane 10 mg/1, on a rotatory shaker (100 rpm) at 30 ºC, for 96 h. Samples were taken at 96 h and centrifuged (9,900 g, 10 min), the cells were broken by the French Press and centrifuged. The supernatant was used by detecting the dechlorination reaction. The dechlorination activity was measured by spectrophotometer at l595 nm [8]. Optimal temperature, pH and Ca concentration were determined for optimizing the dechlorinase activity. The obtained results show that Streptomyces sp. M7 presents intracellular dechlorinase activity. It is also four-times more than the control.  On the other hand the best conditions for the dechlorinase activity are 30 ºC , alkaline pH (9.5) and the presence of  calcium cation at 0.5 mM final concentration.  These results show for the first time the presence of the dechlorinase activity in an actinomycete strain. The knowledge of the best conditions for maximal activity is of great importance by the future in facing the biorremediation improvement in lindane contaminated environment.   References: [1]Chaile, A.P., Romero, N., Amoroso, M.J., del Hidalgo, M.V., Apella, M.C., 1999. Organochlorine pesticides in Sali River. Tucumán–Argentina (In Spanish). Revista Boliviana de Ecología 6, 203–209. [2]Botella, B., Crespo, J., Rivas, A., Cerrillo, I., Olea-Serrano, M.F., Olea, N., 2004. Exposure of women to organochlorine pesticides in Southern Spain. Environmental Research 96, 34–40. [3]Johri, A.K., Dua, M., Saxena, D.M., Sethunathan, N., 2000. Enhanced degradation of hexachlorocyclohexane isomers by Sphingomonas paucimobilis. Current Microbiology 41, 309–311. [4]Walker, K., Vallero, D.A. and Lewis, R.G., 1999. Factors influencing the distribution of lindane and other hexachlorocyclohexanes in the environment. Environ. Sci. Technol., 33, 4373–4378. [5]De Schrijver, A., De Mot, R., 1999. Degradation of pesticides by actinomycetes. Critical Reviews in Microbiology 25, 85–119. [6]Benimelia, C.S., Fuentesa, M.S., Abatea, C.M.,  Amoroso, M.J. 2008 Bioremediation of lindane-contaminated soil by Streptomyces sp. M7 and its effects on Zea mays growth. International Biodeterioration & Biodegradation. In press [7] Nagata Y., Endo R., Ito M., Ohtsubo Y., Tsuda M. 2007 Aerobic degradation of lindane (gamma-hexachlorocyclohexane) in bacteria and its biochemical and molecular basis. Appl. Microbiol. Biotechnol. 76, 741-52. [8]Phillips, T.M., Seech, A.G., Lee, H., Trevors, J.T.,2001. Colorimetric assay for lindane dechlorination by bacteria. Journal of Microbiological Methods 47, 181–188.